.\"
.\" TclX.n
.\"
.\" Extended command set and environment for Tcl.
.\"----------------------------------------------------------------------------
.\" Copyright 1992-1999 Karl Lehenbauer and Mark Diekhans.
.\" Copyright 2004 ActiveState Corporation.
.\"
.\" Permission to use, copy, modify, and distribute this software and its
.\" documentation for any purpose and without fee is hereby granted, provided
.\" that the above copyright notice appear in all copies.  Karl Lehenbauer and
.\" Mark Diekhans make no representations about the suitability of this
.\" software for any purpose.  It is provided "as is" without express or
.\" implied warranty.
.\"----------------------------------------------------------------------------
.\" $Id: TclX.n,v 8.23 2004/11/22 21:58:20 hobbs Exp $
.\"----------------------------------------------------------------------------
.\"
.TH "TclX" TCL "" "Tcl"
.ad b
.SH NAME
TclX \- Extended Tcl: Extended command set for Tcl
'
.SH SYNOPSIS
\fBpackage require Tclx\fR
.PP
.SH "INTRODUCTION"
.PP
This man page contains the documentation for all of the extensions that are
added to Tcl by Extended Tcl (TclX).  TclX extends Tcl's capabilities by
adding new commands to it, without changing the syntax of standard Tcl.
Extended Tcl is a superset of standard Tcl and is built alongside the
standard Tcl sources.
.PP
Extended Tcl was created by Karl Lehenbauer and Mark Diekhans and is freely
redistributable for any use without license or fee.
.PP
Available since 1989, Extended Tcl, also known as TclX, not only adds
capabilities to Tcl, but has also been the source of many of the
capabilities of the baseline Tcl release, including arrays, files, sockets,
file events, and date and time handling, among others.
.PP
Extended Tcl introduces a set of new commands and a user-extensible library
of useful Tcl procedures, any of which can be automatically loaded on the
first attempt to execute it.
.PP
The command descriptions are separated into several sections:
.RS 5
.TP
\(bu General Commands
.TP
\(bu Debugging and Development Commands
.TP
\(bu Unix Access Commands
.TP
\(bu File Commands
.TP
\(bu Network Programming Support
.TP
\(bu File Scanning Commands
.TP
\(bu Math Commands
.TP
\(bu List Manipulation Commands
.TP
\(bu Keyed Lists
.TP
\(bu String and Character Manipulation Commands
.TP
\(bu XPG/3 Message Catalog Commands
.TP
\(bu Help Facility
.TP
\(bu Tcl Loadable Libraries and Packages
.RE
'
.bp
.SH "GENERAL COMMANDS"
.PP
A set of general, useful Tcl commands, includes a command to begin
an interactive session with Tcl, a facility for tracing execution,
and a looping command.
'
'\"@help: tcl/status/dirs
'\"@brief: List the directories in the directory stack.
.TP
\fBdirs\fR
This procedure lists the directories in the directory stack.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/control/commandloop
'\"@brief: Create an interactive command loop or event based command reader.
.TP
\fBcommandloop \fR?\fB\-async\fR? ?\fB\-interactive \fBon | off | tty\fR? ?\fB\-prompt1 \fIcmd\fR? ?\fB\-prompt2 \fIcmd\fR? ?\fB\-endcommand \fIcmd\fR?
.IP
Create an interactive command loop reading commands from stdin and writing
results to stdout.  Command loops are maybe either be blocking or event
oriented.  This command is useful for Tcl scripts that do not normally
converse interactively with a user through a Tcl command interpreter, but
which sometimes want to enter this mode, perhaps for debugging or user
configuration.  The command loop terminates on EOF.
.IP
The following options are available:
.RS
.TP
\fB\-async\fR
A command handler will be associated with stdin.  When input is available
on stdin, it will be read and accumulated until a full command is available.
That command will then be evaluated.  An event loop must be entered
for input to be read and processed.
'
.TP
\fB\-interactive on | off | tty\fR
Enable or disable interactive command mode.  In interactive mode, commands
are prompted for and the results of comments are printed.  The value maybe
any boolean value or \fBtty\fR.  If \fBtty\fR is used, interactive mode
is enabled if stdin is associated with a terminal or terminal emulator.
The default is \fBtty\fR.
'
.TP
\fB\-prompt1 \fIcmd\fR
If specified, \fIcmd\fR  is used is evaluate and its result used for the
main command prompt.  If not specified, the command in \fBtcl_prompt1\fR
is evaluated to output the prompt.  Note the difference in behavior,
\fIcmd\fR results is used, while \fBtcl_prompt1\fR outputs.  This is to
allow for future expansion to command loops that write to other than
stdout.
'
.TP
\fB\-prompt2 \fIcmd\fR
If specified, \fIcmd\fR is used is evaluate and its result used for the
secondary (continuation) command prompt.  If not specified, the command in
\fBtcl_prompt2\fR is evaluated to output the prompt.
'
.TP
\fB\-endcommand \fIcmd\fR
If specified, \fIcmd\fR is evaluated when the command loop terminates.
.IP
In interactive mode, the results of set commands with two arguments are
not printed.
.IP
If \fBSIGINT\fR is configured to generate a Tcl error, it can be used to
delete the current command being type without aborting the program in
progress.
.RE
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/echo
'\"@brief: Echo one or more strings to stdout, followed by a newline.
.TP
\fBecho \fR?\fIstr ...\fR?
Writes zero or more strings to standard output, followed by a newline.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/infox
'\"@brief: Return information about Extended Tcl, or the current application.
.TP
\fBinfox\fR \fIoption\fR
.IP
Return information about Extended Tcl, or the current application.  
The following \fBinfox\fR command options are available:
.RS
.TP
\fBversion\fR
Return the version number of Extended Tcl.  The version number for
Extended Tcl is generated by combining the base version of the standard Tcl
code with another number indicating the version of Extended Tcl being used.
.TP
\fBpatchlevel\fR
Return the patchlevel for Extended Tcl.
.TP
\fBhave_fchown\fR
Return \fB1\fR if the \fBfchown\fR system call is available.  This supports
the \fB\-fileid\fR option on the \fBchown\fR and \fBchgrp\fR commands.
.TP
\fBhave_fchmod\fR
Return \fB1\fR if the \fBfchmod\fR system call is available.  This supports
the \fB\-fileid\fR option on the \fBchmod\fR command.
.TP
\fBhave_flock\fR
Return \fB1\fR if the \fBflock\fR command defined,  \fB0\fR if it is not
available.
.TP
\fBhave_fsync\fR
Return \fB1\fR if the \fBfsync\fR system call is available and the \fBsync\fR
command will sync individual files.
\fB0\fR if it is not available and the \fBsync\fR command will always sync
all file buffers.
.TP
\fBhave_ftruncate\fR
Return \fB1\fR if the \fBftruncate\fR or \fBchsize\fR system call is available.  If it is,
the \fBftruncate\fR command \fB\-fileid\fR option maybe used.
.TP
\fBhave_msgcats\fR
Return \fB1\fR if XPG message catalogs are available, \fB0\fR if they are
not.  The \fBcatgets\fR is designed to continue to function without message
catalogs, always returning the default string.
.TP
\fBhave_posix_signals\fR
Return \fB1\fR if Posix signals are available (\fBblock\fR and \fBunblock\fR
options available for the signal command).  \fB0\fR is returned if Posix
signals are not available.
.TP
\fBhave_signal_restart\fR
Return \fB1\fR if restartable signals are available (\fB-restart\fR
option available for the signal command).  \fB0\fR is returned if restartable
signals are not available.
.TP
\fBhave_truncate\fR
Return \fB1\fR if the \fBtruncate\fR system call is available.
If it is, the \fBftruncate\fR command may truncate by file path.
.TP
\fBhave_waitpid\fR
Return \fB1\fR if the \fBwaitpid\fR system call is available and the
\fBwait\fR command has full functionality.  \fB0\fR if the \fBwait\fR
command has limited functionality.
.TP
\fBappname\fR
Return the symbolic application name of the current application linked with
the Extended Tcl library.  The C variable \fBtclAppName\fR must be set by the
application to return an application specific value for this variable.
.TP
\fBapplongname\fR
Return a natural language name for the current application. The C variable
\fBtclLongAppName\fR must be set by the application to return an application
specific value for this variable.
.TP
\fBappversion\fR
Return the version number for the current application.  The C variable
\fBtclAppVersion\fR must be set by the application to return an 
application-specific value for this variable.
.TP
\fBapppatchlevel\fR
Return the patchlevel for the current application.  The C variable
\fBtclAppPatchlevel\fR must be set by the application to return an 
application-specific value for this variable.
.RE
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/variables/for_array_keys
'\"@brief: Do a foreach-style loop on each key in an array.
.TP
\fBfor_array_keys\fR \fIvar array_name code\fR
This procedure performs a foreach-style loop for each key in the named
array.  The \fBbreak\fR and \fBcontinue\fR statements work as with
\fBforeach\fR.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/for_recursive_glob
'\"@brief: A foreach-style loop for all matched (globbed) files.
.TP
\fBfor_recursive_glob\fR \fIvar dirlist globlist code\fR
This procedure performs a foreach-style loop over recursively matched files.
All directories in \fIdirlist\fR are recursively searched (breadth-first),
comparing each file found against the file glob patterns in \fBgloblist\fR.
For each matched file, the variable \fIvar\fR is set to the file path and
\fIcode\fR is evaluated.
Symbolic links are not followed.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/control/loop
'\"@brief: Higher-performance for-style loop.
.TP
\fBloop\fR \fIvar first limit ?increment? body\fR
\fBLoop\fR is a looping command, similar in behavior to the Tcl \fBfor\fR
statement, except that the \fBloop\fR statement achieves substantially higher
performance and is easier to code when the beginning and ending values of a
loop are known, and the loop variable is to be incremented by a known, fixed
amount every time through the loop.
.sp
 The \fIvar\fR argument is the name of a Tcl variable that will contain the
loop index.  The loop index is set to the value specified by
\fIfirst\fR.  The Tcl interpreter is invoked upon \fIbody\fR zero or more
times, where \fIvar\fR is incremented by \fIincrement\fR every time through
the loop, or by one if \fIincrement\fR is not specified.  \fIIncrement\fR can
be negative in which case the loop will count downwards.
.sp
When \fIvar\fR reaches \fIlimit\fR, the loop terminates without a subsequent
execution of \fIbody\fR.  For instance, if the original \fBloop\fR parameters
would cause \fBloop\fR to terminate, say \fIfirst\fR was one, \fIlimit\fR was
zero and \fIincrement\fR was not specified or was non-negative, \fIbody\fR is
not executed at all and \fBloop\fR returns.
.sp
The \fIfirst\fR, \fIlimit\fR and \fIincrement\fR are integer expressions.
They are only evaluated once at the beginning of the loop.
.sp
If a \fBcontinue\fR command is invoked within \fIbody\fR then
any remaining commands in the current execution of \fIbody\fR are skipped,
as in the \fBfor\fR command.
If a \fBbreak\fR command is invoked
within \fIbody\fR
then the \fBloop\fR command will
return immediately.
\fBLoop\fR returns an empty string.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/popd
'\"@brief: Pop a directory from a stack of directories and cd to it.
.TP
\fBpopd\fR
This procedure pops the top directory entry from the directory stack and
make it the current directory.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/pushd
'\"@brief: Push a directory to a stack of directories.
.TP
\fBpushd\fR ?\fIdir\fR?
This procedure pushes the current directory onto the directory stack and
\fBcd\fR to the specified directory.  If the directory is not specified,
then the current directory is pushed, but remains unchanged.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/recursive_glob
'\"@brief: Recursive filename matching (globbing).
.TP
\fBrecursive_glob\fR \fIdirlist globlist\fR
This procedure returns a list of recursively matches files.
All directories in \fIdirlist\fR are recursively searched (breadth-first),
comparing each file found against the file glob patterns in \fBgloblist\fR.
Symbolic links are not followed.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/showproc
'\"@brief: List the definition of the named procedure.
.TP
\fBshowproc \fR?\fIprocname ...?\fR
This procedure lists the definition of the named procedures.  Loading
them if it is not already loaded.  If no procedure names are supplied,
the definitions of all currently loaded procedures are returned.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/control/try_eval
'\"@brief: Evaluate commands with error catch and finalization.
.TP
\fBtry_eval\fR \fIcode\fR \fIcatch\fR ?\fIfinally\fR?
The \fBtry_eval\fR command evaluates \fIcode\fR in the current context.
.P
If an error occurs during the evaluation and \fIcatch\fR is not
empty, then \fIcatch\fR is evaluated to handler the error.  The result
of the command, containing the error message, will be stored in a global
variable \fBerrorResult\fR.  The global variables \fBerrorResult\fR,
\fBerrorInfo\fR and \fBerrorCode\fR will be imported into the current
scope, there is no need to execute a \fBglobal\fR command.  The result
of the \fIcatch\fR command becomes the result of the \fBtry_eval\fR command.
If the error that caused the \fIcatch\fR to be evaluate is to be continued,
the following command should be used:
.br
.nf
	\fBerror $errorResult $errorCode $errorInfo\fR
.fi
.br
.P
If the \fIfinally\fR argument is supplied and not empty, it is evaluated
after the evaluation of the \fIcode\fR and the \fIcatch\fR commands.
If an error occurs during the evaluation of the \fIfinally\fR command, it
becomes the result of the \fBtry_eval\fR command.  Otherwise, the result
of either \fIcode\fR  or \fIcatch\fR is preserved, as described above.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "DEBUGGING AND DEVELOPMENT COMMANDS"
This section contains information on commands and procedures that are
useful for developing and debugging Tcl scripts.

'\"@help: tcl/debug/cmdtrace
'\"@brief: Trace Tcl execution.
.TP
\fBcmdtrace\fR \fIlevel\fR | \fBon\fR ?\fBnoeval\fR? ?\fBnotruncate\fR? ?\fIprocs\fR? ?\fIfileid\fR? ?\fBcommand\fI cmd\fR?
.IP
Print a trace statement for all commands executed at depth of \fIlevel\fR or
below (1 is the top level).  If \fBon\fR is specified, all commands at any
level are traced.  The following options are available:
.RS
.TP
\fBnoeval\fR
Causes arguments to be printed unevaluated.  If \fBnoeval\fR
is specified, the arguments are printed before
evaluation.  Otherwise, they are printed afterwards.
.sp
If the command line is longer than 60 characters, it is truncated
to 60 and a "..." is postpended to indicate that there was more output
than was displayed.
If an evaluated 
argument contains a space, the entire argument will be enclosed inside of
braces (`{}') to allow the reader to visually separate the arguments from
each other.
.TP
\fBnotruncate\fR
Disables the truncation of commands and evaluated arguments.
.TP
\fBprocs\fR
Enables the tracing of procedure calls only.  Commands that aren't
procedure calls (i.e. calls to commands that are written in C, C++
or some object-compatible language) are not traced if the \fBprocs\fR
option is specified.  This option is particularly useful for greatly
reducing the output of \fBcmdtrace\fR while debugging.
.TP
\fBfileid\fR
This is a file id as returned by the \fBopen\fR command.  If specified, then
the trace output will be written to the file rather than stdout.  A stdio
buffer flush is done after every line is written so that the trace may be
monitored externally or provide useful information for debugging problems that
cause core dumps.
.TP
\fBcommand\fR \fIcmd\fR
.IP
Call the specified command \fIcmd\fR on when each command is executed instead 
of tracing to a file.
See the description of the functionally below.
This option may not be specified with a \fBfileid\fR.
.RE
.IP
The most common use of this command is to enable tracing to a file during the
development.  If a failure occurs, a trace is then available when needed.
Command tracing will slow down the execution of code, so it should be
removed when code is debugged.  The following command will enable tracing
to a file for the remainder of the program:
.IP
.nf
.ft CW
	cmdtrace on [open cmd.log w]
.ft R
.fi
.IP
The \fBcommand\fR option causes a user specified trace command to be called
for each command executed.
The command will have the following arguments appended to it before evaluation:
.RS
.IP "\fIcommand\fR"
A string containing the text of the command, before any
argument substitution.
.IP "\fIargv\fR"
A list of the final argument information that will be passed to
the command after command, variable, and backslash substitution.
.IP "\fIevalLevel\fR"
The \fBTcl_Eval\fR call level.
.IP "\fIprocLevel\fR"
The procedure call level.
.RE
.IP
The command should be constructed in such a manner that it will work if
additional arguments are added in the future.  It is suggested that the command
be a \fBproc\fR with the final argument being \fBargs\fR.
.IP
Tracing will be turned off while the command is being executed.  The values
of the \fBerrorInfo\fR and \fBerrorCode\fR variables will be saved and
restored on return from the command.  It is the command's responsibility
to preserve all other state.
.IP
If an error occurs during the execution of \fBcommand\fR, an error message
is dumped to \fRstderr\fR and the tracing is disabled.  The underlying
mechanism that this functionality is built on does not support returning
an error to the interpreter.
.TP
\fBcmdtrace off\fR
Turn off all tracing.
.TP
\fBcmdtrace depth\fR
Returns the current maximum trace level, or zero if trace is disabled.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/debug/edprocs
'\"@brief: Edit named procs, or all procs.
.TP
\fBedprocs \fR?\fIproc\fR...?
This procedure writes the named procedures, or all currently defined
procedures, to a temporary file, then calls an editor on it (as
specified by the \fBEDITOR\fR environment variable, or \fBvi\fR if none
is specified), then sources the file back in if it was changed.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/debug/profile
'\"@brief: Collect Tcl script performance profile data.
.TP
\fBprofile\fR ?\fI\-commands\fR? ?\fI\-eval\fR? \fBon\fR
.TP
\fBprofile off\fR \fIarrayVar\fR
This command is used to collect a performance profile of a Tcl script.  It
collects data at the Tcl procedure level. The number of calls to a procedure,
and the amount of real and CPU time is collected. Time is also collected for
the global context.  The procedure data is collected by bucketing it based on
the procedure call stack, this allows determination of how much time is spent
in a particular procedure in each of it's calling contexts.
.sp
The \fBon\fR option enables profile data collection. If the \fB\-commands\fR
option is specified, data on all commands within a procedure is collected
as well a procedures.  Multiple occurrences of a command within a procedure
are not distinguished, but this data may still be useful for analysis.
.sp
The \fBoff\fR option turns off profiling and moves the data collected to the
array \fIarrayVar\fR.  The array is address by a list containing the procedure
call stack.  Element zero is the top of the stack, the procedure that the
data is for.  The data in each entry is a list consisting of the procedure
call count and the real time and CPU time in milliseconds spent in the
procedure (but not any procedures it calls). The list is in the form
{\fIcount real cpu\fR}.
.sp
Normally, the variable scope stack is used in reporting where time is
spent.
Thus upleveled code is reported in the context that it was executed in, not
the context that the uplevel was called in.
If the \fB\-eval\fR option is specified, the procedure evaluation (call) stack
is used instead of the procedure scope stack.  Upleveled code is reported in
the context of the procedure that did the uplevel.
.sp
A Tcl procedure \fBprofrep\fR is supplied for reducing the data and
producing a report.
.sp
On \fBWindows\fR, profile command only reports elapsed real time,
CPU time is not available and is reported as zero.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/debug/profrep
'\"@brief: Generate a report from data collect from the profile command.
.TP
\fBprofrep\fR \fIprofDataVar sortKey\fR ?\fIoutFile\fR? ?\fIuserTitle\fR?
This procedure generates a report from data collect from the profile command.
\fBProfDataVar\fR is the name of the array containing the data returned by the
\fBprofile\fR command. \fBSortKey\fR indicates which data value to sort by.
It should be one of "\fBcalls\fR", "\fBcpu\fR" or "\fBreal\fR".
\fBOutFile\fR is the name of file to write the report to.  If omitted,
stdout is assumed.  \fBUserTitle\fR is an optional title line to add to
output.
.IP
Listed with indentation below each procedure or command is the procedure
call stack.
The first indented line being the procedure that invoked the reported
procedure or command.
The next line is the procedure that invoked the procedure above it, and
so on.
If no indented procedures are shown, the procedure or command was called from
the global context.
Time actually spent in the global context is listed on a line labeled
\fB<global>\fR.
Upleveled code is reported in the context that it was executed in, not
the context that the uplevel was called in.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/debug/saveprocs
'\"@brief: Save named procs to a file, or all procs.
.TP
\fBsaveprocs\fR \fIfileName\fR ?\fIproc\fR...?
This procedure saves the definition of the named procedure, or all
currently defined procedures if none is specified, to the named file.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "UNIX ACCESS COMMANDS"
.PP
These commands provide access to many basic Unix facilities, including process
handling, date and time processing, signal handling
and the executing commands via the shell.
'
'\"@help: tcl/time/alarm
'\"@brief: Set a process alarm clock.
.TP
\fBalarm\fR \fIseconds\fR
Instructs the system to send a SIGALRM signal in the specified number of
seconds.  This is a floating point number, so fractions of a section may be
specified.
If \fIseconds\fR is 0.0, any previous alarm request is canceled.
Only one alarm at a time may be active; the command returns the number of
seconds left in the previous alarm.  On systems without the \fBsetitimer\fR
system call, \fIseconds\fR is rounded up to an integer number of seconds.
.sp
The \fBalarm\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/execl
'\"@brief: Perform a process exec, executing a file.
.TP
\fBexecl \fR?\fB\-argv0\fR argv0\fR? \fIprog\fR ?\fIarglist\fR?
Do an execl, replacing the current program (either Extended Tcl or an
application with Extended Tcl embedded into it) with \fIprog\fR and
passing the arguments in the list \fIarglist\fR.
.sp
The \fB\-argv0\fR options specifies that \fIargv0\fR is to be passed to the
program as argv [0] rather than \fIprog\fR.
.sp
Note: If you are using \fBexecl\fR in a Tk application and it fails,
you may not do anything that accesses the X server or you will receive
a \fBBadWindow\fR error from the X server.  This includes executing the
Tk version of the \fBexit\fR command.  We suggest using the following
command to abort Tk applications after an \fBexecl\fR failure:
.sp
.nf
.ft CW
    kill [id process]
.ft R
.fi
.sp
On \fBWindows\fR, where the \fBfork\fR command is not available,
\fBexecl\fR starts a new process and returns the process id.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/chroot
'\"@brief: Change root directory.
.TP
\fBchroot\fR \fIdirname\fR
Change root directory to \fIdirname\fR, by invoking the POSIX \fBchroot(2)\fR
system call.  This command only succeeds if running as root.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/fork
'\"@brief: Fork the current Tcl process.
.TP
\fBfork\fR
Fork the current Tcl process.  Fork returns zero to the child process and the
process number of the child to the parent process. 
If the fork fails, a Tcl error is generated.
.sp
If an \fBexecl\fR is not
going to be performed before the child process does output, or if a
\fBclose\fR and \fBdup\fR sequence is going to be performed on \fBstdout\fR or
\fBstderr\fR, then a
\fBflush\fR should be issued against \fBstdout\fR, \fBstderr\fR and any other
open output file before doing the \fBfork\fR. Otherwise characters from the
parent process pending in the buffers will be output by both the parent
and child processes.
.sp
Note: If you are \fBfork\fRing in a Tk based application you must \fBexecl\fR
before doing any window operations in the child or you will receive a
\fBBadWindow\fR error from the X server.
.sp
The \fBfork\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/id
'\"@brief: Access, set or convert process, user and group information.
.TP
\fBid options\fR
.IP
This command provides a means of getting, setting and converting user, group
and process ids.  The \fBid\fR command has the following options:
'
.RS
.TP
\fBid user \fR?\fIname\fR?
.TP
\fBid userid \fR?\fIuid\fR?
Set the real and effective user ID to \fIname\fR or \fIuid\fR, if the
name (or uid) is valid and permissions allow it.  If the name (or uid)
is not specified, the current name (or uid) is returned.
.TP
\fBid convert userid\fR \fIuid\fR
.TP
\fBid convert user\fR \fIname\fR
Convert a user ID number to a user name, or vice versa.
.TP
\fBid group \fR?\fIname\fR?
.TP
\fBid groupid \fR?\fIgid\fR?
Set the real and effective group ID to \fIname\fR or \fIgid\fR, if the
name (or gid) is valid and permissions allow it.  If the group name
(or gid) is not specified, the current group name (or gid) is returned.
.TP
\fBid groups\fR
.TP
\fBid groupids\fR
Return the current group access list of the process.  The option
\fBgroups\fR returns group names and \fBgroupids\fR returns id numbers.
.TP
\fBid convert groupid\fR \fIgid\fR
.TP
\fBid convert group\fR \fIname\fR
Convert a group ID number to a group name, or vice versa.
.TP
\fBid effective user\fR
.TP
\fBid effective userid\fR
Return the effective user name, or effective user ID number, respectively.
.TP
\fBid effective group\fR
.TP
\fBid effective groupid\fR
Return the effective group name, or effective group ID number, respectively.
.TP
\fBid effective groupids\fR
Return all of the groupids the user is a member of.
.TP
\fBid host\fR
Return the hostname of the system the program is running on.
.TP
\fBid process\fR
Return the process ID of the current process.
.TP
\fBid process parent\fR
Return the process ID of the parent of the current process.
.TP
\fBid process group\fR
Return the process group ID of the current process.
.TP
\fBid process group set\fR
Set the process group ID of the current process to its process ID.
.TP
\fBid host\fR
Returns the standard host name of the machine the process is executing on.
.IP
On \fBWindows\fR, only the \fBhost\fR and \fBprocess\fR options
are implemented.
.RE
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/kill
'\"@brief: Send a signal to the specified process.
.TP
\fBkill\fR ?\fB\-pgroup\fR ?\fIsignal\fR? \fIidlist\fR
.IP
Send a signal to the each process in the list \fIidlist\fR, if permitted.
\fISignal\fR, if present, is the signal number or the symbolic name of the
signal, see the signal system call manual page.  The leading ``SIG''
is optional
when the signal is specified by its symbolic name.
The default for \fIsigno\fR is 15, SIGTERM.
.IP
If \fB\-pgroup\fR is specified, the numbers in \fIidlist\fR are take
as process group ids and the signal is sent to all of the process in that
process group.  A process group id of \fB0\fR specifies the current process
group.
.IP
On \fBWindows\fR, the \fBkill\fR command is capable of
terminating a process, but not of sending an arbitrary signal.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/link
'\"@brief: Create a link to a file.
.TP
\fBlink\fR ?\fB\-sym\fR? \fIsrcpath destpath\fR
.IP
Create a directory entry, \fIdestpath\fR, linking it to the existing file,
\fIsrcpath\fR.  If \fB\-sym\fR is specified, a symbolic link, rather than
a hard link, is created.  (The \fB\-sym\fR option is only available
on systems that support symbolic links.)
.IP
The \fBlink\fR command is not available on \fBWindows\fR.  Use the Tcl 8.4+
\fBfile link\fR command instead.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/nice
'\"@brief: Change or return the process priority.
.TP
\fBnice \fR?\fIpriorityincr\fR?
.IP
Change or return the process priority.
If \fIpriorityincr\fR is omitted, the current priority is returned.  If
\fIpriorityincr\fR is positive, it is added to the current \fIpriority\fR
level, up to a system defined maximum (normally \fB19\fR),
.IP
Negative \fIpriorityincr\fR values cumulatively increase the program's priority
down to a system defined minimum (normally \fB\-19\fR);
increasing priority with negative niceness values will only work for the
superuser.
.IP
The new priority is returned.
.IP
The \fBnice\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/readdir
'\"@brief: Read the contents of a directory.
.TP
\fBreaddir\fR ?\fI\-hidden\fR? \fIdirPath\fR
.IP
Returns a list containing the contents of the directory \fIdirPath\fR.  The
directory entries "." and ".." are not returned.
.IP
On \fBWindows\fR, \fB\-hidden\fR maybe specified to include hidden files
in the result.  This flag is ignored on Unix systems.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/signals/signal
'\"@brief: Specify action to take when a signal is received.
.TP
\fBsignal\fR ?\fI\-restart\fR? \fIaction\fR \fIsiglist\fR ?\fIcommand\fR?
.IP
Warning:  If signals are being used as an event source (a \fBtrap\fR
action), rather than
generating an error to terminate a task; one must use the \fB-restart\fR
option.  This causes a blocked system call, such as \fBread\fR or
\fBwaitpid\fR to be restarted rather than generate an error.  Failure
to do this may results in unexpected errors when a signal arrives
while in one of these system calls.
When available, the \fB-restart\fR option can prevent this problem.
.IP
If \fB-restart\fR is specified, restart blocking system calls rather than
generating an error.  The signal will be handled once the Tcl command 
that issued the system call completes.
The \fB-restart\fR options is not available on all operating systems and
its use will generate an error when it is not supported.  
Use \fBinfox have_signal_restart\fR to check for availability.
.IP
Specify the action to take when a Unix signal is received by Extended
Tcl, or a program that embeds it.  \fISiglist\fR is a list
of either the symbolic or numeric Unix signal (the SIG prefix is optional).
\fIAction\fR is one of the following actions to be performed on receipt of the
signal.  To specify all modifiable signals, use `*' (this will not include
SIGKILL and SIGSTOP, as they can not be modified).
.RS
.IP "\fBdefault\fR" 
Perform system default action when signal is received
(see \fBsignal\fR system call documentation).
.IP "\fBignore\fR"
Ignore the signal.
.IP "\fBerror\fR"
Generate a catchable Tcl error.  It will be as if the command
that was running returned an error.  The error code will be in the form:
.br
.nf
	\fBPOSIX SIG\fR \fIsigname\fR
.fi
.br
For the death of child signal, \fIsigname\fR will always be SIGCHLD, rather
than SIGCLD, to allow writing portable code.
.IP "\fBtrap\fR"
When the signal occurs, execute \fIcommand\fR and continue
execution if an error is not returned by \fIcommand\fR.  The command will
be executed in the global context.  The command will be edited before
execution, replacing occurrences of "%S" with the signal name.
Occurrences of "%%" result in a single "%".  This editing occurs just before
the trap command is evaluated. 
If an error is returned,
then follow the standard Tcl error mechanism.  Often \fIcommand\fR will just
do an \fBexit\fR.
.IP "\fBget\fR"
Retrieve the current settings of the specified signals.  A keyed
list will be returned were the keys are one of the specified signals and the
values are a list consisting of the action associated with the signal, a
\fB0\fR if the signal may be delivered (not block) and a \fB1\fR if it is
blocked and a flag indicating if restarting of system calls is specified.
The actions maybe one of `\fBdefault\fR',`\fBignore\fR',
`\fBerror\fR' or `\fBtrap\fR'.  If the action is trap, the third element is the
command associated with the action.  The action `\fBunknown\fR' is returned
if a non-Tcl signal handler has been associated with the signal.
.IP "\fBset\fR"
Set signals from a keyed list in the format returned by the
\fBget\fR.  For this action, \fIsiglist\fR is the keyed list of signal
state.  Signals with an action of `\fBunknown\fR' are not modified.
.IP "\fBblock\fR"
Block the specified signals from being received. (Posix systems
only).
.IP "\fBunblock\fR"
Allow the specified signal to be received. Pending signals
will not occur. (Posix systems only).
.RE
.IP
The signal action will remain enabled after the specified signal has occurred.
The exception to this is \fBSIGCHLD\fR on systems without Posix signals.
For these systems, \fBSIGCHLD\fR is not be automatically reenabled.  After a
\fBSIGCHLD\fR signal is received, a call to \fBwait\fR must be
performed to retrieve the exit status of the child process before issuing
another \fBsignal SIGCHLD \fI...\fR command.  For code that is to be portable
between both types of systems, use this approach.
.IP
Signals are not processed until after the completion of the Tcl command that
is executing when the signal is received.  If an interactive Tcl shell is
running, then the \fBSIGINT\fR will be set to \fBerror\fR, non-interactive
Tcl sessions leave \fBSIGINT\fR unchanged from when the process started
(normally \fBdefault\fR for foreground processes and \fBignore\fR for
processes in the background).
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/time/sleep
'\"@brief: Sleep for the specified number of seconds.
.TP
\fBsleep\fR \fIseconds\fR
.br
Sleep the Extended Tcl process for \fIseconds\fR seconds.
\fISeconds\FR, if specified as a decimal number, 
is truncated to an integer value. 
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/system
'\"@brief: Execute command via `system' call.
.TP
\fBsystem\fR \fIcmdstr1\fR ?\fIcmdstr2\fR...?
.br
Concatenates  \fIcmdstr1\fR,  \fIcmdstr2\fR etc with space separators
(see the \fBconcat\fR command) into a single command and then evaluates
the command using the standard system shell.  On Unix systems, this is
\fB/bin/sh\fR and on Windows its \fBcommand.com\fR.  The exit code of
the command is returned.
.sp
This command differs from the \fBexec\fR command
in that \fBsystem\fR doesn't return the executed command's standard output
as the
result string, and
\fBsystem\fR goes through the Unix shell to provide wild card
expansion, redirection, etc,
as is normal from an \fBsh\fR command line.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/sync
'\"@brief: Force a file or all files to be written to disk.
.TP
\fBsync \fR?\fIfileId\fR?
.IP
If \fIfileId\fR is not specified, or if it is and this system does
not support the \fIfsync\fR system call, issues a \fIsync\fR system
call to flush all pending disk output.  If \fIfileId\fR is specified
and the system does support the \fIfsync\fR system call, issues an
\fIfsync\fR on the file corresponding to the specified Tcl \fIfileId\fR
to force all pending output to that file out to the disk.
.IP
If \fIfileId\fR is specified, the file must be writable.  A \fBflush\fR
will be issued against the \fIfileId\fR before the sync.
.IP
The \fIinfox have_fsync\fR command can be used to determine if
"\fBsync\fR \fIfileId\fR" will do a \fIsync\fR or a \fIfsync\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/time/times
'\"@brief: Get process and child execution times.
.TP
\fBtimes\fR
.br
Return a list containing the process and child execution times in the form:
.br
.nf
	\fIutime stime cutime cstime\fR
.fi
.br
Also see the \fItimes\fR(2) system call manual page.
The values are in milliseconds.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/status/umask
'\"@brief: Get or set the file-creation mode mask.
.TP
\fBumask \fR?\fIoctalmask\fR?
.br
Sets file-creation mode mask to the octal value of \fIoctalmask\fR.
If \fIoctalmask\fR is omitted, the current mask is returned.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/processes/wait
'\"@brief: Wait for a child process to terminate.
.TP
\fBwait \fR?\fB\-nohang\fR? ?\fB\-untraced\fR? ?\fB\-pgroup\fR? ?\fIpid\fR?
.br
Waits for a process created with the \fBexecl\fR command to terminate, either
due to an untrapped signal or call to \fIexit\fR system call.
If the process id \fIpid\fR is specified, they wait on that process, otherwise
wait on any child process to terminate.
.sp
If \fB\-nohang\fR is specified, then don't block waiting on a process to
terminate.  If no process is immediately available, return an empty list.
If \fB\-untraced\fR is specified then the status of child processes
that are stopped, and whose status has not yet been reported since they
stopped, are also returned.
If \fB\-pgroup\fR is specified and \fIpid\fR is not specified, then wait
on any child process whose process group ID is they same as the
calling process. If \fIpid\fR is specified with \fB\-pgroup\fR, then
it is take as a process group ID, waiting on any process in that process group
to terminate.
.sp
\fBWait\fR returns a list containing three elements: The first element is the
process id of the process that terminated.
If the process exited normally, the second element is `EXIT', and the third
contains the numeric exit code.
If the process terminated due to a signal, the second element is `SIG', and
the third contains the signal name.
If the process is currently stopped (on systems that support SIGSTP), the
second element is `STOP', followed by the signal name.
.sp
Note that it is possible to wait on processes to terminate that were create
in the background with the \fBexec\fR command.  However, if any other
\fBexec\fR command is executed after the process terminates, then the
process status will be reaped by the \fBexec\fR command and will not be
available to the \fBwait\fR command.  
.sp
On systems without the \fBwaitpid\fR system call, the \fB\-nohang\fR,
\fB\-untraced\fR and \fB\-pgroup\fR options are not available.
The \fBinfox have_waitpid\fR command maybe use to determine if this
functionality is available.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "FILE COMMANDS"
.PP
These commands provide extended file access and manipulation.
This includes searching ASCII-sorted data files, copying files,
duplicating file descriptors, control of file access options, retrieving open
file status, and creating pipes with the \fBpipe\fR system call.  Also linking
files, setting file, process, and user attributes and truncating files.
An interface to the \fBselect\fR system call is available on Unix systems that
support
it.
.PP
It should be noted that Tcl file I/O is implemented on top of the stdio 
library.  By default, the file is buffered.  When communicating to a process
through a pipe, a \fBflush\fR command should be issued to force the data
out.  Alternatively, the \fBfcntl\fR command may be used to set the buffering
mode of a file to line-buffered or unbuffered.
'
'\"@help: tcl/files/bsearch
.TP
\fBbsearch\fR \fIfileId key\fR ?\fIretvar\fR? ?\fIcompare_proc\fR?
.br
Search an opened file \fIfileId\fR containing lines of text sorted into
ascending order for a match.
\fIKey\fR contains the string to match.
If \fIretvar\fR is specified, then the line from the
file is returned in \fIretvar\fR, and the command returns \fB1\fR if \fIkey\fR
was found, and \fB0\fR if it wasn't.  If \fIretvar\fR is not specified
or is a null name, then the command returns the line that was found, or an
empty string if \fIkey\fR wasn't found.
.sp
By default, the key is matched against the first white-space separated field
in each line.  The field is treated as an ASCII string.  If \fIcompare_proc\fR
is specified, then it
defines the name of a Tcl procedure to evaluate against each
line read from the sorted file during the execution of the
\fBbsearch\fR command.  \fICompare_proc\fR takes two arguments, the key
and a line extracted from the file.  The compare routine should return a
number less than zero if the key is less than the line, zero if the key
matches the line, or greater than zero if the key is greater than the line.
The file must be sorted in ascending order according to the same criteria
\fIcompare_proc\fR uses to compare the key with the line, or erroneous
results will occur.
.sp
This command does not work on files containing binary data (bytes of zero).
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/chmod
'\"@brief: Set file permissions.
.TP
\fBchmod \fR[\fB\-fileid\fR] \fImode\fR \fIfilelist\fR
.br
Set permissions of each of the files in the list \fIfilelist\fR to \fImode\fR,
where \fImode\fR is an absolute numeric mode or symbolic permissions as in the
UNIX \fBchmod(1)\fR command.  To specify a mode as octal, it should be
prefixed with a "0" (e.g. 0622).
.sp
If the option \fB\-fileid\fR is specified, \fIfilelist\fR is a list of open
file identifiers rather than a list of file names.  This option is not
available on all Unix systems.  Use the \fBinfox have_fchmod\fR command
to determine if this functionality is available.
.sp
The \fBchmod\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/chown
'\"@brief: Change file owner and/or group.
.TP
\fBchown \fR[\fB\-fileid\fR] \fIowner\fR | {\fIowner group\fR} \fIfilelist\fR
.br
Set owner of each file in the list \fIfilelist\fR to \fIowner\fR, which can
be a user
name or numeric user id.  If the first parameter is a list, then the
owner is set to the first element of the list and the group is set to the
second element.  \fIGroup\fR can be a group name or numeric group id.
If \fIgroup\fR is {}, then the file group will be set to the login
group of the specified user.
.sp
If the option \fB\-fileid\fR is specified, \fIfilelist\fR is a list of open
file identifiers rather than a list of file names.  This option is not
available on all Unix systems.  Use the \fBinfox have_fchown\fR command
to determine if this functionality is available.
.sp
The \fBchown\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/chgrp
'\"@brief: Change file group.
.TP
\fBchgrp \fR[\fB\-fileid\fR] \fIgroup\fR \fIfilelist\fR
.br
Set the
group id of each file in the list \fIfilelist\fR to \fIgroup\fR, which can
be either a
group name or a numeric group id.
.sp
If the option \fB\-fileid\fR is specified, \fIfilelist\fR is a list of open
file identifiers rather than a list of file names.  This option is not
available on all Unix systems.  Use the \fBinfox have_fchown\fR command
to determine if this functionality is available.
.sp
The \fBchgrp\fR command is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/dup
'\"@brief: Duplicate an open file
.TP
\fBdup\fR \fIfileId\fR ?\fItargetFileId\fR?
.br
Duplicate an open file.  A new file id is opened that addresses the
same file as \fIfileId\fR.
.sp
If \fItargetFileId\fR is specified, the the file is dup to this specified file
id.  Normally this is \fBstdin\fR, \fBstdout\fR, or \fBstderr\fR.
The dup command will handle flushing output and closing this file.
The new file will be buffered, if its needs to be unbuffered, use the
\fBfcntl\fR command to set it unbuffered.
.sp
If \fIfileId\fR is a number rather than a Tcl file id, then the \fBdup\fR
command will bind that file to a Tcl file id.  This is useful for accessing
files that are passed from the parent process.
The argument ?\fItargetFileId\fR? is not valid with this operation.
.sp
On \fBWindows\fR, only \fBstdin\fR, \fBstdout\fR, or \fBstderr\fR or a
non-socket file handle number maybe specified for \fItargetFileId\fR.  The
\fBdup\fR command does not work on sockets on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/fcntl
'\"@brief: Get or set file access options for an open file.
.TP
\fBfcntl\fR \fIfileId\fR \fIattribute ?value\fR?
.br
This command either sets or clears a file option or returns its current
value.  If \fIvalue\fR is not specified, then the current value of
\fBattribute\fR is returned.  All values are boolean. Some attributes maybe
only be gotten, not modified.
The following attributes may be specified:
.IP \fBRDONLY\fR 
The file is opened for reading only. (Get only)
.IP \fBWRONLY\fR
The file is opened for writing only.  (Get only)
.IP \fBRDWR\fR
The file is opened for reading and writing.  (Get only)
.IP "\fBREAD\fR   "
If the file is readable. (Get only).
.IP \fBWRITE\fR
If the file is writable. (Get only).
.IP \fBAPPEND\fR 
The file is opened for append-only writes.  All writes will
be forced to the end of the file. (Get or set).
.IP \fBNONBLOCK\fR
The file is to be accessed with non-blocking I/O.  See the
\fBread\fR system call for a description of how it affects the behavior of
file reads.
.IP \fBCLOEXEC\fR 
Close the file on an process exec.  If the \fBexecl\fR
command or some other mechanism causes the process to do an
exec, the file will be closed if this option is set.
.IP \fBNOBUF\fR 
The file is not buffered. If set, then there no buffering
for the file.
.IP \fBLINEBUF\fR 
Output the file will be line buffered. The buffer will
be flushed when a newline is written, when the buffer is full,
or when input is requested.
.IP \fBKEEPALIVE\fR 
Keep a socket connection alive.
If SIGPIPE is enabled, then it is sent if connection is broken and data is
written to the socket.
If SIGPIPE is ignored, an error is returned on the write.  This attribute is
valid only on sockets.
By default, SIGPIPE is ignored in Tcl.
.IP
The \fBNONBLOCK\fR, \fBNOBUF\fR and \fBLINEBUF\fR are provided for
compatibility with older scripts.
The\fBfconfigure\fR command is preferred method of getting and setting these
attributes.
.IP
The \fBAPPEND\fR and \fBCLOEXEC\fR options are not available on
\fBWindows\fR.
.RE
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/flock
'\"@brief: Lock all or part of a file.
.TP
\fBflock\fR \fIoptions fileId\fR ?\fIstart\fR? ?\fIlength\fR? ?\fIorigin\fR?
.IP
This command places a lock on all or part of the file specified by
\fIfileId\fR.  The lock is either advisory or mandatory, depending on the mode
bits of the file.  The lock is placed beginning at relative byte offset
\fIstart\fR for \fIlength\fR bytes.  If \fIstart\fR or \fIlength\fR is omitted
or empty, zero is assumed.  If \fIlength\fR is zero, then the lock always
extents to end of file, even if the file grows.  If \fIorigin\fR is
"\fBstart\fR", then the offset is relative to the beginning of the file. If it
is "\fBcurrent\fR", it is relative to the current access position in the file.
If it is "\fBend\fR", then it is relative to the end-of-file (a negative is
before the EOF, positive is after).  If \fIorigin\fR is omitted, \fBstart\fR
is assumed.
.IP
The following \fIoptions\fR are recognized:
.RS
.IP \fB\-read\fR 
Place a read lock on the file.  Multiple processes may be
accessing the file with read-locks.
.IP \fB\-write\fR 
Place a write lock on the file.  Only one process may be
accessing a file if there is a write lock.
.IP \fB\-nowait\fR 
If specified, then the process will not block if the lock
can not be obtained.  With this option, the command returns 1 if the lock
is obtained and 0 if it is not.
.RE
.IP
See your system's \fBfcntl\fR system call documentation for full details of
the behavior of file locking.  If locking is being done on ranges of a
file, it is best to use unbuffered file access (see the \fBfcntl\fR command).
.IP
The \fBflock\fR command is not available on \fBWindows 95\fR.
It is available on \fBWindows NT\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/for_file
'\"@brief: Do a foreach-style loop on each line in a file.
.TP
\fBfor_file\fR \fIvar filename code\fR
.br
This procedure implements a loop over the contents of a file.
For each line in \fIfilename\fR, it sets
\fIvar\fR to the line and executes \fIcode\fR.
.sp
The \fBbreak\fR and \fBcontinue\fR commands work as with foreach.
.sp
For example, the command
.sp
.nf
.ft CW
	for_file line /etc/passwd {echo $line}
.ft R
.fi
.sp
would echo all the lines in the password file.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/funlock
'\"@brief: Remove a lock from part or all of a file.
.TP
\fBfunlock\fR \fIfileId\fR ?\fIstart\fR? ?\fIlength\fR? ?\fIorigin\fR?
.br
Remove a locked from a file that was previously placed with the \fIflock\fR
command.  The arguments are the same as for the \fIflock\fR command, see
that command for more details.
.sp
The \fBfunlock\fR command is not available on \fBWindows 95\fR.
It is available on \fBWindows NT\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/fstat
'\"@brief: Obtain status information about an open file.
.TP
\fBfstat\fR \fIfileId\fR ?\fIitem\fR? | ?\fBstat \fIarrayvar\fR?
.IP
Obtain status information about an open file.
.IP
The following keys are used to identify data items:
.RS
.IP "\fBatime\fR"
The time of last access.
.IP "\fBctime\fR"
The time of last file status change
.IP "\fBdev\fR"
The device containing a directory for the file.  This value
uniquely identifies the file system that contains the file.
.IP "\fBgid\fR"
The group ID of the file's group.
.IP "\fBino\fR"
The inode number.  This field uniquely identifies the file in a
given file system.
.IP "\fBmode\fR"
The mode of the file (see the \fBmknod\fR system call).
.IP "\fBmtime\fR" 
Time when the data in the file was last modified.
.IP "\fBnlink\fR"
The number of links to the file.
.IP "\fBsize\fR"
The file size in bytes.
.IP "\fBtty\fR"
If the file is associated with a terminal, then 1 otherwise 0.
.IP "\fBtype\fR"
The type of the file in symbolic form, which is one of the
following values: \fBfile\fR, \fBdirectory\fR, \fBcharacterSpecial\fR,
\fBblockSpecial\fR, \fBfifo\fR, \fBlink\fR, or \fBsocket\fR.
.IP "\fBuid\fR"
The user ID of the file's owner.
.RE
.IP
If one of these keys is specified as \fIitem\fR, then that data item is
returned.
.IP
If \fBstat \fIarrayvar\fR is specified, then the information is returned in
the array \fIarrayvar\fR.  Each of the above keys indexes an element of the
array containing the data.
.IP
If only \fIfileId\fR is specified, the command returns the data as a keyed
list.
.IP
The following values may be returned only if explicitly asked for, it will not
be returned with the array or keyed list forms:
.RS
.IP "\fBremotehost\fR"
If \fIfileId\fR is a TCP/IP socket connection, then a
list is returned with the first element being the remote host IP address.  If
the remote host name can be found, it is returned as the second element of
the list.  The remote host IP port number is the third element.
.IP "\fBlocalhost\fR"
If \fIfileId\fR is a TCP/IP socket connection, then a
list is returned with the first element being the local host IP address.  If
the local host name can be found, it is returned as the second element of
the list.  The local host IP port number is the third element.
.RE
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/ftruncate
'\"@brief: Truncate a file to a specified size.
.TP
\fBftruncate \fR[\fB\-fileid\fR] \fIfile newsize\fR
.br
Truncate a file to have a length of at most \fInewsize\fR bytes.
.sp
If the option \fB\-fileid\fR is specified, \fIfile\fR is an open
file identifier, otherwise it is a file path.
.sp
This command is not available or not fully functional if the underlying
operating system support is not available.  The command \fBinfox have_truncate\fR
will indicate if this command may truncate by file path.  The command
\fBinfox have_ftruncate\fR will indicate if this command may truncate by file id.
.sp
The \fB\-fileid\fR option is not available on \fBWindows\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/lgets
'\"@brief: Read a list for a file, handles embedded newlines.
.TP
\fBlgets\fR \fIfileId\fR ?\fIvarName\fR?
.br
Reads the next Tcl list from the file given by \fIfileId\fR and discards
the terminating newline character.  This command differs from the \fBgets\fR
command, in that it reads Tcl lists rather than lines.  If the list
contains newlines or binary data, then that newline or bytes of zero will be
returned as part of the result.
Only a newline not quoted as part of the list indicates the end of the list.
There is no corresponding command for outputting lists, as \fBputs\fR will
do this correctly.
.sp
If \fIvarName\fR is specified, then the line is placed in the variable
by that name and the return value is a count of the number of characters
read (not including the newline).
If the end of the file is reached before reading
any characters then \-1 is returned and \fIvarName\fR is set to an
empty string.
If \fIvarName\fR is specified and an error occurs, what ever data was
read will be returned in the variable, however the resulting string
may not be a valid list.
.sp
If \fIvarName\fR is not specified then the return value will be
the line (minus the newline character) or an empty string if
the end of the file is reached before reading any characters.
An empty string will also be returned if a line contains no characters
except the newline, so \fBeof\fR may have to be used to determine
what really happened.
.sp
The \fBlgets\fR command maybe used to read and write lists containing
binary data, however translation must be set to \fBlf\fR or the
data maybe corrupted.
.sp
If \fBlgets\fR is currently supported on non-blocking files.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'
'\"@help: tcl/files/pipe
'\"@brief: Create a pipe.
.TP
\fBpipe\fR ?\fIfileId_var_r fileId_var_w\fR?
.br
Create a pipe.  If \fIfileId_var_r\fR
and \fIfileId_var_r\fR are specified, then \fBpipe\fR will set the a
variable named \fIfileId_var_r\fR to
contain the fileId of the side of the pipe that was opened for reading,
and \fIfileId_var_w\fR will contain the fileId of the side of the
pipe that was opened for writing.
.sp
If the fileId variables are not specified, then a
list containing the read and write fileIdw is returned as the
result of the command.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/read_file
'\"@brief: Read in a file to a string.
.TP
\fBread_file\fR ?\fB\-nonewline\fR? \fIfileName\fR
.TP
\fBread_file\fR \fIfileName\fR \fInumBytes\fR
.br
This procedure reads the file \fIfileName\fR and returns the contents as
a string.  If \fB\-nonewline\fR is specified, then the last character of
the file is discarded if it is a newline.  The second form specifies
exactly how many bytes will be read and returned, unless there are fewer
than \fInumBytes\fR bytes left in the file; in this case, all the
remaining bytes are returned.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/select
'\"@brief: Synchronous I/O multiplexing.
.TP
\fBselect\fR \fIreadfileIds\fR ?\fIwritefileIds\fR? ?\fIexceptfileIds\fR? ?\fItimeout\fR?
.br
This command allows an Extended Tcl program to wait
on zero or more files being ready for
for reading, writing, have an exceptional condition pending, or for
a timeout period to expire.
\fIreadFileIds\fR, \fIwriteFileIds\fR, \fIexceptFileIds\fR are each lists
of fileIds, as returned from \fBopen\fR, to query.  An empty list ({}) may
be specified if a category is not used. 
.sp
The files specified by
the \fIreadFileIds\fR list are checked to see if data is available for
reading. The \fIwriteFileIds\fR are checked if the specified
files are clear for writing.
The
\fIexceptFileIds\fR are checked to see if an exceptional condition has
occurred (typically, an error).
The write and exception checking is most useful on devices, however,
the read checking is very useful when communicating with multiple
processes through pipes.  Select considers data pending in the stdio
input buffer for read files as being ready for reading, the files do.
not have to be unbuffered.
.sp
\fITimeout\fR is a floating point timeout value, in seconds.  If an empty
list is supplied (or the parameter is omitted), then no timeout is set.  If
the value is zero, then the \fBselect\fR command functions as a poll of the
files, returning immediately even if none are ready.
.sp
If the \fItimeout\fR period expires with none of the files becoming ready,
then the command returns an empty list.  Otherwise the command returns a 
list of three elements, each of those elements is a list of the fileIds
that are ready in the read, write and exception classes.  If none are ready in
a class, then that element will be the null list.  For example:
.sp
.nf
.ft CW
        select {file3 file4 file5} {file6 file7} {} 10.5
.ft R

could return

.ft CW
        {file3 file4} {file6} {}
.ft R

or perhaps

.ft CW
        file3 {} {}
.ft R
.fi
.sp
On \fBWindows\fR, only sockets can be used with the \fBselect\fR
command.
Pipes, as returned by the \fBopen\fR command, are not supported.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/files/write_file
'\"@brief: Write strings out to a file.
.TP
\fBwrite_file\fR \fIfileName string ?string...?\fR
.br
This procedure writes the specified strings to the named file.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "NETWORK PROGRAMMING SUPPORT"
.PP
TclX provides functionality to complement the Tcl \fBsocket\fR command.
The \fBhost_info\fR command is used to get information about a host by
name or IP address.  In addition, the \fBfstat\fR and \fBfcntl\fR commands
provide options of querying and controlling connected sockets.
To obtain the host name of the system the local system, use the
\fBid host\fR command.
'
'\"@help: tcl/sockets/host_info
'\"@brief: Obtain information about an Internet host.
.TP
\fBhost_info \fIoption\fR \fIhost\fR
.br
Obtain information about an Internet host. The argument \fIhost\fR can be
either a host name or an IP address.
.IP
The following subcommands are recognized:
.RS
.IP \fBaddresses\fR
Return the list of IP addresses for \fIhost\fR.
.IP \fBofficial_name\fR
Return official name for \fIhost\fR.
.IP \fBaliases\fR
Return the list of aliases for \fIhost\fR.
(Note that these are IP number aliases, not DNS \fICNAME\fR
aliases. See \fIifconfig(2)\fR.)
.RE
'\"@endhelp
'
.bp
.SH "FILE SCANNING COMMANDS"
.PP
These commands provide a facility to scan files, matching lines of the file
against regular expressions and executing Tcl code on a match.  With this
facility you can use Tcl to do the sort of file processing
that is traditionally done with \fIawk\fR.  And since Tcl's approach is more
declarative, some of the scripts that can be rather
difficult to write in awk are simple to code in Tcl.
.PP
File scanning in Tcl centers around the concept of a \fIscan context\fR.
A scan context contains one or more match statements, which associate
regular expressions to scan for with Tcl code to be executed when the
expressions are matched.
'
'\"@help: tcl/filescan/scancontext
'\"@brief: Manage file scan contexts.
.TP
\fBscancontext\fR ?\fIoption\fR?
.br
This command manages file scan contexts.  A scan context is a collection of
regular expressions and commands to execute when that regular expression
matches a line of the file.  A context may also have a single default match,
to be applied against lines that do not match any of the regular expressions.
Multiple scan contexts may be defined and they may be reused on multiple files.
A scan context is identified by a context handle.  The \fBscancontext\fR
command takes
the following forms:
.TP
\fBscancontext create\fR
Create a new scan context.  The \fBscanmatch\fR command is used to define
patterns in the context.  A contexthandle is returned, which the Tcl
programmer uses to refer to the newly created scan context in calls
to the Tcl file scanning commands.
'
.TP
\fBscancontext delete\fR \fIcontexthandle\fR
.br
Delete the scan context identified by \fIcontexthandle\fR, and free all
of the
match statements and compiled regular expressions associated with the
specified context.
.TP
\fBscancontext copyfile\fR \fIcontexthandle\fR ?\fIfilehandle\fR?
.br
Set or return the file handle that unmatched lines are copied to.
(See \fBscanfile\fR).  If \fIfilehandle\fR is omitted, the copy file handle
is returned.  If no copy file is associated with the context, {} is returned.
If a file handle is specified, it becomes the copy file for
this context.  If \fIfilehandle\fR is {}, then it removes any copy file
specification for the context.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/filescan/scanfile
'\"@brief: Scan a file, executing match code when their patterns are matched.
.TP
\fBscanfile\fR ?\fI\-copyfile copyFileId\fR? \fIcontexthandle\fR \fIfileId\fR
.br
Scan the file specified by \fIfileId\fR, starting from the
current file position.  Check all patterns in the scan context specified by
\fIcontexthandle\fR against
it, executing the match commands corresponding to patterns matched.
.sp
If the optional \fI\-copyfile\fR argument is specified, the next argument
is a file ID to which all lines not matched by any pattern (excluding
the default pattern) are to be written.  If the copy file is specified with
this flag, instead of using the \fBscancontext copyfile\fR command, the 
file is disassociated from the scan context at the end of the scan.
.sp
This command does not work on files containing binary data (bytes of zero).
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'\"@help: tcl/filescan/scanmatch
'\"@brief: Specify tcl code to execute when scanfile pattern is matched.
.TP
\fBscanmatch\fR ?\fI\-nocase\fR? \fIcontexthandle\fR ?\fIregexp\fR? \fIcommands\fR
.IP
Specify Tcl \fIcommands\fR, to be evaluated when \fIregexp\fR is matched by a
\fBscanfile\fR command.  The match is added to the scan context specified by
\fIcontexthandle\fR.  Any number of match statements may be
specified for a give context.  \fIRegexp\fR is a regular expression (see the
\fBregexp\fR command).  If \fB\-nocase\fR is specified as the first argument,
the pattern is matched regardless of
alphabetic case.
.IP
If \fIregexp\fR is not specified, then a default match is
specified for the scan context.  The default match will be executed when a
line of the file does not match any of the regular expressions
in the current scancontext.
.IP
The array \fBmatchInfo\fR is available to the Tcl code that is executed
when an expression matches (or defaults).  It contains information about
the file being scanned and where within it the expression was matched.
.IP
\fBmatchInfo\fR is local to the top
level of the match command unless declared global at that level
by the Tcl \fBglobal\fR command.  If it is to
be used as a global, it \fImust\fR be declared global before \fBscanfile\fR is
called (since \fBscanfile\fR sets the \fBmatchInfo\fR before the match code is
executed, a subsequent \fBglobal\fR will override the local variable).
The following array entries are available:
.RS
.TP
\fBmatchInfo(line)\fR
Contains the text of the line of the file that was matched.
.TP
\fBmatchInfo(offset)\fR
The byte offset into the file of the first character of
the line that was matched.
.\".TP
.\"\fBmatchInfo(bytesread)\fR
.\"The number of translated bytes that have been read since the start of the
.\"scan, including the number of bytes in the current line.
.\"If end-of-line translation is enabled or automatic, the terminating characters
.\"only count as one byte, even if \fBcrlf\fR two character terminators are used.
.\"This has the advantage of giving a value that can be passed to the \fBread\fR
.\"command to get a specific block of data.
.TP
\fBmatchInfo(linenum)\fR
The line number of the line that was matched. This is relative to the first
line scanned, which is usually, but not necessarily, the first line of the
file.  The first line is line number one.
.TP
\fBmatchInfo(context)\fR
The context handle of the context that this scan is associated with.
.TP
\fBmatchInfo(handle)\fR
The file id (handle) of the file currently being scanned.
.TP
\fBmatchInfo(copyHandle)\fR
The file id (handle) of the file specified by the \fB\-copyfile\fR option.
The element does not exist if \fB\-copyfile\fR was not specified.
.TP
\fBmatchInfo(submatch0)\fR
Will contain the characters matching the first parenthesized subexpression.
The second will be contained in \fBsubmatch1\fR, etc.
.TP
\fBmatchInfo(subindex0)\fR
Will contain the a list of the starting and ending indices of the string
matching the first parenthesized subexpression.
The second will be contained in \fBsubindex1\fR, etc.
.RE
.IP
All \fBscanmatch\fR patterns that match a line will be processed in the order
in which their
specifications were added to the scan context.  The remainder of the
\fBscanmatch\fR pattern-command pairs may be skipped for a file line if a
\fBcontinue\fR is executed by the Tcl code of a preceding, matched
pattern.
.IP
If a \fBreturn\fR is
executed in the body of the match command, the \fBscanfile\fR command
currently in
progress returns, with the value passed to \fBreturn\fR as its
return value.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "MATH COMMANDS"
.PP
Several extended math commands commands make many additional math
functions available in TclX.  In addition, a set of procedures provide
command access to the math functions supported by the \fBexpr\fR command.

'\"@help: tcl/math/fmathcmds
'\"@brief: Command interfaces to the expr math functions (sin, cos, tan, etc).
.PP
The following procedures provide command interfaces to the expr math
functions. They take the same arguments as the \fBexpr\fR functions and
may take expressions as arguments.
.sp
.RS
.nf
.ta 3c 6c 9c
\fBabs\fR	\fBacos\fR	\fBasin\fR	\fBatan2\fR	
\fBatan\fR	\fBceil\fR	\fBcos\fR	\fBcosh\fR	
\fBdouble\fR	\fBexp\fR	\fBfloor\fR	\fBfmod\fR	
\fBhypot\fR	\fBint\fR	\fBlog10\fR	\fBlog\fR	
\fBpow\fR	\fBround\fR	\fBsin\fR	\fBsinh\fR	
\fBsqrt\fR	\fBtan\fR	\fBtanh\fR	
.fi
.RE
'\"@:
'\"@:These procedures are provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/math/max
'\"@brief: Return the argument that has the highest numeric value.
.TP
\fBmax\fR \fInum1\fR ?..\fInumN\fR?
.TP
\fBexpr max(num1, num2)\fR
.br
Returns the argument that has the highest numeric value. Each
argument may be any integer or floating point value.
.sp
This functionality is also available as a math function \fBmax\fR in the
Tcl \fBexpr\fR command.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/math/min
'\"@brief: Return the argument that has the lowest numeric value.
.TP
\fBmin\fR \fInum1\fR ?..\fInumN\fR?
.TP
\fBexpr min(num1, num2)\fR
.br
Returns the argument that has the lowest numeric value.  Each
argument may be any integer or floating point value.
.sp
This functionality is also available as a math function \fBmin\fR in the
Tcl \fBexpr\fR command.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/math/random
'\"@brief: Return a pseudorandom integer or set the seed.
.TP
\fBrandom\fR \fIlimit\fR | \fBseed\fR ?\fIseedval\fR?
.br
Generate a pseudorandom integer number greater than or equal to zero and
less than \fIlimit\fR.  If \fBseed\fR is specified, then the command
resets the random number generator to a starting point derived from 
the \fBseedval\fR. This allows one to reproduce 
pseudorandom number sequences
for testing purposes.
If \fIseedval\fR is omitted, then the seed is set to a value based on current
system state and the current time, providing a reasonably interesting and
ever-changing seed.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "LIST MANIPULATION COMMANDS"
.PP
Extended Tcl provides additional list manipulation commands and procedures.
'
'\"@help: tcl/lists/intersect
'\"@brief: Return a list containing every element present in both lists.
.TP
\fBintersect\fR \fIlista listb\fR
.br
Procedure to return the logical intersection of two lists.
The returned list will be sorted.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/intersect3
'\"@brief: Return three lists from an intersection of two lists.
.TP
\fBintersect3\fR \fIlista listb\fR
.br
Procedure to intersects two lists, returning a list containing
three lists:  The first list returned is everything in \fIlista\fR
that wasn't in \fIlistb\fR.  The second list contains the intersection
of the two lists, and the third list contains all the elements that
were in \fIlistb\fR but weren't in \fIlista\fR.  The returned lists will be
sorted.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lassign
'\"@brief: Assign successive elements of a list to specified variables.
.TP
\fBlassign\fR \fIlist var\fR ?\fIvar\fR...?
.br
Assign successive elements of a list to specified variables.
If there are more variable
names than fields, the remaining variables are set to the
empty string.  If there are more elements than variables, a list of the
unassigned elements is returned.
.sp
For example,
.sp
.nf
.ft CW
    lassign {dave 100 200 {Dave Foo}} name uid gid longName
.ft R
.fi
.sp
Assigns \fIname\fR to ``dave'', \fIuid\fR to ``100'', \fIgid\fR to ``200'',
and \fIlongName\fR to ``Dave Foo''.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lcontain
'\"@brief: Determine if a list contains an element.
.TP
\fBlcontain\fR \fIlist element\fR
.br
Determine if the \fIelement\fR is a list element of \fIlist\fR.
If the element is contained in the list, 1 is returned, otherwise, 0 is
returned.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lempty
'\"@brief: Determine if a list is empty. 
.TP
\fBlempty\fR \fIlist\fR
.br
Determine if the specified list is empty.
If empty, 1 is returned, otherwise, 0 is returned.  This command is an
alternative to comparing a list to an empty string, however it checks 
for a string of all whitespaces, which is an empty list.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lmatch
'\"@brief: Return a list of elements from a list that match a pattern
.TP
\fBlmatch \fR?\fImode\fR? \fIlist pattern\fR
.IP
Search the elements of \fIlist\fR, returning a list of all elements
matching \fIpattern\fR.  If none match, an empty list is returned.
.IP
The \fImode\fR argument indicates how the elements of the list are to
be matched against \fIpattern\fR and it must have one of the following
values:
.RS
.IP \fB\-exact\fR
The list element must contain exactly the same string as \fIpattern\fR.
.IP \fB\-glob\fR
\fIPattern\fR is a glob-style pattern which is matched against each list
element using the same rules as the \fBstring match\fR command.
.IP \fB\-regexp\fR
\fIPattern\fR is treated as a regular expression and matched against
each list element using the same rules as the \fBregexp\fR command.
.RE
.IP
If \fImode\fR is omitted then it defaults to \fB\-glob\fR.
.sp
Only the \fB-exact\fR comparison will work on binary data.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lrmdups
'\"@brief: Given a list, remove all of the duplicated elements.
.TP
\fBlrmdups\fR \fIlist\fR
.br
Procedure to remove duplicate elements from a list.  The returned list
will be sorted.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lvarcat
'\"@brief: Concatenate the contents lists or strings into a variable
.TP
\fBlvarcat\fI var string ?\fR\fIstring...\fR?
.br
This command treats each \fIstring\fR argument as a list and concatenates them
to the end of the contents of \fIvar\fR, forming a a single list.  The list is
stored back into \fIvar\fR and also returned as the result.  if \fIvar\fR does
not exist, it is created.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lvarpop
'\"@brief: Pop or replace the specified element from a list.
.TP
\fBlvarpop\fR \fIvar\fR ?\fIindexExpr\fR? ?\fIstring\fR?
.br
The \fBlvarpop\fR command pops (deletes) the element indexed by the expression
\fIindexExpr\fR from the list contained in the variable \fIvar\fR.
If \fIindex\fR is omitted, then 0 is assumed.
If \fIstring\fR, is specified, then the deleted element is replaced by 
\fIstring\fR. The replaced or deleted element is returned.
Thus ``lvarpop argv 0'' returns the first element of argv, setting
argv to contain the remainder of the string.
.sp
If the expression \fIindexExpr\fR starts with the string \fBend\fR, then
\fBend\fR is replaced with the index of the last element in the list.  If
the expression starts with \fBlen\fR, then \fBlen\fR is replaced with the
length of the list.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/lvarpush
'\"@brief: Push or insert the an element into a list.
.TP
\fBlvarpush\fR \fIvar string\fR ?\fIindexExpr\fR?
.br
The \fBlvarpush\fR command pushes (inserts) \fIstring\fR as an element in the
list contained in the variable \fIvar\fR.  The element is inserted before
position \fIindexExpr\fR in the list. If \fIindex\fR is omitted, then 0 is
assumed.  If \fIvar\fR does not exists, it is created.
.sp
If the expression \fIindexExpr\fR starts with the string \fBend\fR, then
\fBend\fR is replaced with the index of the last element in the list.  If
the expression starts with \fBlen\fR, then \fBlen\fR is replaced with the
length of the list.  Note the a value of \fBend\fR means insert the string
before the last element.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/lists/union
'\"@brief: Return the logical union of two lists.
.TP
\fBunion\fR \fIlista listb\fR
Procedure to return the logical union of the two specified lists.
Any duplicate elements are removed.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/intro/keyedlists
'\"@brief: Introduction to keyed lists
.bp
.SH "KEYED LISTS"
.PP
Extended Tcl defines a special type of list referred to as \fIkeyed lists\fR.
These lists provided a structured data type built upon standard Tcl lists.
This provides a functionality similar to \fIstruct\fRs in the C 
programming language.
.sp
A keyed list is a list in which each element contains a key and value pair.
These element pairs are stored as lists themselves, where the key is the first
element of the list, and the value is the second.  The key-value pairs are
referred to as \fIfields\fR.
This is an example of a keyed list:
.IP
    {{NAME {Frank Zappa}} {JOB {musician and composer}}}
'
.PP
If the variable \fBperson\fR contained the above list, then
\fBkeylget person NAME\fR would return \fB{Frank Zappa}\fR.
Executing the command:
.sp
.nf
.ft CW
	keylset person ID 106
.ft R
.fi
.PP
would make \fBperson\fR contain 
.IP
    {{ID 106} {NAME {Frank Zappa}} {JOB {musician and composer}}
.PP
Fields may contain subfields; `.' is the separator character.  Subfields
are actually fields where the value is another keyed list.  Thus 
the following list has the top level fields \fIID\fR and \fINAME\fR, and
subfields \fINAME.FIRST\fR and  \fINAME.LAST\fR:
.IP
    {ID 106} {NAME {{FIRST Frank} {LAST Zappa}}}
.PP
There is no limit to the recursive depth of subfields, allowing one
to build complex data structures.
.PP
Keyed lists are constructed and accessed via a number of commands.
All keyed list management commands take the name of the variable containing
the keyed list
as an argument (i.e. passed by reference), rather than passing the
list directly.
'\"@:
'\"@:This functionality is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/keyedlists/keyldel
'\"@brief: Delete a field of a keyed list.
.TP
\fBkeyldel\fR \fIlistvar\fR \fIkey\fR
.br
Delete the field specified by \fIkey\fR from the keyed list in the
variable \fIlistvar\fR.  This removes both the key and the value from
the keyed list.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/keyedlists/keylget
'\"@brief: Get the value of a field of a keyed list.
.TP
\fBkeylget\fR \fIlistvar\fR ?\fIkey\fR? ?\fIretvar\fR | {}?
.br
Return the value associated with \fIkey\fR from the keyed list in the
variable \fIlistvar\fR.  If \fIretvar\fR is not specified, then the value will
be returned as the result of the command.  
In this case, if \fIkey\fR is not found in the
list, an error will result.
.sp
If \fIretvar\fR is specified and \fIkey\fR is in
the list, then the value is returned in the variable \fIretvar\fR and the
command returns \fB1\fR if the key was present within the list.
If \fIkey\fR isn't in the list, the command will return \fB0\fR,
and \fIretvar\fR will be left unchanged.  If \fB{}\fR is specified for
\fIretvar\fR, the value is not returned, allowing the Tcl programmer
to determine if a key is present in a keyed list without setting a
variable as a side-effect.
.sp
If \fIkey\fR is omitted, then a list of all the keys in
the keyed list is returned.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/keyedlists/keylkeys
'\"@brief: Get the keys in a keyed list.
.TP
\fBkeylkeys\fR \fIlistvar\fR ?\fIkey\fR?
.br
Return the a list of the keys in the keyed list in the
variable \fIlistvar\fR.  If \fIkeys\fR is specified, then it is the
name of a key field  who's subfield keys are to be retrieve.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/keyedlists/keylset
'\"@brief: Set the value of a field of a keyed list.
.TP
\fBkeylset\fR \fIlistvar\fR \fIkey\fR \fIvalue\fR ?\fIkey2\fR \fIvalue2\fR ...?
.br
Set the value associated with \fIkey\fR, in the keyed list contained in the
variable \fIlistvar\fR, to \fIvalue\fR.
If \fRlistvar\fR does not exists, it is created.  If \fIkey\fR
is not currently in the list, it will be added.  If it already exists, 
\fIvalue\fR replaces the existing value.  Multiple keywords and values may
be specified, if desired.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "STRING AND CHARACTER MANIPULATION COMMANDS"
.PP
The commands provide additional functionality to classify characters, convert
characters between character and numeric values, index into a string,
determine the length of a string, extract a range of character from a string,
replicate a string a number of times, and transliterate a string (similar to
the Unix \fItr\fR program).
'
'\"@help: tcl/strings/ccollate
'\"@brief: String comparison command (include localized collation).
.TP
\fBccollate\fR ?\fI\-local\fR? \fIstring1 string2\fR
.br
This command compares two strings.  
If returns \fB\-1\fR if \fIstring1\fR is less than \fIstring2\fR, \fB0\fR if
they are equal and \fB1\fR if \fIstring1\fR is greater than \fIstring2\fR.
.sp
If \fB\-local\fR is specified, the strings are compared according to the
collation environment of the current locale.
.sp
This command does not work with binary or UTF data.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/cconcat
'\"@brief: Concatenate strings.
.TP
\fBcconcat\fR ?\fIstring1\fR? ?\fIstring2\fR? ?...?\fR
.br
Concatenate the arguments, returning the resulting string.
While string concatenation is normally performed by the parser, it is
occasionally useful to have a command that returns a string.
The is generally useful when a command to evaluate is required.
No separators are inserted between the strings.
.sp
This command is UTF-aware.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/cequal
'\"@brief: String equality convenience command.
.TP
\fBcequal\fR \fIstring string\fR
.br
This command compares two strings for equality.
It returns \fB1\fR if \fIstring1\fR and \fIstring2\fR are the identical
and \fB0\fR if they are not.
This command is a short-cut for \fBstring compare\fR and avoids the
problems with string expressions being treated unintentionally as numbers.
.sp
This command is UTF-aware and will also work on binary data.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/cindex
'\"@brief: Return indexed character from string.
.TP
\fBcindex\fR \fIstring indexExpr\fR
.br
Returns the character indexed by the expression \fIindexExpr\fR (zero based)
from \fIstring\fR.
.sp
If the expression \fIindexExpr\fR starts with the string \fBend\fR, then
\fBend\fR is replaced with the index of the last character in the string.  If
the expression starts with \fBlen\fR, then \fBlen\fR is replaced with the
length of the string.
.sp
This command is UTF-aware.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'\"@help: tcl/strings/clength
'\"@brief: Return length of specified string.
.TP
\fBclength\fR \fIstring\fR
.br
Returns the length of \fIstring\fR in characters.  
This command is a shortcut for:
.br
.nf
.ft CW
    string length string
.ft R
.fi
.sp
This command is UTF-aware.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/crange
'\"@brief: Return range of characters from string.
.TP
\fBcrange\fR \fIstring firstExpr lastExpr\fR
.br
Returns a range of characters from \fIstring\fR starting at the character
indexed by the expression \fIfirstExpr\fR (zero-based) until the character
indexed by the expression \fIlastExpr\fR.
.sp
If the expression \fIfirstExpr\fR or \fBlastExpr\fR starts with the string
\fBend\fR, then \fBend\fR is replaced with the index of the last character in
the string.  If the expression starts with \fBlen\fR, then \fBlen\fR is
replaced with the length of the string.
.sp
This command is UTF-aware.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/csubstr
'\"@brief: Return a substring from within a string.
.TP
\fBcsubstr\fR \fIstring firstExpr lengthExpr\fR
.br
Returns a range of characters from \fIstring\fR starting at the character
indexed by the expression \fIfirstExpr\fR (zero-based) for \fIlengthExpr\fR
characters.  
.sp
If the expression \fIfirstExpr\fR or \fBlengthExpr\fR starts with the string
\fBend\fR, then \fBend\fR is replaced with the index of the last character in
the string.  If the expression starts with \fBlen\fR, then \fBlen\fR is
replaced with the length of the string.
.sp
This command is UTF-aware.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/ctoken
'\"@brief: Parse a token from a character string.
.TP
\fBctoken\fR \fIstrvar separators\fR
.br
Parse a token out of a character string.
The string to parse is contained in the variable named \fIstrvar\fR.
The string \fIseparators\fR contains all of the valid separator characters
for tokens in the string.
All leading separators are skipped and the first token is returned.
The variable \fIstrvar\fR will be modified to contain the remainder of
the string following the token.
.sp
This command does not work with binary data.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/ctype
'\"@brief: Determine if a string has various characteristics.
.TP
\fBctype\fR \fI?\-failindex var? class string\fR
.br
\fBctype\fR
determines whether all characters in \fIstring\fR are of the specified
\fIclass\fR.  It returns \fB1\fR if they are all of \fIclass\fR,
and \fB0\fR if
they are not, or if the string is empty.  This command also provides another
method (besides \fBformat\fR and \fBscan\fR) of converting between an ASCII
character and its numeric value.  The following \fBctype\fR commands are
available:
.RS
.TP
\fBctype\fR \fI?\-failindex var? alnum \fIstring\fR
Tests that all characters are alphabetic or numeric characters as defined by
the character set.
.TP
\fBctype\fR \fI?\-failindex var? alpha \fIstring\fR
Tests that all characters are alphabetic characters as defined by the
character set.
.TP
\fBctype\fR \fI?\-failindex var? ascii \fIstring\fR
Tests that all characters are an ASCII character (a non-negative number less
than 0200).
.TP
\fBctype char\fR \fInumber\fR
Converts the numeric value, \fIstring\fR, to an ASCII character.  Number must
be in the range 0 through the maximum Unicode values.
.TP
\fBctype\fR \fI?\-failindex var? cntrl \fIstring\fR
Tests that all characters are ``control characters'' as defined by the
character set.
.TP
\fBctype\fR \fI?\-failindex var? digit \fIstring\fR
Tests that all characters are valid decimal digits, i.e. 0 through 9.
.TP
\fBctype\fR \fI?\-failindex var? graph \fIstring\fR
Tests that all characters within are any character for which \fIctype print\fR
is true, except for space characters.
.TP
\fBctype\fR \fI?\-failindex var? lower \fIstring\fR
Tests that all characters are lowercase letters as defined by the character
set.
.TP
\fBctype ord\fR \fIcharacter\fR
Convert a character into its decimal numeric value.  The first character of
the string is converted to its numeric Unicode value.
.TP
\fBctype\fR \fI?\-failindex var? space \fIstring\fR
Tests that all characters are either a space, horizontal-tab, carriage
return, newline, vertical-tab, or form-feed.
.TP
\fBctype\fR \fI?\-failindex var? print \fIstring\fR
Tests that all characters are a space or any character for which \fIctype
alnum\fR or \fIctype punct\fR is true or other ``printing character'' as
defined by the character set.
.TP
\fBctype\fR \fI?\-failindex var? punct \fIstring\fR
Tests that all characters are made up of any of the characters
other than the ones for which
\fBalnum\fR, \fBcntrl\fR, or \fBspace\fR is true.
.TP
\fBctype\fR \fI?\-failindex var? upper \fIstring\fR
Tests that all characters are uppercase letters as defined by the character
set.
.TP
\fBctype\fR \fI?\-failindex var? xdigit \fIstring\fR
Tests that all characters are valid hexadecimal digits, that is \fI0\fR
through \fI9\fR, a through \fIf\fR or \fIA\fR through \fIF\fR.
.RE
.IP
If \fI\-failindex\fR is specified, then the index into \fIstring\fR of the
first character that did not match the class is returned in \fIvar\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/replicate
'\"@brief: Replicate string a number of times.
.TP
\fBreplicate\fR \fIstring countExpr\fR
.br
Returns \fIstring\fR, replicated the number of times indicated by the
expression \fIcountExpr\fR.
.sp
This command is UTF-aware and will work with binary data.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/strings/translit
'\"@brief: Translate characters in a string according to patterns.
.TP
\fBtranslit\fR \fIinrange outrange string\fR
.br
Translate characters in \fIstring\fR, changing characters
occurring
in \fIinrange\fR
to the corresponding character in \fIoutrange\fR. \fIInrange\fR and 
\fIoutrange\fR may be list of characters or a range in the form `A\-M'.
For example:
.nf
.ft CW
        translit a\-z A\-Z foobar
.ft R
.if
returns "FOOBAR".
.sp
This command currently only supports characters in ASCII range; UTF-8 characters
out of this range will generate an error.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "XPG/3 MESSAGE CATALOG COMMANDS"
.PP
These commands provide a Tcl interface to message catalogs that are compliant
with the X/Open Portability Guide, Version 3 (XPG/3).
.sp
Tcl programmers can use message catalogs to create applications that
are language-independent.  Through the use of message catalogs, prompts,
messages, menus and so forth can exist for any number of languages,
and they can altered, and new languages added,  without affecting any Tcl or C
source code, greatly easing the maintenance difficulties incurred by
supporting multiple languages.
.sp
A default text message is passed to the command that fetches entries
from message catalogs.
This allows the Tcl programmer to create message catalogs containing
messages in various languages, but still have a set of default messages
available
regardless of the presence of any message catalogs, and allow the programs
to press on without difficulty when no catalogs are present.
.sp
Thus, the normal
approach to using message catalogs is to ignore errors on \fBcatopen\fR, in
which case
\fBcatgets\fR will return the default message that was specified in the call.
.sp
The Tcl message catalog commands normally ignore most errors.  If it is
desirable to detect errors,
a special option is provided.  This is normally used only 
during debugging, to
insure that message catalogs are being used.  If your Unix implementation does
not have XPG/3 message catalog support, stubs will be compiled in that will
create a version of \fBcatgets\fR that always returns the default string.
This allows for easy
porting of software to environments that don't have support for
message catalogs.
.sp
Message catalogs are global to the process, an application with multiple
Tcl interpreters within the same process may pass and share message catalog
handles.
'
'\"@help: tcl/intl/catopen
'\"@brief: Open a message catalog.
.TP
\fBcatopen\fR ?\fB\-fail\fR | \fB\-nofail\fR? \fIcatname\fR
.br
Open the message catalog \fIcatname\fR.  This may be a relative path name,
in which case the \fBNLSPATH\fR environment variable is searched to find an
absolute path to the message catalog.  A handle in the form \fBmsgcat\fIN\fR
is returned.  Normally, errors are ignored, and in the case of a failed
call to \fBcatopen\fR, a handle is returned to an
unopened message catalog.  (This handle may still be passed to \fBcatgets\fR
and \fBcatclose\fR, causing \fBcatgets\fR to simply return the default string,
as described above.  If the \fB\-fail\fR 
option is specified, an error is returned
if the open fails.  The option \fB\-nofail\fR specifies the default behavior
of not returning an error when \fBcatopen\fR fails to open a specified
message catalog.  If the handle from a failed \fBcatopen\fR is passed to
\fBcatgets\fR, the default string is returned.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/intl/catgets
'\"@brief: Retrieve a message from a message catalog.
.TP
\fBcatgets\fR \fIcatHandle setnum msgnum defaultstr\fR
.br
Retrieve a message form a message catalog. \fICatHandle\fR should be a
Tcl message catalog handle that
was returned by \fBcatopen\fR.  \fISetnum\fR is the message set number,
and \fImsgnum\fR is the message number. If the message catalog was not opened,
or the message set or message number cannot be found, then the default
string, \fIdefaultstr\fR, is returned.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/intl/catclose
'\"@brief: Close a message catalog.
.TP
\fBcatclose\fR ?\fB\-fail\fR | \fB\-nofail\fR? \fIcathandle\fR
.br
Close the message catalog specified by \fIcathandle\fR.
Normally, errors are ignored.  If \fB\-fail\fR is
specified, any errors closing the message catalog
file are returned.  The option \fB\-nofail\fR
specifies the default behavior of not returning an error.  The use of
\fB\-fail\fR only makes sense if it was also
specified in the call to \fBcatopen\fR.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.bp
'\"@help: tcl/events/mainloop
'\"@brief: Setup a top-level event loop.
.TP
\fBmainloop\fR
.br
This procedure sets up a top-level event loop.
Events are processed until there are no more active event sources, at which
time the process exits.
It is used to build event oriented programs using the TclX shell in a style
similar to that used with \fBwish\fR.
If the global variable \fBtcl_interactive\fR exists and has a true value
an interactive command handler is started as well.   If the command handler
is terminated by an EOF, the process will be exited.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "HELP FACILITY"
'\"@help: help
'\"@brief: Tcl help facility.
.PP
The help facility allows one to look up help pages which where extracted
from the standard Tcl manual pages and Tcl scripts during Tcl
installation.  Help files are structured as a multilevel tree of
subjects and help pages.  Help files are found by searching directories
named \fBhelp\fR in the directories listed in the \fBauto_path\fR
variable.  All of the files in the list of help directories form a
virtual root of the help tree.  This method allows multiple applications
to provide help trees without having the files reside in the same
directory. 
.PP
The help facility can be accessed in two ways, as interactive commands in the
Extended Tcl shell or as an interactive Tk-based program (if you have built
Extended Tcl with Tk).
.PP
To run the Tk-based interactive help program:
.sp
.nf
.ft CW
    tclhelp ?addpaths?
.ft R
.fi
.sp
Where \fIaddpaths\fR are additional paths to search for help directories.
By default, only the \fIauto_path\fR used by \fBtclhelp\fR is search.
This will result in help on Tcl, Extended Tcl and Tk.
.PP
The following interactive Tcl commands and options are provided
with the help package:
.TP
\fBhelp\fR
.br
Help, without arguments, lists of all the help subjects and pages under
the current help subject.
.TP
\fBhelp\fR \fIsubject\fR
Displays all of help pages and lower level subjects (if any exist) under
the subject \fIsubject\fR.
.TP
\fBhelp\fR \fIsubject/helppage\fR
Display the specified help page.  The help output is passed through a simple
pager if output exceeds 23 lines, pausing waiting for a return to be entered.
If any other character is entered, the output is terminated.
.TP
\fBhelpcd\fR ?\fIsubject\fR?
Change the current subject, which is much like the Unix current
directory.  If
\fIsubject\fR is not specified, return to the top-level of the help tree.
Help subject path names may also include ``..'' elements.
.TP
\fBhelppwd\fR
Displays the current help subject.
.TP
\fBhelp\fR \fIhelp\fR | ?
Displays help on the help facility at any directory level.
.TP
\fBapropos\fR \fIpattern\fR
This command locates subjects by searching their one-line descriptions for a
pattern.  \fRApropos\fR is useful when you can remember part of the name or
description of a command, and want to search through the one-line summaries
for matching lines.  Full regular expressions may be specified (see 
the \fBregexp\fR command).
'\"@:
'\"@:These procedures are provided by Extended Tcl.
'\"@endhelp
'
'\"@help: tcl/libraries/packagelib
'\"@brief: Tcl loadable libraries and packages.
.bp
.SH "TCL LOADABLE LIBRARIES AND PACKAGES"
.PP
Extended Tcl supports standard Tcl \fBtclIndex\fR libraries and package
libraries. A package library file can contain multiple independent Tcl
packages.  A package is a named collection of related Tcl procedures and
initialization code.
.PP
The package library file is just a regular Unix text file, editable with
your favorite text editor, containing packages of Tcl source code. The
package library file name must have the suffix \fB.tlib\fR.  An index
file with the same prefix name and the suffix \fB.tndx\fR
resides the same directory as the \fB.tlib\fR file.
The \fB.tndx\fR will be automatically created whenever it is out
of date or missing (provided there is write access to the directory).
.PP
The variable \fBauto_path\fR contains a list of directories that are
searched for libraries.  The first time an unknown command trap is take,
the indexes for the libraries are loaded into memory. If the
\fBauto_path\fR variable is changed during execution of a program, it
will be re-searched. Only the first package of a given name found during
the execution of a program is loaded.  This can be overridden with
\fBloadlibindex\fR command.
.PP
The start of a package is delimited by:
.IP
\fB#@package\fR: \fIpackage_name proc1\fR ?\fI..procN\fR?
.PP
These lines must start in column one.  Everything between the
\fB#@package:\fR keyword and the next \fB#@package:\fR keyword or a
\fB#@packend\fR keyword, or the end of the file, becomes part of the
named package.
The specified procedures, \fIproc1..procN\fR, are the entry points of
the package.  When a command named in a package specification is
executed and detected as an unknown command, all code in the specified
package will be sourced.
This package should define all of the procedures named on the package
line, define any support procedures required by the package and do any
package-specific initialization.  Packages declarations maybe continued
on subsequent lines using standard Tcl backslash line continuations.
The \fB#@packend\fR keyword is useful to make sure only the minimum
required section of code is sourced.  Thus for example a large comment
block at the beginning of the next file won't be loaded.
.PP
Care should be taken in defining \fIpackage_name\fR, as the first package
found in the path by with a given name is loaded.  This can be useful in
developing new version of packages installed on the system.
.PP
For example, in a package source file, the presence of the following line:
.IP
\fB#@package: directory_stack pushd popd dirs\fR
.PP
says that the text lines following that line in the package file up
to the next \fIpackage\fR line or the end of the file is a package named
\fBdirectory_stack\fR and that an attempt to execute either \fIpushd\fR,
\fIpopd\fR or \fIdirs\fR when the routine is not already defined will cause 
the \fBdirectory_stack\fR portion of the package file to be loaded.
'\"@:
'\"@:This functionality is provided by Extended Tcl.
'\"@endhelp
'
.bp
.SH "PACKAGE LIBRARY MANAGEMENT COMMANDS"
.PP
Several commands are available for building and managing package
libraries.  Commands that are extended versions of the standard
Tcl library commands are listed here.  All of the standard Tcl library
management commands and variables are also supported.
'
.TP
'\"@help: tcl/libraries/auto_commands
'\"@brief: List names of loadable library commands and procedures.
\fBauto_commands\fR ?\fB\-loaders\fR?
Lists the names of all known loadable procedures and commands
procedures.  If \fB\-loaders\fR is specified, the command that will be
executed to load the command will also be returned.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.TP
'\"@help: tcl/libraries/buildpackageindex
'\"@brief: Build index files for package libraries.
\fBbuildpackageindex\fR \fIlibfilelist\fR
.br
Build index files for package libraries.
The argument \fIlibfilelist\fR is a list of package libraries.
Each name must end with the suffix \fB.tlib\fR.
A corresponding \fB.tndx\fR file will be built.
The user must have write access to the directory containing each library.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.TP
'\"@help: tcl/libraries/convert_lib
'\"@brief: Convert an Ousterhout style tclIndex file to a package library.
\fBconvert_lib\fR \fItclIndex packagelib ?ignore?\fR
.br
Convert a Ousterhout style \fItclIndex\fR index file and associate source
files into a package library \fBpackagelib\fR.  If \fBpackagelib\fR does not
have a \fB.tlib\fR extension, one will be added.  Any files specified in 
\fItclIndex\fR that are in the list \fIignore\fR will be skipped.  Files
listed in \fIignore\fR should just be the base file names, not full paths.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.TP
'\"@help: tcl/libraries/loadlibindex
'\"@brief: Load the index of a package library
\fBloadlibindex\fR \fIlibfile.tlib\fR
.br
Load the package library index of the library file \fBlibfile\fR (which
must have the suffix \fI.tlib\fR).  Package library indexes along the
\fBauto_path\fR are loaded automatically on the first \fBdemand_load\fR;
this command is provided to explicitly load libraries that are not in
the path.  If the index file (with a \fI.tndx\fR suffix) does not exists
or is out of date, it will be rebuilt if the user has directory
permissions to create it. If a package with the same name as a package
in \fIlibfile.tlib\fR has already been loaded, its definition will be
overridden by the new package.  However, if any procedure has actually
been used from the previously defined package, the procedures from
\fIlibfile.tlib\fR will not be loaded.
'\"@:
'\"@:This command is provided by Extended Tcl.
'\"@endhelp
'
.TP
'\"@help: tcl/libraries/auto_packages
'\"@brief: List all packages.
\fBauto_packages\fR ?\fI\-location\fR?
.br
Returns a list of the names of all defined packages. If \fI\-location\fR
is specified, a list of pairs of package name and the \fB.tlib\fR path
name, offset and length of the package within the library.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
.TP
'\"@help: tcl/libraries/auto_load_file
'\"@brief: Search the auto_path for a file to source.
\fBauto_load_file\fR \fIfile\fR
.br
Source a file, as with the \fBsource\fR command, except search
\fBauto_path\fR for the file.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp
'
.TP
'\"@help: tcl/libraries/searchpath
'\"@brief: Search a path list for a file.
\fBsearchpath\fR \fIpath file\fR
.br
Search all directories in the specified path, which is a Tcl list, for the
specified file.  Returns the full path name of the file, or an empty string
if the requested file could not be found.
'\"@:
'\"@:This procedure is provided by Extended Tcl.
'\"@endhelp


