protocol

# `osp`

Portable operating-system access protocol.

Author: Paulo Moura
Version: 1.23
Date: 2018/3/7
Compilation flags:
`static`

(no dependencies on other entities)

## Public interface

### `pid/1`

Returns the process identifier of the running process.

Compilation flags:
`static`
Template:
`pid(PID)`
Mode and number of proofs:
`pid(-integer)` - `one`

### `shell/2`

Runs an operating-system shell command and returns its exit status.

Compilation flags:
`static`
Template:
`shell(Command,Status)`
Mode and number of proofs:
`shell(+atom,-integer)` - `one`

### `shell/1`

Runs an operating-system shell command.

Compilation flags:
`static`
Template:
`shell(Command)`
Mode and number of proofs:
`shell(+atom)` - `zero_or_one`

### `absolute_file_name/2`

Expands a file name to an absolute file path. An environment variable at the beginning of the file name is also expanded.

Compilation flags:
`static`
Template:
`absolute_file_name(File,Path)`
Mode and number of proofs:
`absolute_file_name(+atom,-atom)` - `one`

### `decompose_file_name/3`

Decomposes a file name into its directory (which always ends with a slash; “./” is returned if absent) and its basename (that can be the empty atom).

Compilation flags:
`static`
Template:
`decompose_file_name(File,Directory,Basename)`
Mode and number of proofs:
`decompose_file_name(+atom,?atom,?atom)` - `one`

### `decompose_file_name/4`

Decomposes a file name into its directory (which always ends with a slash; “./” is returned if absent), name (that can be the empty atom), and extension (which starts with a “.” when defined; the empty atom otherwise).

Compilation flags:
`static`
Template:
`decompose_file_name(File,Directory,Name,Extension)`
Mode and number of proofs:
`decompose_file_name(+atom,?atom,?atom,?atom)` - `one`

### `make_directory/1`

Makes a new directory. Succeeds if the directory already exists.

Compilation flags:
`static`
Template:
`make_directory(Directory)`
Mode and number of proofs:
`make_directory(+atom)` - `one`

### `make_directory_path/1`

Makes a new directory creating all the intermediate directories if necessary. Succeeds if the directory already exists.

Compilation flags:
`static`
Template:
`make_directory_path(Directory)`
Mode and number of proofs:
`make_directory_path(+atom)` - `one`

### `delete_directory/1`

Deletes an empty directory.

Compilation flags:
`static`
Template:
`delete_directory(Directory)`
Mode and number of proofs:
`delete_directory(+atom)` - `one`

### `change_directory/1`

Changes current working directory.

Compilation flags:
`static`
Template:
`change_directory(Directory)`
Mode and number of proofs:
`change_directory(+atom)` - `one`

### `working_directory/1`

Current working directory.

Compilation flags:
`static`
Template:
`working_directory(Directory)`
Mode and number of proofs:
`working_directory(?atom)` - `zero_or_one`

### `directory_files/2`

Returns a list of all files (including directories, regular files, and hidden directories and files) in a directory. File paths are relative to the directory.

Compilation flags:
`static`
Template:
`directory_files(Directory,Files)`
Mode and number of proofs:
`directory_files(+atom,-list(atom))` - `one`

### `directory_files/3`

Returns a filtered list of files. Filters: paths/1 - relative/absolute, type/1 - all/regular/directory, extensions/1 - list, prefixes/1 - list, suffixes/1 - list, dot_files/1 - boolean. Invalid options ignored. Defaults equivalent to directory_files/2.

Compilation flags:
`static`
Template:
`directory_files(Directory,Files,Options)`
Mode and number of proofs:
`directory_files(+atom,-list(atom),+list(compound))` - `one`

### `directory_exists/1`

True if the specified directory exists (irrespective of directory permissions).

Compilation flags:
`static`
Template:
`directory_exists(Directory)`
Mode and number of proofs:
`directory_exists(+atom)` - `zero_or_one`

### `file_exists/1`

True if the specified file exists and is a regular file (irrespective of file permissions).

Compilation flags:
`static`
Template:
`file_exists(File)`
Mode and number of proofs:
`file_exists(+atom)` - `zero_or_one`

### `file_modification_time/2`

File modification time (which can be used for comparison).

Compilation flags:
`static`
Template:
`file_modification_time(File,Time)`
Mode and number of proofs:
`file_modification_time(+atom,-integer)` - `zero_or_one`

### `file_size/2`

File size (in bytes).

Compilation flags:
`static`
Template:
`file_size(File,Size)`
Mode and number of proofs:
`file_size(+atom,-integer)` - `zero_or_one`

### `file_permission/2`

True if the specified file has the specified permission (read, write, or execute).

Compilation flags:
`static`
Template:
`file_permission(File,Permission)`
Mode and number of proofs:
`file_permission(+atom,?atom)` - `zero_or_one`

### `rename_file/2`

Renames a file or a directory.

Compilation flags:
`static`
Template:
`rename_file(Old,New)`
Mode and number of proofs:
`rename_file(+atom,+atom)` - `zero_or_one`

### `delete_file/1`

Deletes a file.

Compilation flags:
`static`
Template:
`delete_file(File)`
Mode and number of proofs:
`delete_file(+atom)` - `one`

### `environment_variable/2`

Returns an environment variable value. Fails if the variable does not exists.

Compilation flags:
`static`
Template:
`environment_variable(Variable,Value)`
Mode and number of proofs:
`environment_variable(+atom,?atom)` - `zero_or_one`

### `time_stamp/1`

Returns a system-dependent time stamp, which can be used for sorting, but should be regarded otherwise as an opaque term.

Compilation flags:
`static`
Template:
`time_stamp(Time)`
Mode and number of proofs:
`time_stamp(-ground)` - `one`

### `date_time/7`

Returns the current date and time.

Compilation flags:
`static`
Template:
`date_time(Year,Month,Day,Hours,Minutes,Seconds,Miliseconds)`
Mode and number of proofs:
`date_time(-integer,-integer,-integer,-integer,-integer,-integer,-integer)` - `one`

### `cpu_time/1`

System cpu time in seconds.

Compilation flags:
`static`
Template:
`cpu_time(Seconds)`
Mode and number of proofs:
`cpu_time(-number)` - `one`

### `wall_time/1`

Wall time in seconds.

Compilation flags:
`static`
Template:
`wall_time(Seconds)`
Mode and number of proofs:
`wall_time(-number)` - `one`

### `operating_system_type/1`

Operating system type. Possible values are “unix”, “windows”, and “unknown”.

Compilation flags:
`static`
Template:
`operating_system_type(Type)`
Mode and number of proofs:
`operating_system_type(?atom)` - `one`

### `command_line_arguments/1`

Returns a list with the command line arguments that occur after “–”.

Compilation flags:
`static`
Template:
`command_line_arguments(Arguments)`
Mode and number of proofs:
`command_line_arguments(-list(atom))` - `one`

### `sleep/1`

Suspends execution the given number of seconds.

Compilation flags:
`static`
Template:
`sleep(Seconds)`
Mode and number of proofs:
`sleep(+number)` - `one`

## Protected interface

(none)

## Private predicates

(none)

## Operators

(none)

## Remarks

(none)

See also

os, os_types