PS(1)

NAME
ps - report a snapshot of the current processes.

SYNOPSIS
ps [options]

DESCRIPTION
ps displays information about a selection of the active processes. If you want a repetitive update of the selection and the displayed information, use top instead.

This version of ps accepts several kinds of options:

1   UNIX options, which may be grouped and must be preceded by a dash.
2   BSD options, which may be grouped and must not be used with a dash.
3   GNU long options, which are preceded by two dashes.

Options of different types may be freely mixed, but conflicts can appear. There are some synonymous options, which are functionally identical, due to the many standards and ps implementations that this ps is compatible with.

By default, ps selects all processes with the same effective user ID (euid=EUID) as the current user and associated with the same terminal as the invoker. It displays the process ID (pid=PID), the terminal associated with the process (tname=TTY), the cumulated CPU time in [DD-]hh:mm:ss format (time=TIME), and the executable name (ucmd=CMD). Output is unsorted by default.

The use of BSD-style options will add process state (stat=STAT) to the default display and show the command args (args=COMMAND) instead of the executable name. You can override this with the PS_FORMAT environment variable. The use of BSD-style options will also change the process selection to include processes on other terminals (TTYs) that are owned by you; alternately, this may be described as setting the selection to be the set of all processes filtered to exclude processes owned by other users or not on a terminal. These effects are not considered when options are described as being "identical" below, so -M will be considered identical to Z and so on.

Except as described below, process selection options are additive. The default selection is discarded, and then the selected processes are added to the set of processes to be displayed. A process will thus be shown if it meets any of the given selection criteria.

EXAMPLES

To see every process on the system using standard syntax:
    ps -e
    ps -ef
    ps -eF
    ps -ely

To see every process on the system using BSD syntax:
    ps ax
    ps axu

To print a process tree:
    ps -ejH
    ps axjf

To get info about threads:
    ps -eLf
    ps axms

To get security info:
    ps -eo euser,ruser,suser,fuser,f,comm,label
    ps axZ
    ps -eM

To see every process running as root (real & effective ID) in user format:
    ps -U root -u root u

To see every process with a user-defined format:
    ps -eo pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,wchan:14,comm
    ps axo stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm
    ps -Ao pid,tt,user,fname,tmout,f,wchan

Print only the process IDs of syslogd:
    ps -C syslogd -o pid=

Print only the name of PID 42:
    ps -q 42 -o comm=

SIMPLE PROCESS SELECTION

a   Lift the BSD-style "only yourself" restriction, which is imposed upon the set of all processes when some BSD-style (without "-") options are used or when the ps personality setting is BSD-like. The set of processes selected in this manner is in addition to the set of processes selected by other means. An alternate description is that this option causes ps to list all processes with a terminal (tty), or to list all processes when used together with the x option.

-A  Select all processes. Identical to -e.

-a  Select all processes except both session leaders (see getsid(2)) and processes not associated with a terminal.

-d  Select all processes except session leaders.

--deselect
    Select all processes except those that fulfill the specified conditions (negates the selection). Identical to -N.

-e  Select all processes. Identical to -A.

g   Really all, even session leaders. This flag is obsolete and may be discontinued in a future release. It is normally implied by the a flag, and is only useful when operating in the sunos4 personality.

-N  Select all processes except those that fulfill the specified conditions (negates the selection). Identical to --deselect.

T   Select all processes associated with this terminal. Identical to the t option without any argument.

r   Restrict the selection to only running processes.

x   Lift the BSD-style "must have a tty" restriction, which is imposed upon the set of all processes when some BSD-style (without "-") options are used or when the ps personality setting is BSD-like. The set of processes selected in this manner is in addition to the set of processes selected by other means. An alternate description is that this option causes ps to list all processes owned by you (same EUID as ps), or to list all processes when used together with the a option.

PROCESS SELECTION BY LIST
These options accept a single argument in the form of a blank-separated or comma-separated list. They can be used multiple times. For example: ps -p "1 2" -p 3,4

123 Identical to --pid 123.

+123
    Identical to --sid 123.

-123
    Select by process group ID (PGID).

-C cmdlist
    Select by command name. This selects the processes whose executable name is given in cmdlist. NOTE: The command name is not the same as the command line. Previous versions of procps and the kernel truncated this command name to 15 characters. This limitation is no longer present in both. If you depended on matching only 15 characters, you may no longer get a match.

-G grplist
    Select by real group ID (RGID) or name. This selects the processes whose real group name or ID is in the grplist list. The real group ID identifies the group of the user who created the process, see getgid(2).

-g grplist
    Select by session OR by effective group name. Selection by session is specified by many standards, but selection by effective group is the logical behavior that several other operating systems use. This ps will select by session when the list is completely numeric (as sessions are). Group ID numbers will work only when some group names are also specified. See the -s and --group options.

--Group grplist
    Select by real group ID (RGID) or name. Identical to -G.

--group grplist
    Select by effective group ID (EGID) or name. This selects the processes whose effective group name or ID is in grplist. The effective group ID describes the group whose file access permissions are used by the process (see getegid(2)). The -g option is often an alternative to --group.

p pidlist
    Select by process ID. Identical to -p and --pid.

-p pidlist
    Select by PID. This selects the processes whose process ID numbers appear in pidlist. Identical to p and --pid.

--pid pidlist
    Select by process ID. Identical to -p and p.

--ppid pidlist
    Select by parent process ID. This selects the processes with a parent process ID in pidlist. That is, it selects processes that are children of those listed in pidlist.

q pidlist
    Select by process ID (quick mode). Identical to -q and --quick-pid.

-q pidlist
    Select by PID (quick mode). This selects the processes whose process ID numbers appear in pidlist. With this option ps reads the necessary info only for the pids listed in the pidlist and doesn't apply additional filtering rules. The order of pids is unsorted and preserved. No additional selection options, sorting and forest type listings are allowed in this mode. Identical to q and --quick-pid.

--quick-pid pidlist
    Select by process ID (quick mode). Identical to -q and q.

-s sesslist
    Select by session ID. This selects the processes with a session ID specified in sesslist.

--sid sesslist
    Select by session ID. Identical to -s.

t ttylist
    Select by tty. Nearly identical to -t and --tty, but can also be used with an empty ttylist to indicate the terminal associated with ps. Using the T option is considered cleaner than using t with an empty ttylist.

-t ttylist
    Select by tty. This selects the processes associated with the terminals given in ttylist. Terminals (ttys, or screens for text output) can be specified in several forms: /dev/ttyS1, ttyS1, S1. A plain "-" may be used to select processes not attached to any terminal.

--tty ttylist
    Select by terminal. Identical to -t and t.

U userlist
    Select by effective user ID (EUID) or name. This selects the processes whose effective user name or ID is in userlist. The effective user ID describes the user whose file access permissions are used by the process (see geteuid(2)). Identical to -u and --user.

-U userlist
    Select by real user ID (RUID) or name. It selects the processes whose real user name or ID is in the userlist list. The real user ID identifies the user who created the process, see getuid(2).

-u userlist
    Select by effective user ID (EUID) or name. This selects the processes whose effective user name or ID is in userlist. The effective user ID describes the user whose file access permissions are used by the process (see geteuid(2)). Identical to U and --user.

--User userlist
    Select by real user ID (RUID) or name. Identical to -U.

--user userlist
    Select by effective user ID (EUID) or name. Identical to -u and U.

OUTPUT FORMAT CONTROL
These options are used to choose the information displayed by ps. The output may differ by personality.

-c  Show different scheduler information for the -l option.

--context
    Display security context format (for SELinux).

-f  Do full-format listing. This option can be combined with many other UNIX-style options to add additional columns. It also causes the command arguments to be printed. When used with -L, the NLWP (number of threads) and LWP (thread ID) columns will be added. See the c option, the format keyword args, and the format keyword comm.

-F  Extra full format. See the -f option, which -F implies.

--format format
    user-defined format. Identical to -o and o.

j   BSD job control format.

-j  Jobs format.

l   Display BSD long format.

-l  Long format. The -y option is often useful with this.

-M  Add a column of security data. Identical to Z (for SELinux).

O format
    is preloaded o (overloaded). The BSD O option can act like -O (user-defined output format with some common fields predefined) or can be used to specify sort order. Heuristics are used to determine the behavior of this option. To ensure that the desired behavior is obtained (sorting or formatting), specify the option in some other way (e.g. with -O or --sort). When used as a formatting option, it is identical to -O, with the BSD personality.

-O format
    Like -o, but preloaded with some default columns. Identical to -o pid,format,state,tname,time,command or -o pid,format,tname,time,cmd, see -o below.

o format
    Specify user-defined format. Identical to -o and --format.

-o format
    User-defined format. format is a single argument in the form of a blank-separated or comma-separated list, which offers a way to specify individual output columns. The recognized keywords are described in the STANDARD FORMAT SPECIFIERS section below. Headers may be renamed (ps -o pid,ruser=RealUser -o comm=Command) as desired. If all column headers are empty (ps -o pid= -o comm=) then the header line will not be output. Column width will increase as needed for wide headers; this may be used to widen up columns such as WCHAN (ps -o pid,wchan=WIDE-WCHAN-COLUMN -o comm). Explicit width control (ps opid,wchan:42,cmd) is offered too. The behavior of ps -o pid=X,comm=Y varies with personality; output may be one column named "X,comm=Y" or two columns named "X" and "Y". Use multiple -o options when in doubt. Use the PS_FORMAT environment variable to specify a default as desired; DefSysV and DefBSD are macros that may be used to choose the default UNIX or BSD columns.

-P  Add a column showing psr.

s   Display signal format.

u   Display user-oriented format.

v   Display virtual memory format.

X   Register format.

-y  Do not show flags; show rss in place of addr. This option can only be used with -l.

Z   Add a column of security data. Identical to -M (for SELinux).

OUTPUT MODIFIERS

c   Show the true command name. This is derived from the name of the executable file, rather than from the argv value. Command arguments and any modifications to them are thus not shown. This option effectively turns the args format keyword into the comm format keyword; it is useful with the -f format option and with the various BSD-style format options, which all normally display the command arguments. See the -f option, the format keyword args, and the format keyword comm.

--cols n
    Set screen width.

--columns n
    Set screen width.

--cumulative
    Include some dead child process data (as a sum with the parent).

-D format
    Set the date format of the lstart field to format. This format is parsed by strftime(3) and should be a maximum of 24 characters to not mis-align columns.

--date-format format
    Identical to -D.

e   Show the environment after the command.

f   ASCII art process hierarchy (forest).

--forest
    ASCII art process tree.

h   No header. (or, one header per screen in the BSD personality). The h option is problematic. Standard BSD ps uses this option to print a header on each page of output, but older Linux ps uses this option to totally disable the header. This version of ps follows the Linux usage of not printing the header unless the BSD personality has been selected, in which case it prints a header on each page of output. Regardless of the current personality, you can use the long options --headers and --no-headers to enable printing headers each page or disable headers entirely, respectively.

-H  Show process hierarchy (forest).

--headers
    Repeat header lines, one per page of output.

k spec
    Specify sorting order. Sorting syntax is [+|-] key [,[+|-] key[,...]]. Choose a multi-letter key from the STANDARD FORMAT SPECIFIERS section. The "+" is optional since default direction is increasing numerical or lexicographic order. Identical to --sort.

        Examples:
        ps jaxkuid,-ppid,+pid
        ps axk comm o comm,args
        ps kstart_time -ef

--lines n
    Set screen height.

n   Numeric output for WCHAN and USER (including all types of UID and GID).

--no-headers
    Print no header line at all. --no-heading is an alias for this option.

O order
    Sorting order (overloaded). The BSD O option can act like -O (user-defined output format with some common fields predefined) or can be used to specify sort order. Heuristics are used to determine the behavior of this option. To ensure that the desired behavior is obtained (sorting or formatting), specify the option in some other way (e.g. with -O or --sort).

    For sorting, obsolete BSD O option syntax is O[+|-] k1[,[ +|-] k2[,...]]. It orders the processes listing according to the multilevel sort specified by the sequence of one-letter short keys k1,k2, ... described in the OBSOLETE SORT KEYS section below. The "+" is currently optional, merely re-iterating the default direction on a key, but may help to distinguish an O sort from an O format. The "-" reverses direction only on the key it precedes.

--rows n
    Set screen height.

S   Sum up some information, such as CPU usage, from dead child processes into their parent. This is useful for examining a system where a parent process repeatedly forks off short-lived children to do work.

--sort spec
    Specify sorting order. Sorting syntax is [+|-] key[,[ +|-] key[,...]]. Choose a multi-letter key from the STANDARD FORMAT SPECIFIERS section. The "+" is optional since default direction is increasing numerical or lexicographic order. Identical to k. For example: ps jax --sort=uid,-ppid,+pid

--signames
    Show signal masks using abbreviated signal names and expands the collumn. If the column width cannot show all signals, the column will end with a plus "+". Columns with only a hyphen have no signals.

w   Wide output. Use this option twice for unlimited width.

-w  Wide output. Use this option twice for unlimited width.

--width n
    Set screen width.

THREAD DISPLAY

H   Show threads as if they were processes.

-L  Show threads, possibly with LWP and NLWP columns.

m   Show threads after processes.

-m  Show threads after processes.

-T  Show threads, possibly with SPID column.

OTHER INFORMATION

--help section
    Print a help message. The section argument can be one of simple, list, output, threads, misc, or all. The argument can be shortened to one of the underlined letters as in: s|l|o|t|m|a.

--info
    Print debugging info.

L   List all format specifiers.

V   Print the procps-ng version.

-V  Print the procps-ng version.

--version
    Print the procps-ng version.

NOTES
This ps works by reading the virtual files in /proc. This ps does not need to be setuid kmem or have any privileges to run. Do not give this ps any special permissions.

CPU usage is currently expressed as the percentage of time spent running during the entire lifetime of a process. This is not ideal, and it does not conform to the standards that ps otherwise conforms to. CPU usage is unlikely to add up to exactly 100%.

The SIZE and RSS fields don't count some parts of a process including the page tables, kernel stack, struct thread_info, and struct task_struct. This is usually at least 20 KiB of memory that is always resident. SIZE is the virtual size of the process (code+data+stack).

Processes marked <defunct> are dead processes (so-called "zombies") that remain because their parent has not destroyed them properly. These processes will be destroyed by init(8) if the parent process exits.

If the length of the username is greater than the width of the display column, the username will be truncated. See the -o and -O formatting options to customize length.

Commands options such as ps -aux are not recommended as it is a confusion of two different standards. According to the POSIX and UNIX standards, the above command asks to display all processes with a TTY (generally the commands users are running) plus all processes owned by a user named x. If that user doesn't exist, then ps will assume you really meant "ps aux".

PROCESS FLAGS
The sum of these values is displayed in the "F" column, which is provided by the flags output specifier:

    1   forked but didn't exec
    4   used super-user privileges

PROCESS STATE CODES
Here are the different values that the s, stat and state output specifiers (header "STAT" or "S") will display to describe the state of a process:

    D   uninterruptible sleep (usually IO)
    I   Idle kernel thread
    R   running or runnable (on run queue)
    S   interruptible sleep (waiting for an event to complete)
    T   stopped by job control signal
    t   stopped by debugger during the tracing
    W   paging (not valid since the 2.6.xx kernel)
    X   dead (should never be seen)
    Z   defunct ("zombie") process, terminated but not reaped by its parent

For BSD formats and when the stat keyword is used, additional characters may be displayed:

    <   high-priority (not nice to other users)
    N   low-priority (nice to other users)
    L   has pages locked into memory (for real-time and custom IO)
    s   is a session leader
    l   is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
    +   is in the foreground process group

OBSOLETE SORT KEYS
These keys are used by the BSD O option (when it is used for sorting). The GNU --sort option doesn't use these keys, but the specifiers described below in the STANDARD FORMAT SPECIFIERS section. Note that the values used in sorting are the internal values ps uses and not the "cooked" values used in some of the output format fields (e.g. sorting on tty will sort into device number, not according to the terminal name displayed). Pipe ps output into the sort(1) command if you want to sort the cooked values.
KEY | LONG | DESCRIPTION
c | cmd | simple name of executable
C | pcpu | cpu utilization
f | flags | flags as in long format F field
g | pgrp | process group ID
G | tpgid | controlling tty process group ID
j | cutime | cumulative user time
J | cstime | cumulative system time
k | utime | user time
m | min_flt | number of minor page faults
M | maj_flt | number of major page faults
n | cmin_flt | cumulative minor page faults
N | cmaj_flt | cumulative major page faults
o | session | session ID
p | pid | process ID
P | ppid | parent process ID
r | rss | resident set size
R | resident | resident pages
s | size | memory size in kilobytes
S | share | amount of shared pages
t | tty | the device number of the controlling tty
T | start_time | time process was started
U | uid | user ID number
u | user | user name
v | vsize | total VM size in KiB
y | priority | kernel scheduling priority

AIX FORMAT DESCRIPTORS
This ps supports AIX format descriptors, which work somewhat like the formatting codes of printf(1) and printf(3). For example, the normal default output can be produced with this: ps -eo "%p %y %x %c". The NORMAL codes are described in the next section.
CODE | NORMAL | HEADER
%C | pcpu | %CPU
%G | group | GROUP
%P | ppid | PPID
%U | user | USER
%a | args | COMMAND
%c | comm | COMMAND
%g | rgroup | RGROUP
%n | nice | NI
%p | pid | PID
%r | pgid | PGID
%t | etime | ELAPSED
%u | ruser | RUSER
%x | time | TIME
%y | tty | TTY
%z | vsz | VSZ

STANDARD FORMAT SPECIFIERS
Here are the different keywords that may be used to control the output format (e.g., with option -o) or to sort the selected processes with the GNU-style --sort option.

For example: ps -eo pid,user,args --sort user

This version of ps tries to recognize most of the keywords used in other implementations of ps.

The following user-defined format specifiers may contain spaces: args, cmd, comm, command, fname, ucmd, ucomm, lstart, bsdstart, start.

Some keywords may not be available for sorting.
CODE | HEADER | DESCRIPTION
%cpu | %CPU | cpu utilization of the process in "##.#" format. Currently, it is the CPU time used divided by the time the process has been running (cputime/realtime ratio), expressed as a percentage. It will not add up to 100% unless you are lucky. (alias
%mem | %MEM | ratio of the process's resident set size to the physical memory on the machine, expressed as a percentage. (alias
ag_id | AGID | The autogroup identifier associated with a process which operates in conjunction with the CFS scheduler to improve interactive desktop performance.
ag_nice | AGNI | The autogroup nice value which affects scheduling of all processes in that group.
args | COMMAND | command with all its arguments as a string. Modifications to the arguments may be shown. The output in this column may contain spaces. A process marked <defunct> is partly dead, waiting to be fully destroyed by its parent. Sometimes the process args will be unavailable; when this happens, will instead print the executable name in brackets. (alias See also the format keyword, the option, and the option. When specified last, this column will extend to the edge of the display. If can not determine display width, as when output is redirected (piped) into a file or another command, the output width is undefined (it may be 80, unlimited, determined by the variable, and so on). The environment variable or option may be used to exactly determine the width in this case. The or option may be also be used to adjust width.
blocked | BLOCKED | mask of the blocked signals, see According to the width of the field, a 32 or 64-bit mask in hexadecimal format is displayed, unless the --signames option is used. (alias
bsdstart | START | time the command started. If the process was started less than 24 hours ago, the output format is " HH:MM", else it is " Mmm:SS" (where Mmm is the three letters of the month). See also
bsdtime | TIME | accumulated cpu time, user + system. The display format is usually "MMM:SS", but can be shifted to the right if the process used more than 999 minutes of cpu time.
c | C | processor utilization. Currently, this is the integer value of the percent usage over the lifetime of the process. (see
caught | CAUGHT | mask of the caught signals, see According to the width of the field, a 32 or 64 bits mask in hexadecimal format is displayed, unless the --signames option is used. (alias
cgname | CGNAME | display name of control groups to which the process belongs.
cgroup | CGROUP | display control groups to which the process belongs.
cgroupns | CGROUPNS | Unique inode number describing the namespace the process belongs to. See
class | CLS | scheduling class of the process. (alias Field's possible values are: - not reported TS SCHED_OTHER FF SCHED_FIFO RR SCHED_RR B SCHED_BATCH ISO SCHED_ISO IDL SCHED_IDLE DLN SCHED_DEADLINE ? unknown value
cls | CLS | scheduling class of the process. (alias Field's possible values are: - not reported TS SCHED_OTHER FF SCHED_FIFO RR SCHED_RR B SCHED_BATCH ISO SCHED_ISO IDL SCHED_IDLE DLN SCHED_DEADLINE ? unknown value
cmd | CMD | see (alias
comm | COMMAND | command name (only the executable name). The output in this column may contain spaces. (alias See also the format keyword, the option, and the option. When specified last, this column will extend to the edge of the display. If can not determine display width, as when output is redirected (piped) into a file or another command, the output width is undefined (it may be 80, unlimited, determined by the variable, and so on). The environment variable or option may be used to exactly determine the width in this case. The option may be also be used to adjust width.
command | COMMAND | See (alias
cp | CP | per-mill (tenths of a percent) CPU usage. (see
cputime | TIME | cumulative CPU time, "[DD-]hh:mm:ss" format. (alias
cputimes | TIME | cumulative CPU time in seconds (alias
cuc | %CUC | The CPU utilization of a process, including dead children, in an extended "##.###" format. (see also
cuu | %CUU | The CPU utilization of a process in an extended "##.###" format. (see also
drs | DRS | data resident set size, the amount of private memory reserved by a process. It is also known as DATA. Such memory may not yet be mapped to but will always be included included in the amount.
egid | EGID | effective group ID number of the process as a decimal integer. (alias
egroup | EGROUP | effective group ID of the process. This will be the textual group ID, if it can be obtained and the field width permits, or a decimal representation otherwise. (alias
eip | EIP | instruction pointer. As of kernel 4.9.xx will be zeroed out unless task is exiting or being core dumped.
esp | ESP | stack pointer. As of kernel 4.9.xx will be zeroed out unless task is exiting or being core dumped.
etime | ELAPSED | elapsed time since the process was started, in the form [[DD-]hh:]mm:ss.
etimes | ELAPSED | elapsed time since the process was started, in seconds.
euid | EUID | effective user ID (alias
euser | EUSER | effective user name. This will be the textual user ID, if it can be obtained and the field width permits, or a decimal representation otherwise. The option can be used to force the decimal representation. (alias
exe | EXE | path to the executable. Useful if path cannot be printed via or format options.
f | F | flags associated with the process, see the section. (alias
fgid | FGID | filesystem access group ID. (alias
fgroup | FGROUP | filesystem access group ID. This will be the textual group ID, if it can be obtained and the field width permits, or a decimal representation otherwise. (alias
flag | F | see (alias
flags | F | see (alias
fname | COMMAND | first 8 bytes of the base name of the process's executable file. The output in this column may contain spaces.
fuid | FUID | filesystem access user ID. (alias
fuser | FUSER | filesystem access user ID. This will be the textual user ID, if it can be obtained and the field width permits, or a decimal representation otherwise.
gid | GID | see (alias
group | GROUP | see (alias
ignored | IGNORED | mask of the ignored signals, see According to the width of the field, a 32 or 64 bits mask in hexadecimal format is displayed, unless the --signames option is used. (alias
ipcns | IPCNS | Unique inode number describing the namespace the process belongs to. See
label | LABEL | security label, most commonly used for SELinux context data. This is for the ("MAC") found on high-security systems.
lstart | STARTED | time the command started. This will be in the form "DDD mmm HH:MM:SS YYY" unless changed by the -D option.
lsession | SESSION | displays the login session identifier of a process, if systemd support has been included.
luid | LUID | displays Login ID associated with a process.
lwp | LWP | light weight process (thread) ID of the dispatchable entity (alias See for additional information.
lxc | LXC | The name of the lxc container within which a task is running. If a process is not running inside a container, a dash ('-') will be shown.
machine | MACHINE | displays the machine name for processes assigned to VM or container, if systemd support has been included.
maj_flt | MAJFLT | The number of major page faults that have occurred with this process.
min_flt | MINFLT | The number of minor page faults that have occurred with this process.
mntns | MNTNS | Unique inode number describing the namespace the process belongs to. See
netns | NETNS | Unique inode number describing the namespace the process belongs to. See
ni | NI | nice value. This ranges from 19 (nicest) to -20 (not nice to others), see (alias
nice | NI | see
nlwp | NLWP | number of lwps (threads) in the process. (alias
numa | NUMA | The node associated with the most recently used processor. A -1 means that NUMA information is unavailable.
nwchan | WCHAN | address of the kernel function where the process is sleeping (use if you want the kernel function name).
oom | OOM | Out of Memory Score. The value, ranging from 0 to +1000, used to select task(s) to kill when memory is exhausted.
oomadj | OOMADJ | Out of Memory Adjustment Factor. The value is added to the current out of memory score which is then used to determine which task to kill when memory is exhausted.
ouid | OWNER | displays the Unix user identifier of the owner of the session of a process, if systemd support has been included.
pcpu | %CPU | see (alias
pending | PENDING | mask of the pending signals. See Signals pending on the process are distinct from signals pending on individual threads. Use the option or the option to see both. According to the width of the field, a 32 or 64 bits mask in hexadecimal format is displayed, unless the --signames option is used. (alias
pgid | PGID | process group ID or, equivalently, the process ID of the process group leader. (alias
pgrp | PGRP | see (alias
pid | PID | a number representing the process ID (alias
pidns | PIDNS | Unique inode number describing the namespace the process belongs to. See
pmem | %MEM | see (alias
policy | POL | scheduling class of the process. (alias Possible values are: - not reported TS SCHED_OTHER FF SCHED_FIFO RR SCHED_RR B SCHED_BATCH ISO SCHED_ISO IDL SCHED_IDLE DLN SCHED_DEADLINE ? unknown value
ppid | PPID | parent process ID.
pri | PRI | priority of the process. Higher number means higher priority.
psr | PSR | processor that process last executed on.
pss | PSS | Proportional share size, the non-swapped physical memory, with shared memory proportionally accounted to all tasks mapping it.
rbytes | RBYTES | Number of bytes which this process really did cause to be fetched from the storage layer.
rchars | RCHARS | Number of bytes which this task has caused to be read from storage.
rgid | RGID | real group ID.
rgroup | RGROUP | real group name. This will be the textual group ID, if it can be obtained and the field width permits, or a decimal representation otherwise.
rops | ROPS | Number of read I/O operations—that is, system calls such as
rss | RSS | resident set size, the non-swapped physical memory that a task has used (in kilobytes). (alias
rssize | RSS | see (alias
rsz | RSZ | see (alias
rtprio | RTPRIO | realtime priority.
ruid | RUID | real user ID.
ruser | RUSER | real user ID. This will be the textual user ID, if it can be obtained and the field width permits, or a decimal representation otherwise.
s | S | minimal state display (one character). See section for the different values. See also if you want additional information displayed. (alias
sched | SCH | scheduling policy of the process. The policies SCHED_OTHER (SCHED_NORMAL), SCHED_FIFO, SCHED_RR, SCHED_BATCH, SCHED_ISO, SCHED_IDLE and SCHED_DEADLINE are respectively displayed as 0, 1, 2, 3, 4, 5 and 6.
seat | SEAT | displays the identifier associated with all hardware devices assigned to a specific workplace, if systemd support has been included.
sess | SESS | session ID or, equivalently, the process ID of the session leader. (alias
sgi_p | P | processor that the process is currently executing on. Displays "*" if the process is not currently running or runnable.
sgid | SGID | saved group ID. (alias
sgroup | SGROUP | saved group name. This will be the textual group ID, if it can be obtained and the field width permits, or a decimal representation otherwise.
sid | SID | see (alias
sig | PENDING | see (alias
sigcatch | CAUGHT | see (alias
sigignore | IGNORED | see (alias
sigmask | BLOCKED | see (alias
size | SIZE | approximate amount of swap space that would be required if the process were to dirty all writable pages and then be swapped out. This number is very rough!
slice | SLICE | displays the slice unit which a process belongs to, if systemd support has been included.
spid | SPID | see (alias
stackp | STACKP | address of the bottom (start) of stack for the process.
start | STARTED | time the command started. If the process was started less than 24 hours ago, the output format is "HH:MM:SS", else it is " Mmm dd" (where Mmm is a three-letter month name). See also
start_time | START | starting time or date of the process. Only the year will be displayed if the process was not started the same year was invoked, or "MmmDD" if it was not started the same day, or "HH:MM" otherwise. See also
stat | STAT | multi-character process state. See section for the different values meaning. See also if you just want the first character displayed.
state | S | see
stime | STIME | see start_time. (alias start_time).
suid | SUID | saved user ID. (alias
supgid | SUPGID | group ids of supplementary groups, if any. See
supgrp | SUPGRP | group names of supplementary groups, if any. See
suser | SUSER | saved user name. This will be the textual user ID, if it can be obtained and the field width permits, or a decimal representation otherwise. (alias
svgid | SVGID | see (alias
svuid | SVUID | see (alias
sz | SZ | size in physical pages of the core image of the process. This includes text, data, and stack space. Device mappings are currently excluded; this is subject to change. See
tgid | TGID | a number representing the thread group to which a task belongs (alias It is the process ID of the thread group leader.
thcount | THCNT | see (alias number of kernel threads owned by the process.
tid | TID | the unique number representing a dispatchable entity (alias This value may also appear as: a process ID (pid); a process group ID (pgrp); a session ID for the session leader (sid); a thread group ID for the thread group leader (tgid); and a tty process group ID for the process group leader (tpgid).
time | TIME | cumulative CPU time, "[DD-]HH:MM:SS" format. (alias
timens | TIMENS | Unique inode number describing the namespace the process belongs to. See
times | TIME | cumulative CPU time in seconds (alias
tname | TTY | controlling tty (terminal). (alias
tpgid | TPGID | ID of the foreground process group on the tty (terminal) that the process is connected to, or -1 if the process is not connected to a tty.
trs | TRS | text resident set size, the amount of physical memory devoted to executable code.
tt | TT | controlling tty (terminal). (alias
tty | TT | controlling tty (terminal). (alias
ucmd | CMD | see (alias
ucomm | COMMAND | see (alias
uid | UID | see (alias
uname | USER | see (alias
unit | UNIT | displays unit which a process belongs to, if systemd support has been included.
user | USER | see (alias
userns | USERNS | Unique inode number describing the namespace the process belongs to. See
uss | USS | Unique set size, the non-swapped physical memory, which is not shared with an another task.
utsns | UTSNS | Unique inode number describing the namespace the process belongs to. See
uunit | UUNIT | displays user unit which a process belongs to, if systemd support has been included.
vsize | VSZ | see (alias
vsz | VSZ | virtual memory size of the process in KiB (1024-byte units). Device mappings are currently excluded; this is subject to change. (alias
wbytes | WBYTES | Number of bytes which this process caused to be sent to the storage layer.
wcbytes | WCBYTES | Number of cancelled write bytes.
wchan | WCHAN | name of the kernel function in which the process is sleeping.
wchars | WCHARS | Number of bytes which this task has caused, or shall cause to be written to disk.
wops | WOPS | Number of write I/O operations—that is, system calls such as

ENVIRONMENT VARIABLES
The following environment variables could affect ps:

COLUMNS
    Override default display width.

LINES
    Override default display height.

PS_PERSONALITY
    Set to one of posix, old, linux, bsd, sun, digital... (see section PERSONALITY below).

CMD_ENV
    Set to one of posix, old, linux, bsd, sun, digital... (see section PERSONALITY below).

I_WANT_A_BROKEN_PS
    Force obsolete command line interpretation.

LC_TIME
    Date format.

LIBPROC_HIDE_KERNEL
    Set this to any value to hide kernel threads normally displayed with the -e option. This is equivalent to selecting --ppid 2 -p 2 --deselect instead. Also works in BSD mode.

PS_COLORS
    Not currently supported.

PS_FORMAT
    Default output format override. You may set this to a format string of the type used for the -o option. The DefSysV and DefBSD values are particularly useful.

POSIXLY_CORRECT
    Don't find excuses to ignore bad "features".

POSIX2
    When set to "on", acts as POSIXLY_CORRECT.

UNIX95
    Don't find excuses to ignore bad "features".

_XPG
    Cancel CMD_ENV= irix non-standard behavior.

In general, it is a bad idea to set these variables. The one exception is CMD_ENV or PS_PERSONALITY, which could be set to Linux for normal systems. Without that setting, ps follows the useless and bad parts of the Unix98 standard.

PERSONALITY
390 | like the OS/390 OpenEdition ps
aix | like AIX ps
bsd | like FreeBSD ps (totally non-standard)
compaq | like Digital Unix ps
debian | like the old Debian ps
digital | like Tru64 (was Digital Unix, was OSF/1) ps
gnu | like the old Debian ps
hp | like HP-UX ps
hpux | like HP-UX ps
irix | like Irix ps
linux | ***** recommended *****
old | like the original Linux ps (totally non-standard)
os390 | like OS/390 Open Edition ps
posix | standard
s390 | like OS/390 Open Edition ps
sco | like SCO ps
sgi | like Irix ps
solaris2 | like Solaris 2+ (SunOS 5) ps
sunos4 | like SunOS 4 (Solaris 1) ps (totally non-standard)
svr4 | standard
sysv | standard
tru64 | like Tru64 (was Digital Unix, was OSF/1) ps
unix | standard
unix95 | standard
unix98 | standard

BUGS
The fields bsdstart and start will only show the abbreviated month name in English. The fields lstart and stime will show the abbreviated month name in the configured locale but may exceed the column width due to the different lengths for abbreviated month and day names across languages.

SEE ALSO
pgrep(1), pstree(1), top(1), strftime(3), proc(5).

STANDARDS
This ps conforms to:

1   Version 2 of the Single Unix Specification
2   The Open Group Technical Standard Base Specifications, Issue 6
3   IEEE Std 1003.1, 2004 Edition
4   X/Open System Interfaces Extension [UP XSI]
5   ISO/IEC 9945:2003

AUTHOR
ps was originally written by Branko Lankester (lankeste@fwi.uva.nl). Michael K. Johnson (johnsonm@redhat.com) re-wrote it significantly to use the proc filesystem, changing a few things in the process. Michael Shields (mjshield@nyx.cs.du.edu) added the pid-list feature. Charles Blake (cblake@bbn.com) added multi-level sorting, the dirent-style library, the device name-to-number mmaped database, the approximate binary search directly on System.map, and many code and documentation cleanups. David Mossberger-Tang wrote the generic BFD support for psupdate. Albert Cahalan (albert@users.sf.net) rewrote ps for full Unix98 and BSD support, along with some ugly hacks for obsolete and foreign syntax.

Please send bug reports to procps@freelists.org. No subscription is required or suggested.