ps(1)

report a snapshot of the current processes. · man1 · English

PS(1) User Commands PS(1)

ps - report a snapshot of the current processes.

ps [options]

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.

ps -e
ps -ef
ps -eF
ps -ely
ps ax
ps axu
ps -ejH
ps axjf
ps -eLf
ps axms
ps -eo euser,ruser,suser,fuser,f,comm,label
ps axZ
ps -eM
ps -U root -u root u
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
ps -C syslogd -o pid=
ps -q 42 -o comm=

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.
Select all processes. Identical to -e.
Select all processes except both session leaders (see getsid(2)) and processes not associated with a terminal.
Select all processes except session leaders.
Select all processes except those that fulfill the specified conditions (negates the selection). Identical to -N.
Select all processes. Identical to -A.
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.
Select all processes except those that fulfill the specified conditions (negates the selection). Identical to --deselect.
Select all processes associated with this terminal. Identical to the t option without any argument.
Restrict the selection to only running processes.
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.

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).
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.
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).
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.
Select by real group ID (RGID) or name. Identical to -G.
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.
Select by process ID. Identical to -p and --pid.
Select by PID. This selects the processes whose process ID numbers appear in pidlist. Identical to p and --pid.
Select by process ID. Identical to -p and p.
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.
Select by process ID (quick mode). Identical to -q and --quick-pid.
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.
Select by process ID (quick mode). Identical to -q and q.
Select by session ID. This selects the processes with a session ID specified in sesslist.
Select by session ID. Identical to -s.
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.
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.
Select by terminal. Identical to -t and t.
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.
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).
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.

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

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

Show different scheduler information for the -l option.
Display security context format (for SELinux).
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.
Extra full format. See the -f option, which -F implies.
user-defined format. Identical to -o and o.
BSD job control format.
Jobs format.
Display BSD long format.
Long format. The -y option is often useful with this.
Add a column of security data. Identical to Z (for SELinux).
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.
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.
Specify user-defined format. Identical to -o and --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.
Add a column showing psr.
Display signal format.
Display user-oriented format.
Display virtual memory format.
Register format.
Do not show flags; show rss in place of addr. This option can only be used with -l.
Add a column of security data. Identical to -M (for SELinux).

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.
Set screen width.
Set screen width.
Include some dead child process data (as a sum with the parent).
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.
Identical to -D.
Show the environment after the command.
ASCII art process hierarchy (forest).
ASCII art process tree.
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.
Show process hierarchy (forest).
Repeat header lines, one per page of output.
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
Set screen height.
Numeric output for WCHAN and USER (including all types of UID and GID).
Print no header line at all. --no-heading is an alias for this option.
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.
Set screen height.
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.
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
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.
Wide output. Use this option twice for unlimited width.
Wide output. Use this option twice for unlimited width.
Set screen width.

Show threads as if they were processes.
Show threads, possibly with LWP and NLWP columns.
Show threads after processes.
Show threads after processes.
Show threads, possibly with SPID column.

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.
Print debugging info.
List all format specifiers.
Print the procps-ng version.
Print the procps-ng version.
Print the procps-ng version.

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".

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

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:

uninterruptible sleep (usually IO)
Idle kernel thread
running or runnable (on run queue)
interruptible sleep (waiting for an event to complete)
stopped by job control signal
stopped by debugger during the tracing
paging (not valid since the 2.6.xx kernel)
dead (should never be seen)
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)
low-priority (nice to other users)
has pages locked into memory (for real-time and custom IO)
is a session leader
is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+
is in the foreground process group

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

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

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 pcpu ).
%mem %MEM ratio of the process's resident set size to the physical memory on the machine, expressed as a percentage. (alias pmem ).
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, ps will instead print the executable name in brackets. (alias cmd ", " command ). See also the comm format keyword, the -f option, and the c option. When specified last, this column will extend to the edge of the display. If ps 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 TERM variable, and so on). The COLUMNS environment variable or --cols option may be used to exactly determine the width in this case. The w or -w option may be also be used to adjust width.
blocked BLOCKED mask of the blocked signals, see signal (7). 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 sig_block ", " sigmask ).
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 lstart ,  start ,  start_time ", and"  stime .
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 %cpu ).
caught CAUGHT mask of the caught signals, see signal (7). 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 sig_catch ", " sigcatch ).
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 namespaces (7).
class CLS scheduling class of the process. (alias policy ", " cls ). Field's possible values are: +9n - 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 policy ", " cls ). Field's possible values are: +9n - 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 args . (alias args ", " command ).
comm COMMAND command name (only the executable name). The output in this column may contain spaces. (alias ucmd ", " ucomm ). See also the args format keyword, the -f option, and the c option. When specified last, this column will extend to the edge of the display. If ps 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 TERM variable, and so on). The COLUMNS environment variable or --cols option may be used to exactly determine the width in this case. The w  or  -w option may be also be used to adjust width.
command COMMAND See args . (alias args ", " command ).
cp CP per-mill (tenths of a percent) CPU usage. (see %cpu ).
cputime TIME cumulative CPU time, "[DD-]hh:mm:ss" format. (alias time ).
cputimes TIME cumulative CPU time in seconds (alias times ).
cuc %CUC The CPU utilization of a process, including dead children, in an extended "##.###" format. (see also %cpu , c , cp , cuu , pcpu ).
cuu %CUU The CPU utilization of a process in an extended "##.###" format. (see also %cpu , c , cp , cuc , pcpu ).
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 rss but will always be included included in the vsz amount.
egid EGID effective group ID number of the process as a decimal integer. (alias gid ).
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 group ).
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 uid ).
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 n option can be used to force the decimal representation. (alias uname ", " user ).
exe EXE path to the executable. Useful if path cannot be printed via cmd ", " comm or args format options.
f F flags associated with the process, see the PROCESS FLAGS section. (alias flag ", " flags ).
fgid FGID filesystem access group ID. (alias fsgid ).
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 fsgroup ).
flag F see f . (alias f ", " flags ).
flags F see f . (alias f ", " flag ).
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 fsuid ).
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 egid . (alias egid ).
group GROUP see egroup . (alias egroup ).
ignored IGNORED mask of the ignored signals, see signal (7). 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 sig_ignore ", " sigignore ).
ipcns IPCNS Unique inode number describing the namespace the process belongs to. See namespaces (7).
label LABEL security label, most commonly used for SELinux context data. This is for the Mandatory Access Control ("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 spid ,  tid ). See tid 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 namespaces (7).
netns NETNS Unique inode number describing the namespace the process belongs to. See namespaces (7).
ni NI nice value. This ranges from 19 (nicest) to -20 (not nice to others), see nice (1). (alias nice ).
nice NI see ni . (alias ni ).
nlwp NLWP number of lwps (threads) in the process. (alias thcount ).
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 wchan 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 %cpu . (alias %cpu ).
pending PENDING mask of the pending signals. See signal (7). Signals pending on the process are distinct from signals pending on individual threads. Use the m option or the -m 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 sig ).
pgid PGID process group ID or, equivalently, the process ID of the process group leader. (alias pgrp ).
pgrp PGRP see pgid . (alias pgid ).
pid PID a number representing the process ID (alias tgid ).
pidns PIDNS Unique inode number describing the namespace the process belongs to. See namespaces (7).
pmem %MEM see %mem . (alias %mem ).
policy POL scheduling class of the process. (alias class ", " cls ). Possible values are: +9n - 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 read "(2) and " pread (2).
rss RSS resident set size, the non-swapped physical memory that a task has used (in kilobytes). (alias rssize ", " rsz ).
rssize RSS see rss . (alias rss ", " rsz ).
rsz RSZ see rss . (alias rss ", " rssize ).
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 PROCESS STATE CODES for the different values. See also stat if you want additional information displayed. (alias state ).
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 session ", " sid ).
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 svgid ).
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 sess . (alias sess ", " session ).
sig PENDING see pending . (alias pending ", " sig_pend ).
sigcatch CAUGHT see caught . (alias caught ", " sig_catch ).
sigignore IGNORED see ignored . (alias ignored ", " sig_ignore ).
sigmask BLOCKED see blocked . (alias blocked ", " sig_block ).
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 lwp . (alias lwp ", " tid ).
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 bsdstart ", " start ", " start_time ", and " stime .
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 ps was invoked, or "MmmDD" if it was not started the same day, or "HH:MM" otherwise. See also bsdstart ", " start ", " lstart ", and " stime .
stat STAT multi-character process state. See section PROCESS STATE CODES for the different values meaning. See also s  and  state if you just want the first character displayed.
state S see s ". (alias"  s ).
stime STIME see start_time. (alias start_time).
suid SUID saved user ID. (alias svuid ).
supgid SUPGID group ids of supplementary groups, if any. See getgroups (2).
supgrp SUPGRP group names of supplementary groups, if any. See getgroups (2).
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 svuser ).
svgid SVGID see sgid . (alias sgid ).
svuid SVUID see suid . (alias suid ).
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 vsz  and  rss .
tgid TGID a number representing the thread group to which a task belongs (alias pid ). It is the process ID of the thread group leader.
thcount THCNT see nlwp . (alias nlwp ). number of kernel threads owned by the process.
tid TID the unique number representing a dispatchable entity (alias spid ", " tid ). 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 cputime ).
timens TIMENS Unique inode number describing the namespace the process belongs to. See namespaces (7).
times TIME cumulative CPU time in seconds (alias cputimes ).
tname TTY controlling tty (terminal). (alias tt ", " tty ).
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 tname ", " tty ).
tty TT controlling tty (terminal). (alias tname ", " tt ).
ucmd CMD see comm . (alias comm ", " ucomm ).
ucomm COMMAND see comm . (alias comm ", " ucmd ).
uid UID see euid . (alias euid ).
uname USER see euser . (alias euser ", " user ).
unit UNIT displays unit which a process belongs to, if systemd support has been included.
user USER see euser . (alias euser ", " uname ).
userns USERNS Unique inode number describing the namespace the process belongs to. See namespaces (7).
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 namespaces (7).
uunit UUNIT displays user unit which a process belongs to, if systemd support has been included.
vsize VSZ see vsz . (alias vsz ).
vsz VSZ virtual memory size of the process in KiB (1024-byte units). Device mappings are currently excluded; this is subject to change. (alias vsize ).
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 write "(2) and " pwrite (2).

The following environment variables could affect ps:

Override default display width.
Override default display height.
Set to one of posix, old, linux, bsd, sun, digital... (see section PERSONALITY below).
Set to one of posix, old, linux, bsd, sun, digital... (see section PERSONALITY below).
Force obsolete command line interpretation.
Date format.
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.
Not currently supported.
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.
Don't find excuses to ignore bad "features".
When set to "on", acts as POSIXLY_CORRECT.
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.

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

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.

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

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

ps was originally written by Branko Lankester. Michael K. Johnson re-wrote it significantly to use the proc filesystem, changing a few things in the process. Michael Shields added the pid-list feature. Charles Blake 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 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.

2023-08-19 procps-ng