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PS   (1) manpage
PS
1
March 11, 1999
Linux
Linux User's Manual
  • NAME
      ps - report process status
  • SYNOPSIS
      ps [options]
  • DESCRIPTION
      ps(1) gives a snapshot of the current processes. If you want a repetitive update of this status, use top.
  • COMMAND-LINE OPTIONS

      This version of ps accepts several kinds of options.
      Unix98 options may be grouped and must be preceeded by a dash.
      BSD options may be grouped and must not be used with a dash.
      GNU long options are preceeded by two dashes.

      Options of different types may be freely mixed.
      Set the I_WANT_A_BROKEN_PS environment variable to force BSD syntax even when options are preceeded by a dash. The PS_PERSONALITY environment variable (described below) provides more detailed control of ps behavior.
      "SIMPLE PROCESS SELECTION"
      lfCW l.
      Switch Description
      .TH
      -A select all processes
      -N negate selection
      -a select all with a tty except session leaders
      -d select all, but omit session leaders
      -e select all processes
      T select all processes on this terminal
      a T{
      select all processes on a terminal, including those of other users
      T}
      g T{
      really all, even group leaders (does nothing w/o SunOS settings)
      T}
      r restrict output to running processes
      x select processes without controlling ttys
      --deselect negate selection

      "PROCESS SELECTION BY LIST"
      lfCW l.
      Switch Description
      .TH
      -C select by command name
      -G select by RGID (supports names)
      -U select by RUID (supports names)
      -g select by session leader OR by group name
      -p select by PID
      -s select processes belonging to the sessions given
      -t select by tty
      -u select by effective user ID (supports names)
      U select processes for specified users
      p select by process ID
      t select by tty
      --Group select by real group name or ID
      --User select by real user name or ID
      --group select by effective group name or ID
      --pid select by process ID
      --sid select by session ID
      --tty select by terminal
      --user select by effective user name or ID
      -123 implied --sid
      123 implied --pid

      "OUTPUT FORMAT CONTROL"
      lfCW l.
      Switch Description
      .TH
      -O is preloaded "-o"
      -c different scheduler info for -l option
      -f does full listing
      -j jobs format
      -l long format
      -o user-defined format
      -y do not show flags; show rss in place of addr
      O is preloaded "o" (overloaded)
      X old Linux i386 register format
      j job control format
      l display long format
      o specify user-defined format
      s display signal format
      u display user-oriented format
      v display virtual memory format
      --format user-defined format

      "OUTPUT MODIFIERS"
      lfCW l.
      Switch Description
      .TH
      -H show process hierarchy (forest)
      -m show all threads
      -n set namelist file
      -w wide output
      C use raw CPU time for %CPU instead of decaying average
      N specify namelist file
      O sorting order (overloaded)
      S T{
      include some dead child process data (as a sum with the parent)
      T}
      c true command name
      e show environment after the command
      f ASCII-art process hierarchy (forest)
      h T{
      do not print header lines (repeat header lines in BSD personality)
      T}
      m all threads
      n numeric output for WCHAN and USER
      w wide output
      --cols set screen width
      --columns set screen width
      --cumulative T{
      include some dead child process data (as a sum with the parent)
      T}
      --forest ASCII art process tree
      --html HTML escaped output
      --headers repeat header lines
      --no-headers print no header line at all
      --lines set screen height
      --nul unjustified output with NULs
      --null unjustified output with NULs
      --rows set screen height
      --sort specify sorting order
      --width set screen width
      --zero unjustified output with NULs

      INFORMATION
      lfCW l.
      Switch Description
      .TH
      -V print version
      L list all format specifiers
      V show version info
      --help print help message
      --info print debugging info
      --version print version

      OBSOLETE
      lfCW l.
      Switch Description
      .TH
      A increase the argument space (DecUnix)
      M use alternate core (try -n or N instead)
      W get swap info from ... not /dev/drum (try -n or N instead)
      k use /vmcore as c-dumpfile (try -n or N instead)

  • NOTES

      The "-g" option can select by session leader OR by group name. Selection by session leader is specified by many standards, but selection by group is the logical behavior that several other operating systems use. This ps will select by session leader when the list is completely numeric (as sessions are). Group ID numbers will work only when some group names are also specified.
      The "m" option should not be used. Use "-m" or "-o" with a list. ("m" displays memory info, shows threads, or sorts by memory use)
      The "h" option is problematic.  Standard BSD ps uses the option to print a header on each page of output, but older Linux ps uses the 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 and disable headers entirely, respectively.
      Terminals (ttys, or screens of text output) can be specified in several forms: /dev/ttyS1, ttyS1, S1. Obsolete "ps t" (your own terminal) and "ps t?" (processes without a terminal) syntax is supported, but modern options ("T", "-t" with list, "x", "t" with list) should be used instead.
      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, specify the other option (sorting or formatting) in some other way.
      For sorting, BSD "O" option syntax is O[+|-]k1[,[+|-]k2[,...]] Order the process listing according to the multilevel sort specified by the sequence of short keys from SORT KEYS, k1, k2, ... The `+' is quite optional, merely re-iterating the default direction on a key. `-' reverses direction only on the key it precedes. The O option must be the last option in a single command argument, but specifications in successive arguments are catenated.
      GNU sorting syntax is --sortX[+|-]key[,[+|-]key[,...]] Choose a multi-letter key from the SORT KEYS section. X may be any convenient separator character. To be GNU-ish use `='. The `+' is really optional since default direction is increasing numerical or lexicographic order. For example, ps jax --sort=uid,-ppid,+pid
      This ps works by reading the virtual files in /proc. This ps does not need to be suid kmem or have any privileges to run. Do not give this ps any special permissions.
      This ps needs access to a namelist file for proper WCHAN display. The namelist file must match the current Linux kernel exactly for correct output.
      To produce the WCHAN field, ps needs to read the System.map file created when the kernel is compiled. The search path is:
      $PS_SYSTEM_MAP
      /boot/System.map-`uname -r`
      /boot/System.map
      /lib/modules/`uname -r`/System.map
      /usr/src/linux/System.map
      /System.map
      Alternatively, on 2.5 kernels with KALLSYMS enabled, ps(1) can read the predecoded wchan value directly from /proc .
      The member used_math of task_struct is not shown, since crt0.s checks to see if math is present. This causes the math flag to be set for all processes, and so it is worthless. (Somebody fix libc or the kernel please.)
      Programs swapped out to disk will be shown without command line arguments, and unless the c option is given, in brackets.
      %CPU shows the cputime/realtime percentage. It will not add up to 100% unless you are lucky. It is time used divided by the time the process has been running.
      The SIZE and RSS fields don't count a task's page tables, process descriptor, kernel stack. This is at least ~10K of physical memory that is always resident. SIZE is the virtual size of the proc (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.
      "PROCESS FLAGS"
      FORKNOEXEC 1 forked but didn't exec
      SUPERPRIV 2 used super-user privileges
      DUMPCORE 4 dumped core

      "PROCESS STATE CODES"
      D uninterruptible sleep (usually IO)
      R runnable (on run queue)
      S sleeping
      T traced or stopped
      Z a defunct ("zombie") process

      For BSD formats and when the "stat" keyword is used, additional letters may be displayed:
      W has no resident pages
      < high-priority process
      N low-priority task
      L has pages locked into memory (for real-time and custom IO)

      "SORT KEYS"
      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. Pipe ps output into the sort(1) command if you want to sort the cooked values.
      lfCW lfCW l.
      KEY LONG DESCRIPTION
      .TH
      c cmd simple name of executable
      C cmdline full command line
      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
      K stime system 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 minor device number of tty
      T start_time time process was started
      U uid user ID number
      u user user name
      v vsize total VM size in bytes
      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"
      lfCW lfCW l.
      CODE NORMAL HEADER
      .TH
      %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"
      These may be used to control both output format and sorting.
      For example:  ps -eo pid,user,args --sort user
      lfCW lfCW.
      CODE HEADER
      .TH
      %cpu %CPU
      %mem %MEM
      alarm ALARM
      args COMMAND
      blocked BLOCKED
      bsdstart START
      bsdtime TIME
      c C
      caught CAUGHT
      cp CP
      cpu CPU
      cmd CMD
      comm COMMAND
      command COMMAND
      cputime TIME
      drs DRS
      dsiz DSIZ
      egid EGID
      egroup EGROUP
      eip EIP
      esp ESP
      etime ELAPSED
      euid EUID
      euser EUSER
      f F
      fgid FGID
      fgroup FGROUP
      flag F
      flags F
      fname COMMAND
      fsgid FSGID
      fsgroup FSGROUP
      fsuid FSUID
      fsuser FSUSER
      fuid FUID
      fuser FUSER
      gid GID
      group GROUP
      ignored IGNORED
      intpri PRI
      lim LIM
      longtname TTY
      lstart STARTED
      m_drs DRS
      m_trs TRS
      maj_flt MAJFL
      majflt MAJFLT
      min_flt MINFL
      minflt MINFLT
      ni NI
      nice NI
      nwchan WCHAN
      opri PRI
      pagein PAGEIN
      pcpu %CPU
      pending PENDING
      pgid PGID
      pgrp PGRP
      pid PID
      pmem %MEM
      policy POL
      ppid PPID
      pri PRI
      rgid RGID
      rgroup RGROUP
      rss RSS
      rssize RSS
      rsz RSZ
      rtprio RTPRIO
      ruid RUID
      ruser RUSER
      s S
      sess SESS
      session SESS
      sgi_p P
      sgi_rss RSS
      sgid SGID
      sgroup SGROUP
      sid SID
      sig PENDING
      sig_block BLOCKED
      sig_catch CATCHED
      sig_ignore IGNORED
      sig_pend SIGNAL
      sigcatch CAUGHT
      sigignore IGNORED
      sigmask BLOCKED
      stackp STACKP
      start STARTED
      start_stack STACKP
      start_time START
      stat STAT
      state S
      stime STIME
      suid SUID
      suser SUSER
      svgid SVGID
      svgroup SVGROUP
      svuid SVUID
      svuser SVUSER
      sz SZ
      time TIME
      timeout TMOUT
      tmout TMOUT
      tname TTY
      tpgid TPGID
      trs TRS
      trss TRSS
      tsiz TSIZ
      tt TT
      tty TT
      tty4 TTY
      tty8 TTY
      ucomm COMMAND
      uid UID
      uid_hack UID
      uname USER
      user USER
      vsize VSZ
      vsz VSZ
      wchan WCHAN

      "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
      CMD_ENV Set to one of posix,old,linux,bsd,sun,digital
      I_WANT_A_BROKEN_PS Force obsolete command line interpretation
      LC_TIME Date format
      PS_FORMAT Default output format override
      PS_SYSMAP Default namelist (System.map) location
      PS_SYSTEM_MAP Default namelist (System.map) location
      POSIXLY_CORRECT Don't find excuses to ignore bad "features"
      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 two exceptions are CMD_ENV (or PS_PERSONALITY), to set the desired default personality, and POSIXLY_CORRECT (or UNIX95), which should be set for Unix98 standard compliance.
      lfCW l.
      PS_PERSONALITY Description
      .TH
      none "Do the right thing"
      aix like AIX ps
      bsd like FreeBSD ps
      compaq like Digital Unix ps
      debian like the old Debian ps
      digital like Digital Unix ps
      gnu like the old Debian ps
      hp like HP-UX ps
      hpux like HP-UX ps
      irix like Irix ps
      linux deviate from Unix98 for convenience only
      old like the original Linux ps
      posix standard
      sco like SCO ps
      sgi like Irix ps
      sun like SunOS 4 ps
      sunos like SunOS 4 ps
      sysv standard
      unix standard
      unix95 standard
      unix98 standard

  • EXAMPLES

      To see every process on the system using standard syntax:
      ps -e
      To see every process on the system using BSD syntax:
      ps ax
      To see every process except those running as root (real & effective ID)
      ps -U root -u root -N
      To see every process with a user-defined format:
      ps -eo pid,tt,user,fname,tmout,f,wchan
      Odd display with AIX field descriptors:
      ps -o "%u : %U : %p : %a"
      Print only the process IDs of syslogd:
      ps -C syslogd -o pid=

  • SEE ALSO
  • STANDARDS
      This ps can be set to conform to version 2 of the Single Unix Specification.
  • AUTHOR
      ps(1) 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 <shields@msrl.com> 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 Mosberger-Tang wrote the generic BFD support for psupdate.
      Albert Cahalan <acahalan@cs.uml.edu> rewrote ps for full Unix98 and BSD support, along with some ugly hacks for obsolete and foreign syntax.
      The procps package is maintained by Robert Love and was created by Michael Johnson.
      Send bug reports to <procps-list@redhat.com>.
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