The ps command displays information about processes. Normally, only those processes that are running with your effective user ID and are attached to a controlling terminal (see termio(7I)) are shown. Additional categories of processes can be added to the display using various options. In particular, the -a option allows you to include processes that are not owned by you (that do not have your user ID), and the -x option allows you to include processes without controlling terminals. When you specify both -a and -x, you get processes owned by anyone, with or without a controlling terminal. The -r option restricts the list of processes printed to running and runnable processes.
ps displays in tabular form the process ID, under PID; the controlling terminal (if any), under TT; the cpu time used by the process so far, including both user and system time, under TIME; the state of the process, under S; and finally, an indication of the COMMAND that is running.
The state is given by a single letter from the following:
Process is running on a processor.
Sleeping. Process is waiting for an event to complete.
Runnable. Process is on run queue.
Zombie state. Process terminated and parent not waiting.
Traced. Process stopped by a signal because parent is tracing it.
The following options must all be combined to form the first argument:
Includes information about processes owned by others.
Displays the command name rather than the command arguments.
Displays the environment as well as the arguments to the command.
Displays all processes. Without this option, ps only prints interesting processes. Processes are deemed to be uninteresting if they are process group leaders. This normally eliminates top-level command interpreters and processes waiting for users to login on free terminals.
Displays a long listing, with fields F, PPID, CP, PRI, NI, SZ, RSS, and WCHAN as described below.
Produces numerical output for some fields. In a user listing, the USER field is replaced by a UID field.
Restricts output to running and runnable processes.
Displays accumulated CPU time used by this process and all of its reaped children.
Lists only process data associated with the terminal, term. Terminal identifiers may be specified in one of two forms: the device's file name (for example, tty04 or term/14 ) or, if the device's file name starts with tty, just the digit identifier (for example, 04).
Displays user-oriented output. This includes fields USER, %CPU, %MEM, SZ, RSS, and START as described below.
Obsolete. This option no longer has any effect. It causes ps to exit without printing the process listing.
Displays a version of the output containing virtual memory. This includes fields SIZE, %CPU, %MEM, and RSS, described below.
Uses a wide output format (132 columns rather than 80). If the option letter is repeated, that is, -ww, uses arbitrarily wide output. This information is used to decide how much of long commands to print.
Includes processes with no controlling terminal.
A process number may be given, in which case the output is restricted to that process. This option must be supplied last.
Fields that are not common to all output formats:
Name of the owner of the process.
CPU use of the process. This is a decaying average over up to a minute of previous (real) time.
The total size of the process in virtual memory, including all mapped files and devices, in kilobyte units.
Same as SIZE.
Real memory (resident set) size of the process, in kilobyte units.
Numerical user-ID of process owner.
Numerical ID of parent of process.
Short-term CPU utilization factor (used in scheduling).
The priority of the process (higher numbers mean lower priority).
The starting time of the process, given in hours, minutes, and seconds. A process begun more than 24 hours before the ps inquiry is executed is given in months and days.
The address of an event for which the process is sleeping (if blank, the process is running).
The ratio of the process's resident set size to the physical memory on the machine, expressed as a percentage.
Flags (hexadecimal and additive) associated with the process. These flags are available for historical purposes; no meaning should be currently ascribed to them.
A process that has exited and has a parent, but has not yet been waited for by the parent, is marked <defunct> ; otherwise, ps tries to determine the command name and arguments given when the process was created by examining the user block.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
Things can change while ps is running. The picture ps gives is only a close approximation to the current state. Some data printed for defunct processes is irrelevant.