ps (Unix)

In most Unix-like operating systems, the ps program (short for "process status") displays the currently-running processes. A related Unix utility named top provides a real-time view of the running processes.

In Windows PowerShell, ps is a predefined command alias for the Get-Process cmdlet which essentially serves the same purpose.

Examples

For example:

# ps
  PID TTY          TIME CMD
 7431 pts/0    00:00:00 su
 7434 pts/0    00:00:00 bash
18585 pts/0    00:00:00 ps

Users can also utilize the ps command in conjunction with the grep (see the pgrep and pkill commands) command to find information about one process, such as its process id:

$ # Trying to find the PID of `firefox-bin` which is 2701
$ ps -A | grep firefox-bin
2701 ?        22:16:04 firefox-bin

and the easier version with pgrep:

$ pgrep -l firefox-bin
2701 firefox-bin

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

# ps -U root -u root u
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  10348   640 ?        Ss    2009   0:06 init [5]

Options

ps has many options. On operating systems that support the SUS and POSIX standards, ps commonly runs with the options -ef, where "-e" selects every process and "-f" chooses the "full" output format. Another common option on these systems is -l, which specifies the "long" output format.

Most systems derived from BSD fail to accept the SUS and POSIX standard options because of historical conflicts (for example, the "e" or "-e" option will cause the display of environment variables). On such systems, ps commonly runs with the non-standard options aux, where "a" lists all processes on a terminal, including those of other users, "x" lists all processes without controlling terminals and "u" adds a column for the controlling user for each process. Note that, for maximum compatibility when using this syntax, there is no "-" in front of the "aux". Also you can add 'ww' after aux, like "ps auxww" for complete information about the process including all parameters.

See also

• Task manager
• kill
• List of Unix programs
• nmon — a system monitor tool for the AIX and Linux operating systems.
• pgrep
• pstree
• top

External links

• ps — Specification from the Single Unix Specification
• Show all running processes in Linux using ps command
• ps(1): report a snapshot of the current processes – Linux User Commands Manual