Ps (Unix)

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

Implementations KolibriOS includes an implementation of the command. The command has also been ported to the IBM i operating system. In Windows PowerShell, ps is a predefined command alias for the Get-Process cmdlet, which essentially serves the same purpose.

Examples # 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 pipeline ps with other commands, such as less to view the process status output one page at a time:

$ ps -A | less

Users can also utilize the ps command in conjunction with the grep command (see the pgrep and pkill commands) to find information about a single process, such as its id:$ # Trying to find the PID of `firefox-bin` which is 2701 $ ps -A | grep firefox-bin 2701 ? 22:16:04 firefox-bin

The use of pgrep simplifies the syntax and avoids potential race conditions: $ pgrep -l firefox-bin 2701 firefox-bin

To see every process running as root in user format: # ps -U root -u USER PID %CPU %MEM VSZ RSS TT STAT STARTED TIME COMMAND root 1 0.0 0.0 9436 128 - ILs Sun00AM 0:00.12 /sbin/init --

Header line Column Header Contents %CPU How much of the CPU the process is using %MEM How much memory the process is using ADDR Memory address of the process C or CP CPU usage and scheduling information COMMAND* Name of the process, including arguments, if any NI nice value F Flags PID Process ID number PPID ID number of the process's parent process PRI Priority of the process RSS Resident set size S or STAT Process status code START or STIME Time when the process started VSZ Virtual memory usage TIME The amount of CPU time used by the process TT or TTY Terminal associated with the process UID or USER Username of the process's owner WCHAN Memory address of the event the process is waiting for * = Often abbreviated

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 from X/Open System Interfaces (XSI), an optional extension to POSIX.

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 display 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. For maximum compatibility, there is no "-" in front of the "aux". "ps auxww" provides complete information about the process, including all parameters.

See also Task manager kill (command) List of Unix commands nmon – a system monitor tool for AIX and Linux operating systems pstree (Unix) lsof

References

Ps (Unix)

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