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.
# 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
$ # 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 --
|%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|
|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|
|SZ||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
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 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.
- Task manager
- List of Unix programs
nmon— a system monitor tool for the AIX and Linux operating systems.
- The Single UNIX® Specification, Issue 7 from The Open Group – Commands & Utilities Reference,
- Show all running processes in Linux using ps command
- In Unix, what do the output fields of the ps command mean?