![]() The ps command | |
Original author(s) | AT&T Bell Laboratories |
---|---|
Developer(s) | Various open-source and commercial developers |
Initial release | February 1973 |
Written in | C |
Operating system | Unix, Unix-like, Plan 9, Inferno, KolibriOS, IBM i |
Platform | Cross-platform |
Type | Command |
License | Plan 9: MIT License |
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
[edit]KolibriOS includes an implementation of the ps
command.[1] The ps command has also been ported to the IBM i operating system.[2] In Windows PowerShell, ps
is a predefined command alias for the Get-Process
cmdlet, which essentially serves the same purpose.
Examples
[edit]# 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
[edit]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
[edit]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.
See also
[edit]- Task manager
- kill (command)
- List of Unix commands
- nmon – a system monitor tool for AIX and Linux operating systems
- pstree (Unix)
- lsof
References
[edit]- ^ "Shell - KolibriOS wiki".
- ^ IBM. "IBM System i Version 7.2 Programming Qshell" (PDF). IBM. Retrieved 2020-09-05.
Further reading
[edit]- McElhearn, Kirk (2006). The Mac OS X Command Line: Unix Under the Hood. John Wiley & Sons. ISBN 978-0470113851.
- Shotts (Jr), William E. (2012). The Linux Command Line: A Complete Introduction. No Starch Press. pp. 96–98. ISBN 9781593273897. Retrieved 16 October 2017.
External links
[edit]- The Single UNIX Specification, Version 4 from The Open Group – Shell and Utilities Reference,
- Plan 9 Programmer's Manual, Volume 1 –
- Inferno General commands Manual –
- Show all running processes in Linux using ps command
- In Unix, what do the output fields of the ps command mean?