How do I display user ID associated with a process?

Transfered from Linux Config Disqus comments:


command which displays the user who invoked the command?


ps command will print any user ID associated with any process on the system. To see all processes currently running on a Linux system a “ps” command can be used. The most common options used by ps command are “aux”:

$ ps aux

The command above will display every process on the system and will include a following information:

    USER: effective user id of a process owner
    PID: associated process ID
    %CPU: CPU time utilization by a process
    %MEM: Memory ( RAM ) utilization by a process
    VSZ: virtual memory size of the process in KiB
    RSS: resident set size, the non-swapped physical memory that a task has used
    TTY: terminal associated with the process
    STAT: process state such as running or sleeping
    START: time when the command started
    TIME: cumulative CPU time
    COMMAND: the actual command that started this particular process

There may be many processes running on the system at any time. To narrow down our search we can output only processes associated with particular user:

$ ps -U root

To search for any particular process name we can combine ps command with grep:

$ ps aux | grep init
root     1  0.0  0.0   2876   668 ?    Ss   Feb25   0:02 /sbin/init

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