Inspect every process on the system.
Use the POSIX full format including UID, PID, PPID, start time, and command.
Which ps specification is correct?
ps -ef combines -e, which selects every process, with -f, which requests full-format columns such as UID and PPID.
Detailed explanation
psIncorrect. Plain ps generally shows only processes associated with the current terminal.
ps -efCorrect. -e selects all processes and -f displays the full format.
ps -p 1Incorrect. -p 1 selects only the process with PID 1.
ps -fIncorrect. -f changes the format but does not select all processes.
Try it yourself
An example you can run in a temporary verification environment.
ps -ef | head -n 1Expected result
UID、PID、PPID、C、STIME、TTY、TIME、CMD等の見出し（実装により表記差あり）Key points
- -e selects all processes
- -f requests full format
- Selection and display format are separate
Notes
- Environment: procps-ng 4.x
- Command output formatting can vary slightly by distribution or tool version.
- Run the example in a temporary directory or process when possible.
Foundation review
Read the scope first
Check whether the command acts on the current shell, a new process, an existing process, or a file.
Verify the observable result
Use the supplied command and compare the output with the expected result.