Bsrgvty

I'm running the sleep command in terminal using screen and in detached mode.

Once the screen immediately returns, I'm running ps command to verify the sleep is running.

$ screen -d -m 'sleep 2m'
[raj@localhost ~]$ ps
PID TTY TIME CMD
22795 pts/0 00:00:00 bash
22869 pts/0 00:00:00 ps

But the command didn't show sleep. What is that I'm doing wrong here?

This was confusing to me initially as well. I then re-read the local screen man page for the SYNOPSIS -- the online man page does not give a synopsis) -- and noticed that it said:

screen [ -options ] [ cmd [ args ] ]

... which led me to believe that it wanted to see the cmd and args as independent arguments.

Since you gave that first argument as a quoted value -- 'sleep 2m' -- it tried to execute a command named (exactly) 'sleep 2m', as opposed to what you really wanted, which was sleep with its own argument of 2m. The screen command exited successfully (in my testing), but it did not successfully execute your command.

Use, instead:

screen -d -m sleep 2m

Instead of ps, which will only show processes associated with the current terminal (of which the SCREEN and related processes are not), use:

ps x

which will show it:

$ ps x
 PID TTY STAT TIME COMMAND
 # ...
 7514 pts/1 Ss 0:00 -bash
 7761 ? Ss 0:00 SCREEN -d -m sleep 2m
 7762 pts/2 Ss+ 0:00 sleep 2m
 7880 pts/1 R+ 0:00 ps x
 # ...

Would using nohup suffice? It will show in ps where as running it in screen may make the process hidden within the screen process.

An example of this would be from bash..

nohup your-command &

If you want to exit this terminal session you may want to use an at job command..

at now + 1 minute

nohup your-command &

(ctrl-d)