1

When I consecutively issue multiple commands which create a new shell, e.g.

zsh
screen
su user2
mc
sudo su
mc

Is there a command to show the “call stack”, i.e. a list of the commands which have not finished but created a new shell?

I might have issued some other commands among them, so the shell history won’t help. Moreover, I might have switched users and shells as shown in the above example.

I know I can find this information using the tree view in htop but can I get it directly using a command?

  • Those aren't subshells, but full processes. "Subshell" means a very particular thing re. the shell's environment, see e.g. Bash's manual – ilkkachu Feb 8 '18 at 13:12
  • @ilkkachu Thanks for your notice, I corrected my question. I was misled by the warning of the second mc instance: “Subshell support will be disabled.” – Melebius Feb 8 '18 at 13:25
5

You can use pstree (from PSmisc) for this:

pstree -s $$

The -s option shows the parents of the specified process identifier, and $$ is the current process’s identifier. pstree also shows the children of the specified process identifier, so you’ll end up with something along the lines of

systemd───systemd───gnome-terminal-───zsh───pstree

(with screen, sudo, su, mc etc. in your case).

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0

you can try

ps -t $(tty)

where

  • tty will return your current tty (I assume you are in interactive session).
  • $( tty) will bring output in command line.
  • ps -t will list all process related to the tty.

you can add ps flag you like. (e.g.)

ps -t $(tty) -o stime,etime,args
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  • Fun with tsort: ps -t $(tty) -oppid=,pid= | tsort | xargs -n1 ps -o pid=,comm= -p – Kusalananda Feb 8 '18 at 11:26

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