Issue
When using a *nix shell (usually bash), I often spawn a sub-shell with which I can take care of a small task (usually in another directory), then exit out of to resume the session of the parent shell.
Once in a while, I'll lose track of whether I'm running a nested shell, or in my top-level shell, and I'll accidentally spawn an additional sub-shell or exit out of the top-level shell by mistake.
Is there a simple way to determine whether I'm running in a nested shell? Or am I going about my problem (by spawning sub-shells) in a completely wrong way?
Solution
The $SHLVL variable tracks your shell nesting level:
$ echo $SHLVL
1
$ bash
$ echo $SHLVL
2
$ exit
$ echo $SHLVL
1
As an alternative to spawning sub-shells you could push and pop directories from the stack and stay in the same shell:
[root@localhost /old/dir]# pushd /new/dir
/new/dir /old/dir
[root@localhost /new/dir]# popd
/old/dir
[root@localhost /old/dir]#
Answered By - John Kugelman Answer Checked By - Senaida (WPSolving Volunteer)
