How to check if the current shell is where I logged in?

anupamsr · 02-13-2008, 07:55 AM

Hi!

Is there a way to check if the current shell is the one where I logged in? (I mean, gave my username and password?)

Dinithion · 02-13-2008, 08:57 AM

To get the PID of you running bash:
echo $$

Check if the current bash is loginshell:
ps aux | grep $$

If there is a dash in front of bash, its a loginshell, i.e:
xxx 11740 0.1 0.0 3800 2060 tty2 Ss 15:52 0:00 -bash (This is a loginshell)
xxx 11776 0.0 0.0 3516 1928 tty2 S 15:53 0:00 bash (This is childbash of a loginshell
xxx 11827 0.0 0.0 3496 1880 pts/1 Ss 15:54 0:00 bash (This is a VT in X)

anupamsr · 02-13-2008, 11:01 AM

Yes but that also lists the grep command!

anupamsr · 02-13-2008, 11:02 AM

Never mind!

ps x|grep $$|grep -v grep

anupamsr · 02-13-2008, 12:12 PM

Here, this does the trick:

Code:

if [ `ps o pid,args|grep -ce '^ *'$$' *-bash\( .*\)\?$'` -gt 0 ]; then
    echo login shell
fi

Adding this to .bashrc, now I can switch to zsh except when I want to run bash specifically.

There is still a problem, because many terminal emulators start with login shell. That I don't know how to handle, except by disabling this "feature".

And thanks a lot Dinithion!

Dinithion · 02-13-2008, 01:37 PM

A login shell (Where you enter username/password) is assigned a tty device. As you can see in my other post, the one at the bottom is a VT, and is assigned to pts/1, while the other two belongs to tty2. So you could always filter them out by adding tty to ps options.

anupamsr · 02-13-2008, 02:20 PM

Yes, but then the solution will not work if I ssh to another computer because then login shell is assigned a pts.

Since I am using rxvt-unicode, and starting the X server using startx from console, the current solution works nicely.

Dinithion · 02-13-2008, 03:15 PM

Oh yeah. I didn't think of that. As long as it works, its good