Is there a general command to see what shell is running?

Question

On some the shell can be read on in the command prompt, other can be seen when help is ran. But this are not covered by all the shells.

@StephaneChazelas You are right default is ambiguos I edited — Eduard Florinescu, May 15 '13 at 12:41

jlliagre · Accepted Answer · 2013-05-15T21:18:45.303

4

This should work with most shells and most OSes:

$ ps -o comm -p $$ | tail -n -1
ksh93

Edit: after reading the duplicate link, here is a simpler way that avoids the tail command.

$ ps -o comm= -p $$
ksh93

edited May 15 '13 at 21:18

answered May 15 '13 at 12:48

jlliagre

@jillagre Strange, the standard allows (and mentions) both syntaxes. So -n -1 and -n 1 are equivalent, while -n +1 is not. Bizarre. – l0b0 May 15 '13 at 13:40
I guess that's for historical reasons. Pre-standard tail didn't implemented the -n option, that was tail -1 for the last line and tail +1 for the first one. They kept the same syntax when -n was added not to break habits/usage. Not specifying a sign shouldn't but mean the last line(s), as the - in tail -1 was more to introduce an option than a sign indicator. – jlliagre May 15 '13 at 13:57

score 1 · Answer 2 · answered May 15 '13 at 12:10

1

You can see in /etc/passwd file, or type:

echo $SHELL

or

env

to see your default shell.

answered May 15 '13 at 12:10

cuonglm

Looking in /etc/passwd assumes that the user account exists in /etc/passwd, which may not be the case (for example in the case of such information being stored in LDAP, AD or other remote repositories). – user May 15 '13 at 13:07

2 Answers2