Asked by Chetan Joshi:
Question: What is the best way to find out what shell I am using on Linux? The echo $SHELL is not so reliable. Please let me know any tiny command or trick.
Answer: Chetan, echo $SHELL should work. However, here is old good UNIX trick. Use the command ps with -p {pid} option, which selects the processes whose process ID numbers appear in pid. Use the following command to find out what shell you are in:
ps -p $$
Sample outputs:
PID TTY TIME CMD 5217 ? 00:00:00 bash
So what is a $ argument passed to the -p option? Remember $ returns the PID (process identification number) of the current process, and the current process is your shell. So running a ps on that number displays a process status listing of your shell. In that listing, you will find the name of your shell (look for CMD column).
$ ps -p $$
Output:
PID TTY TIME CMD 6453 pts/0 00:00:00 csh
From my Linux box:
$ ps -p $$
Sample outputs:
PID TTY TIME CMD 5866 pts/0 00:00:00 bash
You can store your shell name in a variable as follows :
MYSHELL=`ps -hp $$|awk '{echo $5}'`
Please note those are backquotes, not apostrophes. Or better try out following if you have a bash shell:
MYSHELL=$(ps -hp $$|awk '{echo $5}')
Another option is as follows:
echo $0
OR
printf "%s\n" $0
Sample outputs from above commands:
33 comment
thanks this is what i looking for
you can also use
echo $0
This is the only method listed here that works for me (Mac OS X).
Thanks .. this was veryuse ful..echo $0
echo $0 – works for Raspberry Pi on Raspbian
-hp might not work. Also, echo?
ps h -p $$ | awk ‘{print $5}’
You can also find this out from et/passwd file :
Command to run:
# cat /etc/passwd
Sure, does this give accurate result?
No, it tells you the *default* shell for every user, not the one you are actually using in your current session.
Use
or as others said:
ps h p $$ | awk '{ print $NF }' /bin/bashIf you only need the shell name and not its executable full path:
basename $( ps h p $$ | awk '{ print $NF }' ) bashexactly what i was looking for. thanks
Thanks ..
you can also use
ps | grep $$
Thanks for this.
But the last sentence…
“Or better try out following if you have a bash shell:
MYSHELL=$(ps -hp $$|awk ‘{echo $5}’)
”
If you have a bash shell, couldn’t you just do
MYSHELL=”bash”
?
LOL, just what I was thinking. ^^
ps -p $$
and
echo $0
thanks a lot!
I noticed that, command such as; ps -$$, echo $SHELL, echo $0, printenv will print the current shell, but In case you have temperoraly changed your shell, these commands will not show the changes, unless you log out and log In. Whereas, cat /etc/passwd file will show the change mmediately without loging out.
For ex: At the current shell (ex-/bin/bash), if you type ‘chsh’ and then enter /bin/tcsh, it will change the shell to ‘tcsh’, but the cmds mentioned above will still be reporting the old shell that is /bin/bash, unless you logout. But, /et/passwd file will show the changes immediately.
Hi John,
and
always return the current shell, even from a sub-shell because they print the current process.
The /etc/passwd file is simply a file and then it does not store the current user shell but the login shell. In your example, you are using the Change login shell (chsh) to actually change the shell automatically launched at your login, and this is why the change is immediately visible in the /etc/passwd file.
I verified the output and it seems what you have said is totally opposite.. i.e, when u change the shell the changes are updated in ps -$$, echo $shell, echo $0 , and printenv. But not /etc/passwd file
you can also use
ps -u
$ bash
in
[[email protected] logs]$ uname -a
Linux wuvra99a0219 2.6.18-194.8.1.el5 #1 SMP Wed Jun 23 10:52:51 EDT 2010 x86_64 x86_64 x86_64 GNU/Linux
$SHELL is the only thing remaining as ksh:
[[email protected] logs]$ ps -$$
PID TTY STAT TIME COMMAND
18336 pts/13 S 0:00 bash
[[email protected] logs]$ echo $SHELL
/usr/bin/ksh
[[email protected] logs]$ echo $0
bash
pwd.
This is not 100% accurate.
Example (note how my shell is given the name “csh”, but it is really a tcsh):
So how to get the exact 100% accurate result?
How to know the current shell I’m using?
Nice tricks.
Hi, I have a problem which cannot be solved with the methods mentioned above. I need to find out within a bash script from which shell it was executed. If I use the methods above, I of course get always bash, since the executed script is a bash script. Does anybody have an idea?
Cheers, Jim
Just a note: why use awk if
ps -p $$ -o ucomm=
does the trick and supported by most *nixes?
Just a note: why use awk, if
ps -p $$ -o ucomm=
does the trick?
Which of the following command displays your login shell in Bash shell
a) $SHELL b) echo$ Bash c) echo$ 0 d) $0
Which of the following command displays your login shell in Bash shell
a)$ SHELL
b)echo $Bash
c)echo$) 0
d) $ 0
When `echo $SHELL` does work for you, try `echo $$ $SHELL`. Due to $$ representing the {pid} column it will append the pid to the output; include a space and it becomes, more, human readable.
Is this acceptable:
ps -p $$ > /dev/null; echo $0
Old question, but here is an answer. You need to get the current process’s parent id, and give that as the argument to ‘ps -p’. You can do it like this:
ps -p `ps -o ppid –no-headers -p $$`
If you want to convince yourself that you are getting the right answer, you can see the parent process id in a more human readable form with:
ps -O ppid $$
N.B. Lower case letter ‘o’ in the first command, upper case letter ‘O’ in the second one.
When I was learning the Unix shell using bash, I learned that you can just type in the name of the shell and the output will tell you. For example, when I type “bash” it prints out “bash-3.2” which tells that I am using the bash shell.