How to tell which shell is running a script

sbaker · #1 (**permalink**) 10-23-2009

I've been searching for a while and haven't found this answer anywhere.

How can I tell which shell is running my script from within the script? For example, I have lots of older scripts that we are porting to a new Linux system. Many of the scripts start with ":" alone on a line, which I think long ago forced /bin/sh.

Is there a way to tell within the script what it's being interpreted by? I tried "ps", but that only shows the name of the script.

Thanks,

Sean.

jim mcnamara · #2 (**permalink**) 10-23-2009

Modern shells support the $SHELL variable.

Code:

echo $SHELL

sbaker · #3 (**permalink**) 10-23-2009

Quote:

Originally Posted by jim mcnamara

Modern shells support the $SHELL variable.

Code:

echo $SHELL

$SHELL only shows the shell set at login. So if I login, $SHELL = /bin/ksh. If I start a new /bin/sh from my /bin/ksh, $SHELL still = /bin/ksh.

Sean.

cfajohnson · #4 (**permalink**) 10-23-2009

Quote:

Originally Posted by jim mcnamara

Modern shells support the $SHELL variable.

Code:

echo $SHELL

That doesn't tell you what shell is currently running; it tells you your default shell, which may or may not be your login shell.

nck · #5 (**permalink**) 10-23-2009

I always thought that the : in the beginning of a script meant that whatever shell you are in is what the script would use.

I've always found it safer to always specify #!/bin/?shell? at the beginning to make sure.

cfajohnson · #6 (**permalink**) 10-23-2009

Quote:

Originally Posted by nck

I always thought that the : in the beginning of a script meant that whatever shell you are in is what the script would use.

I've always found it safer to always specify #!/bin/?shell? at the beginning to make sure.

I usually use a shebang only when on a system that doesn't have a POSIX shell in /bin/sh or when I need some feature not supported by the standard shell.

Scrutinizer · #7 (**permalink**) 10-23-2009

Code:

ps -p$$ | xargs -n1 | tail -1

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