Bashscripts.org

I know it's a very silly question but could someone please explain the difference between "/bin/bash" & "/bin/sh"

I was under the impression that both are same but following output on my Ubuntu 8.10 is making me raise my eyebrows.

The diffrence between shells is just what they're capable of doing.
Bash is newer and more extensive in functionality then sh.

Can't tell you the exact things that set them apart but the manpages might give you a hint.

Best regards
Fredrik Eriksson

If you use

#!/bin/bash

at the head of your script your going to make sure your running in the BASH shell.

If you use

#!/bin/sh

your going to use WHATEVER shell is linked to sh. This is "normally" bash in most distro's....... Ubuntu in their "infinate" wisdom, thinks that linking sh to /bin/dash (the dash shell) is the way to go. I never use dash myself, I've always used bash or ksh. Simply putting the correct shebang line at the top of your scripts will solve any issues with regards to what your script is going to run in.

You can modify your Ubuntu system's /bin/sh symlink to point to /bin/bash:

Thanks guys...I got my answer...so the conclusion is:

1. If am executing the shell script using absolute or relative path, then interpreter used would be the one mentioned as sha-bang header.
2. And if I am using "sh" to invoke the shell script, interpreter used would be the one linked with "/bin/sh"

Correct.

Just to add more info, 3rd way to execute a script is directly through the interpreter. For e.g. consider following python script

#cat /tmp/sha_python


I can execute it using:
#python /tmp/sha_python


The interesting thing to note that is if I add a sha-bang header to it. i.e.

#cat /tmp/sha_bang_python


and if I invoke it using a wrong interpreter say "perl" still the script would work:
#perl /tmp/sha_bang_python