HP-UX

What is this shell called ?

"/sbin/sh"

When I run "echo $SHELL" command on my HP-UX,I get above output.

In Linux It was "/bin/bash". Which is bash shell.

BASH and sh are both Bourne shells. BASH has extended features, like arrays and regular expressions, that /sbin/sh or /bin/sh can't be depended on to have. On Linux, /bin/sh is just a symlink to BASH, so it will, but will break if you move the script somewhere else.

If you use BASH features you should always give it #!/bin/bash

/bin/ksh, the Korn shell, is another extended Bourne shell that's more popular in the UNIX world rather than the Linux one, it also has arrays and a few other goodies (floating point numbers!) but its arrays don't work the same way as BASH's.

On Ubuntu and its derivatives /bin./sh is the DASH shell. DASH= Debian Almquist.

I have no knowledge also with that, I am glad you ask and got some answer from them. It's kinda benificial to have found this thread. Thank you.

/sbin/sh in HP-UX is the true bourne shell, it is different of /usr/bin/sh (Posix compliant shell) in the way it works and is normally used only by root, therefore it is not a good idea to change root's default shell by anything else (you can always call your preferred shell later...). I have seen engineers doomed after changing their root shell in /etc/passwd after having (not so) serious issues with servers not rebooting properly and so in single user (ah bad luck, /usr isnt mounted...). see:

Code:

ant:/home/vbe $ file /sbin/sh
/sbin/sh:       PA-RISC1.1 shared executable
ant:/home/vbe $ file /usr/bin/sh
/usr/bin/sh:    PA-RISC1.1 shared executable dynamically linked

Sorry vbe but this is wrong for HP-UX.
/sbin/sh is the Posix Shell not the old Bourne Shell. It's a version without dynamic libraries which will run standalone. System scripts will run with /sbin/sh or /bin/sh or /usr/bin/sh . The /sbin/sh version is faster but uses more memory per instance.


Try this modern Posix syntax:

Code:

a=1
b=2
c=$((a + b))
echo $c

See HP-UX "man sh" for an explanation of the various Shells. Just for interest, /usr/old/bin/sh is the old Bourne Shell.

Forgot to mention: The bash Shell is not supplied as standard with HP-UX.