AIX

See the link count of 5. Check link count of and size of /usr/bin/ksh. Are they the same?

Hi Murphy.
I executed the following : ls -l /usr/bin/ksh and the result is this :

-r-xr-xr-x 5 bin bin 290006 Jul 18 2010 /usr/bin/ksh

So this matches the result from ls -l /usr/bin/sh.


I also did a diff /usr/bin/sh /usr/bin/ksh and got nothing. So can i safely confirm that the file usr/bin/sh is same as file /usr/bin/ksh? Therefore the default shell in my case is actually a Korn shell even though the command echo $SHELL output /bin/sh?

Thanks,
Prashant

It would appear that it is the Korn shell.

To be certain, what is the output of the following command?

Code:

echo ${.sh.version}

The Output of the command echo ${.sh.version} is :

sh: ${.sh.version}: 0403-011 The specified substitution is not valid for this command.


Thanks.

This expansion only works in ksh93 and it means that you are using a 1988-version of the Korn shell. You can verify this by switching to vi-style command line editing mode and then pressing "CTRL-V" in command mode:

Code:

# set -o vi
# <ESC>
# <CTRL>-V
# Version M-11/16/88f

This is the output of an AIX 5.2-shell and shows a 88 version, revision "f".

To partially answer your original question: a POSIX-compliant system (which AIX is) is required to have a POSIX-shell in /bin/sh. If this is a link to another shell or an original binary doesn't matter. The user just can rely on the fact that issuing "/bin/sh" on the commandline will invoke a POSIX-compliant shell somehow.

What the requirements for a POSIX compliant shell are is laid down in the POSIX standards papers, issued and developed by the IEEE. What that in detail means i don't (read: never wanted to) know as i took IBMs word for their implementation of the shell being POSIX compliant at face value, but you could easily find that out by reading the paper and cross-checking it with the ksh documentation.

I hope this helps.

bakunin

Thanks Bakunin. That was a great explanation.My orginal query has now been answered.