topic command "not found" exit code different when in an interactive shell in Operating System - Linux

command "not found" exit code different when in an interactive shell

Daavid Turnbull — Sun, 04 Feb 2007 21:36:48 GMT

I am trying to find a clean and simple way of determining if a command was "not found" (or if it was found having a non zero exit code).

Interactively I get:
__________________

> CheckEnvironment.sh
sh: CheckEnvironment.sh: not found
> echo $?
127
__________________

But performing similar logic from within a script I get (with set -x on):
___script________

CheckEnvironment.sh $0 $File
if [ $? -ne 0 ]
___output________
+ CheckEnvironment.sh ./start_RMS_services.sh.in /tmp/start_RMS_services.sh.in.1028238.errors
/tmp/start_RMS_services.sh.in.1028238.sh[23]: CheckEnvironment.sh: not found
+ [ 0 -ne 0 ]
__________________

So how can I tell if a command is "not found" within a script?

(Note: I am hoping to whereis or which etc.)

Re: command "not found" exit code different when in an interactive shell

Daavid Turnbull — Sun, 04 Feb 2007 21:43:04 GMT

Note should read:
(Note: I am hoping to avoid using whereis or which etc.)

Re: command "not found" exit code different when in an interactive shell

Steven Schweda — Sun, 04 Feb 2007 21:52:50 GMT

Which interactive shell?
Which shell for the script?

Re: command "not found" exit code different when in an interactive shell

Daavid Turnbull — Sun, 04 Feb 2007 23:05:20 GMT

Doh!!

I worked it out.

My issue was that I was creating the script as an inline file and had neglected to escape the $0... which was of course 0 at the point when the script was being produced... so this code always passed the test:
________
CheckEnvironment.sh ./start_RMS_services.sh.in /tmp/start_RMS_services.sh.in.938148.errors
if [ 0 -ne 0 ]
then
________

I shall close this thread now to avoid embarrassing replies ;-)

Re: command "not found" exit code different when in an interactive shell

Daavid Turnbull — Sun, 04 Feb 2007 23:07:22 GMT

See comments above

Re: command "not found" exit code different when in an interactive shell

Dennis Handly — Mon, 05 Feb 2007 22:40:12 GMT

For a real shell, there is a whence builtin. It returns no output but exit status of 1.

You may have to use "set +e" to turn off errexit when you do the whence in non-iteractive shells.