Shell Programming and Scripting

I have a script in TC shell, for some reason its not working.

I'm trying to kick off a script if there are any files in a particular directory "/sample/test3"

Can anyone point out the issue in the same

Code:

 
#!/usr/bin/tcsh
while true
do
    if ls /sample/test3 >& /dev/null  ; then /sample/app_code/run/initiateLoad.sh ; endif
    sleep 1800
done

The path /sample/test3 contains files so the if condition should have been successful and should have started the shell script, but its not happening.

And I have a requirement that the code has to be in tcsh.

tcsh is awesome as a shell, rubbish as a scripting language as the true/false logic is directly opposite to that of unix exit codes.

So a non-zero exit code, indicating failure in the command produces a non-zero value for csh (and tcsh) to interpret, which in c means "true". ie, yes means no and no means yes when evaluating command success like that.

Reverse your logic and you should be good to go.

Better yet, use bourne shell (/bin/sh) for that script - it's so simple, and bourne can be counted on the be everywhere.

This exact scenario is what finally convinced me to listen to reason and stop writing scripts in csh

All your code but the endif is bash (or zsh):

Code:

#!/bin/bash
while true
do
    if ls /sample/test3 >& /dev/null ; then /sample/app_code/run/initiateLoad.sh ; fi
    sleep 1800
done

Translated to tcsh (problematic and discouraged)

Code:

#!/usr/bin/tcsh
while (1)
    ls /sample/test3 >& /dev/null
    if ($status == 0) /sample/app_code/run/initiateLoad.sh
    sleep 1800
end