$_ variable in script does not work as expected

Question

I have c shell script that sources another:

source ./sc1.csh param

the script being sourced does the following:

set scriptName=($_)
if ( "$scriptName" == "" ) then
    set scriptName=$0
    echo "@**E: Please source this script, DO NOT RUN!"
    echo "ERROR"
    exit 1
else
    set scriptName=`basename $scriptName[2]`
endif

I expect $_ to contain "source ./sc1.csh param". However, it is actually empty. Manually running

source ./sc1.csh param

in the shell results in the correct, expected behavior. What's going on?

Thanks.

Answer 1

From man csh

$_

Substitutes the command line of the last command executed. (+)

As the script has not completed execution yet, then $_ hasn't been set.

What happens if you call the script again?