Question

I have the following script which works:

x=10
echo $x
now=$(date +'%Y-%m-%d')
echo $now

However, when I add a comment line at the beginning:

# comment
x=10
echo $x
now=$(date +'%Y-%m-%d')
echo $now

I get the following:

x=10: command not found
x: undefined variable

Why is the addition of the comment causing the script to fail?

if I do the following it works:

x=10
echo $x
now=$(date +'%Y-%m-%d')
# comment here
echo $now

Answer 1

This is a quirk of csh. (Stop using csh!) csh will process a script that does not begin with a ‘#’ using a “standard shell” (quoting from the csh manpage.) When the script begins with ‘#’, csh parses it. Your script is not valid csh.

You should probably add a shebang line to avoid this type of issue. That is, make the first line:

#!/bin/sh