set -- *.ps

bash - test for no files matching *.foo

set -- *.ps
if [ -f "$1" ]
then
w3flag=$#
else
w3flag=0
fi

Bash file "if exist" and looping question - Questions

Linux tip: Bash test and comparison functions

Unix: Check if a file exists with certain prefix

shopt -s nullglob
x=(ABC*)
if [ -n "$x" ]; then
 echo foo
else
 echo bar
fi

For debugging or see what is going on in a script

set -xv # enable debugging