clipdel: Support getting pattern from standard input

clipdel

@@ -19,7 +19,8 @@ lock_timeout=2
 if [[ $1 == --help ]] || [[ $1 == -h ]]; then
     cat << 'EOF'
 clipdel deletes clipmenu entries matching a regex. By default, just lists what
-it would delete, pass -d to do it for real.
+it would delete, pass -d to do it for real. If no pattern is passed as an argument,
+it will try to read one from standard input.
 
 ".*" is special, it will just nuke the entire data directory, including the
 line caches and all other state.
@@ -44,7 +45,7 @@ fi
 
 # https://github.com/koalaman/shellcheck/issues/1141
 # shellcheck disable=SC2124
-raw_pattern=$1
+raw_pattern=${1:-$(cat)}
 esc_pattern=${raw_pattern/\#/'\#'}
 
 if ! [[ $raw_pattern ]]; then