update cutv

sh/cutv

@@ -4,14 +4,17 @@
 # NO_DASH
 
 cutv() { ### @-
-    [ $# -le 4 ] || { printf "%s\n" "$0: too many arguments" >&2; return 1; }
+    ### (WIP) create a short clip of a long video file.
+
+    argc -ge 2 "$0" "$@" || return
+    argc -le 4 "$0" "$@" || return
     local nel="${1?missing length parameter}"
     local f="${2?missing file parameter}"
     local g="cut."${${f##*/}%.*}".mp4"
     ffmpeg -hide_banner -i "$f" 2>&1 \
       | grep Duration \
       | grep -Eo '[0-9][0-9]:[0-9][0-9]:[0-9][0-9].[0-9][0-9]' | awk -F: '{print (($1*60+$2)*60+$3)+$4/100}' | read len
-    [[ "$len" -gt 0 ]] || return 1
+    [ "$len" -gt 0 ] || return 1
     echo "$g"
     ffmpeg \
       -hide_banner -loglevel warning -stats -stats_period 5 \