spinner - scripts - various script and utils
  HTML git clone git://z3bra.org/scripts
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       ---
       spinner (1225B)
       ---
            1 #!/bin/sh
            2 #
            3 # Display a spinner for as long as a lockfile is taken.
            4 # Take a lock with flock(1):
            5 #   flock /tmp/sleep.lock sleep 20 &
            6 #   spinner /tmp/sleep.lock
            7 
            8 # https://antofthy.gitlab.io/info/ascii/Spinners.txt
            9 randspin() {
           10         n=4
           11         c=${1:-$(seq $n|shuf|head -n1)}
           12         case $c in
           13         worm|1) echo "⠋ ⠙ ⠹ ⠸ ⢰ ⣰ ⣠ ⣄ ⣆ ⡆ ⠇ ⠏" ;;
           14         hole|2) echo "⣾ ⣽ ⣻ ⢿ ⡿ ⣟ ⣯ ⣷" ;;
           15         sand|3) echo "⠁ ⠂ ⠄ ⡀ ⡈ ⡐ ⡠ ⣀ ⣁ ⣂ ⣄ ⣌ ⣔ ⣤ ⣥ ⣦ ⣮ ⣶ ⣷ ⣿ ⡿ ⠿ ⢟ ⠟ ⡛ ⠛ ⠫ ⢋ ⠋ ⠍ ⡉ ⠉ ⠑ ⠡ ⢁" ;;
           16         leap|4) echo "⣀ ⢄ ⢂ ⢁ ⡈ ⡐ ⡠" ;;
           17         esac
           18 }
           19 
           20 usage() {
           21         echo "usage: $(basename $0) [-s spinner] [-p prefix] lockfile" >&2
           22 }
           23 
           24 spinner=$(randspin)
           25 while getopts "hp:s:" OPT; do
           26         case "$OPT" in
           27         s) spinner=$(randspin $OPTARG);;
           28         p) prefix="$OPTARG";;
           29         h) usage; exit 0;;
           30         *) usage; exit 1;;
           31         esac
           32 done
           33 shift $((OPTIND - 1))
           34 
           35 if [ $# -ne 1 ]; then
           36         usage
           37         exit 1
           38 fi
           39 
           40 # Exit immediately if lockfile doesn't exists
           41 [ -e "$1" ] || exit
           42 
           43 printf '%s[?25l  ' "$prefix"
           44 trap "printf '[?25h\b🗸\n'; exit" EXIT INT
           45 until flock -n "$1" true; do
           46         for c in $spinner; do
           47                 if flock -n "$1" true; then
           48                         exit 0
           49                 else
           50                         printf "\b%s" "$c"
           51                         sleep 0.08
           52                 fi
           53         done
           54 done