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#!/bin/sh
help() {
echo "loop - execute command in loop
USAGE:
loop [OPTION]... <COMMAND>
OPTIONS:
-n INTERVAL sleep for given INTERVAL time between loops
all arguments of \`sleep\` command are valid
-c COUNT maximum count of loops (default: 1000)
-s clear screen for every execution
-q quiet, redirect output to /dev/null
-h show this help message
ENVIRONMENT VARIABLES:
LOOP_INTERVAL set INTERVAL time
MAX_LOOP_COUNT set loop COUNT"
}
err() { printf 'loop: %s\n' "$@" >&2; exit 1; }
while getopts 'sc:n:qh' o; do case "$o" in
s) cflag=1 ;;
n) export LOOP_INTERVAL="$OPTARG" ;;
c) export MAX_LOOP_COUNT="$OPTARG" ;;
q) qflag=1 ;;
h) help; exit ;;
*) err "invalid option -- $OPTARG" ;;
esac done
shift $((OPTIND - 1))
[ "$#" -lt 1 ] && err "no COMMAND given"
cmds="$*"
max_count="${MAX_LOOP_COUNT:-1000}"
[ -n "$LOOP_INTERVAL" ] && cmds="$cmds; sleep '$LOOP_INTERVAL'"
[ "$cflag" = 1 ] && cmds="clear; $cmds"
[ "$qflag" = 1 ] && cmds="$cmds >/dev/null"
for count in $(seq "$max_count"); do
eval "$cmds" || break
done
[ "$count" -ge "$max_count" ] && err "reached max loop COUNT: $max_count"
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