Shell script to time a command with a timeout (POSIX compliant)

twto.sh

#!/bin/sh
#
# Time a command with a timeout
#
# Author: Stephen Roberts <stephenroberts@gmail.com>
# Version: 1
#
# Usage: twto [OPTIONS] TIMEOUT COMMAND
#

# Disable globbing
set -f

usage() {
  printf "\nUsage: twto [OPTIONS] TIMEOUT COMMAND\n
Time a command with a timeout\n
Options:
  -s, --timeout-success  Exit 0 on timeout\n
Example: twto 60 ls\n"
}

err() {
  printf "\e[31m[ERROR]\t%s\e[0m\n" "$2" >&2
  exit "$1"
}

EXIT_NO_TIME=65
EXIT_TIMED_OUT=67

# Parse arguments
while [ $# -gt 0 ]; do
  case "$1" in
    -s|--timeout-success)
    EXIT_TIMED_OUT=0
    shift
    ;;
    *)
    POSITIONAL="$POSITIONAL $1"
    shift
    ;;
  esac
done
# shellcheck disable=SC2086
set -- $POSITIONAL

[ $# -lt 2 ] && usage && exit 0

TIMEOUT="$1"
shift
COMMAND="$*"

command -v /usr/bin/time >/dev/null || err "$EXIT_NO_TIME" \
  "Command not found: /usr/bin/time"

# Create a named pipe
output=$(mktemp -u)
mkfifo -m 600 "$output"

# Time the command
# shellcheck disable=SC2086
( (/usr/bin/time -p $COMMAND>/dev/null) 2>"$output"
  echo "done" >"$output" ) &
time_pid=$!

# Start timeout process
( trap 'kill -TERM $pid; exit 0' TERM
  sleep "$TIMEOUT" &
  pid=$!
  wait $pid
  echo timeout >"$output" ) &
sleep_pid=$!

# Trap exit to clean up
trap 'kill -0 "$time_pid" 1>/dev/null 2>&1'\
'  && kill "$time_pid"'\
'  && wait "$time_pid" 2>/dev/null;'\
'kill -0 "$sleep_pid" 1>/dev/null 2>&1'\
'  && kill "$sleep_pid"'\
'  && wait "$sleep_pid" 2>/dev/null;'\
'rm -f "$output"' EXIT

# Read from pipe until we see either "timeout" or "done"
while read -r line; do
  if [ "$line" = "done" ]; then
    exit 0
  elif [ "$line" = "timeout" ]; then
    echo "$TIMEOUT"
    err "$EXIT_TIMED_OUT" "timed out"
  elif test "${line#*real}" != "$line"; then
    # shellcheck disable=SC2086
    echo ${line#real}
    exit 0
  fi
done <"$output"