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

twto.sh

#!/bin/sh
#
# Time a command with a timeout
#
# Author: Stephen Roberts <[email protected]>
# 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_NO_FP=66
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

TIMEOUT="$1"
shift
COMMAND="$*"
[ -z "$TIMEOUT" ] && usage && exit 0
[ -z "$COMMAND" ] && usage && exit 0

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

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

# Time the command
( ( time $COMMAND>/dev/null ) 2>"$output"; echo "done" >"$output" ) &
time_pid=$!

# Start timeout process
( sleep "$TIMEOUT" && echo timeout >"$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
    # Parse time command output
    mins=${line%m*}
    mins=${mins#real}
    secs=${line#*m}
    secs=${secs%s}

    # Attempt floating point arithmetic
    if command -v bc >/dev/null; then
      total=$(echo "$mins * 60 + $secs" | bc | xargs -I {} printf '%.3f' {})
    elif command -v perl >/dev/null; then
      total=$(perl -E "say $mins * 60 + $secs")
    else
      err "$EXIT_NO_FP" \
        "No command to handle floating point arithmetic found! Tried bd, perl."
    fi
    echo "$total"
  fi
done <"$output"