Bash implementation of debianutils:which

which-min.sh

#!/usr/bin/env bash
IFS=:;if (($#>0))&&[ "${1:0:1}" == - ];then if [ "$1" != -a ];then printf >&2 'Illegal option %s\nUsage: which [-a] args\n' "$1";exit 2;else b=1;fi;shift;fi;read -rd '' -a g < <(printf %s:\\0 "$PATH");while (($# > 0));do f=0;for d in "${g[@]}";do e="$d/$1";while [[ -L $e && "$(ls -l "$e")" =~ -\>\ (.*) ]];do e="${BASH_REMATCH[1]}";done;if [[ -f $e && -x $e ]];then f=1;echo "$d/$1";((b))||break;fi;done;((f))||c=1;shift;done;exit $c

which.sh

#!/usr/bin/env bash
#
# @name
# which - locate a command
#
# @version
# 1.1.0
#
# @date
# 2019-05-28
#
# @author
# Léa Gris <lea.gris@noiraude.net>
#
# @license
# WTFPL http://www.wtfpl.net/
#
# @synopsis
# which [-a] filename ...
#
# @description
# Bash implementation of debianutils:which
# Behaves exactly like the native implementation
#
# @usage
# see https://manpages.debian.org/stretch/debianutils/which.1.en.html

function bash_which() {
  # locate a command
  local -i opt_a=0
  if (($# > 0)) && [[ ${1:0:1} == - ]]; then
    if [[ $1 != -a ]]; then
      printf >&2 'Illegal option %s\nUsage: which [-a] args\n' "$1"
      return 2
    else
      opt_a=1
    fi
    shift
  fi

  local IFS=:
  local -a path_arr
  read -rd '' -a path_arr < <(printf %s:\\0 "${PATH}")
  local -i rc=0
  while (($# > 0)); do
    local -i found=0
    local dir
    for dir in "${path_arr[@]}"; do
      local path="${dir}/${1}"
      while [[ -L ${path} && "$(ls -l "${path}")" =~ -\>[[:space:]](.*) ]]; do
        path="${BASH_REMATCH[1]}"
      done
      if [[ -f ${path} && -x ${path} ]]; then
        found=1
        echo "${dir}/${1}"
        ((opt_a)) || break
      fi
    done
    ((found)) || rc=1
    shift
  done
  return "${rc}"
}

bash_which "${@}"