mk/su-find-command.sh

   1 #!/bin/sh -
   2 #@ Find an executable command within a POSIX shell.
   3 #@ which(1) is not standardized, and command(1) -v may return non-executable,
   4 #@ so here is how it is possible to really find a usable executable file.
   5 #@ Use like this:
   6 #@    thecmd_testandset chown chown ||
   7 #@       PATH="/sbin:${PATH}" thecmd_set chown chown ||
   8 #@       PATH="/usr/sbin:${PATH}" thecmd_set_fail chown chown
   9 #@ or
  10 #@    thecmd_testandset_fail MAKE make
  11 #@ or
  12 #@    MAKE=/usr/bin/make thecmd_testandset_fail MAKE make
  13 #
  14 # 2017 - 2020 Steffen (Daode) Nurpmeso <steffen@sdaoden.eu>.
  15 # Thanks to Robert Elz (kre).
  16 # Public Domain
  17
  18 ## First of all, the actual functions need some environment:
  19
  20 if [ -z "${SU_FIND_COMMAND_INCLUSION}" ]; then
  21    VERBOSE=1
  22
  23    ( set -o noglob ) >/dev/null 2>&1 && noglob_shell=1 || unset noglob_shell
  24
  25    msg() {
  26       fmt=${1}
  27       shift
  28       printf >&2 -- "${fmt}\n" "${@}"
  29    }
  30 fi
  31
  32 ## The actual functions
  33
  34 acmd_test() { fc__acmd "${1}" 1 0 0; }
  35 acmd_test_fail() { fc__acmd "${1}" 1 1 0; }
  36 acmd_set() { fc__acmd "${2}" 0 0 0 "${1}"; }
  37 acmd_set_fail() { fc__acmd "${2}" 0 1 0 "${1}"; }
  38 acmd_testandset() { fc__acmd "${2}" 1 0 0 "${1}"; }
  39 acmd_testandset_fail() { fc__acmd "${2}" 1 1 0 "${1}"; }
  40 thecmd_set() { fc__acmd "${2}" 0 0 1 "${1}"; }
  41 thecmd_set_fail() { fc__acmd "${2}" 0 1 1 "${1}"; }
  42 thecmd_testandset() { fc__acmd "${2}" 1 0 1 "${1}"; }
  43 thecmd_testandset_fail() { fc__acmd "${2}" 1 1 1 "${1}"; }
  44
  45 ##  --  >8  - -  8<  --  ##
  46
  47 fc__pathsrch() { # pname=$1 exec=$2 varname=$3 verbok=$4
  48    fcps__pname=$1 fcps__exec=$2 fcps__varname=$3 fcps__verbok=$4
  49
  50    # It may be an absolute path, check that first
  51    if [ "${fcps__exec}" != "${fcps__exec#/}" ] &&
  52          [ -f "${fcps__exec}" ] && [ -x "${fcps__exec}" ]; then
  53       [ -n "${VERBOSE}" ] && [ ${fcps__verbok} -ne 0 ] &&
  54          msg ' . ${%s} ... %s' \
  55             "${fcps__pname}" "${fcps__exec}"
  56       [ -n "${fcps__varname}" ] &&
  57          eval "${fcps__varname}"="${fcps__exec}"
  58       return 0
  59    fi
  60
  61    # Manual search over $PATH
  62    fcps__oifs=${IFS} IFS=:
  63    [ -n "${noglob_shell}" ] && set -o noglob
  64    set -- ${PATH}
  65    [ -n "${noglob_shell}" ] && set +o noglob
  66    IFS=${fcps__oifs}
  67    for fcps__path
  68    do
  69       if [ -z "${fcps__path}" ] || [ "${fcps__path}" = . ]; then
  70          if [ -d "${PWD}" ]; then
  71             fcps__path=${PWD}
  72          else
  73             fcps__path=.
  74          fi
  75       fi
  76       if [ -f "${fcps__path}/${fcps__exec}" ] &&
  77             [ -x "${fcps__path}/${fcps__exec}" ]; then
  78          [ -n "${VERBOSE}" ] && [ ${fcps__verbok} -ne 0 ] &&
  79             msg ' . ${%s} ... %s' \
  80                "${fcps__pname}" "${fcps__path}/${fcps__exec}"
  81          [ -n "${fcps__varname}" ] &&
  82             eval "${fcps__varname}"="${fcps__path}/${fcps__exec}"
  83          return 0
  84       fi
  85    done
  86    return 1
  87 }
  88
  89 fc__acmd() {
  90    fca__pname=${1} fca__dotest=${2} fca__dofail=${3} \
  91       fca__verbok=${4} fca__varname=${5}
  92
  93    if [ "${fca__dotest}" -ne 0 ]; then
  94       eval fca__dotest=\$${fca__varname}
  95       if [ -n "${fca__dotest}" ]; then
  96          if fc__pathsrch "${fca__pname}" "${fca__dotest}" "${fca__varname}" \
  97                ${fca__verbok}; then
  98             return 0
  99          fi
 100          msg 'WARN: ignoring non-executable ${%s}=%s' \
 101             "${fca__pname}" "${fca__dotest}"
 102       fi
 103    fi
 104
 105    if fc__pathsrch "${fca__pname}" "${fca__pname}" "${fca__varname}" \
 106          ${fca__verbok}; then
 107       return 0
 108    fi
 109
 110    [ -n "${fca__varname}" ] && eval "${fca__varname}"=
 111    [ ${fca__dofail} -eq 0 ] && return 1
 112    msg 'ERROR: no trace of utility '"${fca__pname}"
 113    exit 1
 114 }
 115
 116 # s-sh-mode