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#!/bin/bash



# Script to list:

#      directories (if called "lsd")

#      files       (if called "lsf")

#      links       (if called "lsl")

#  or  executables (if called "lsx")

# but not any other type of filesystem object.

# FIXME: add lsp   (list pipes)

#

# Usage:

#   <command_name> [switches valid for ls command] [dirname...]

#

# Works with names that includes spaces and that start with a hyphen.

#

# Created by Nick Clifton.

# Version 1.4

# Copyright (c) 2006, 2007 Red Hat.

#

# This is free software; you can redistribute it and/or modify it

# under the terms of the GNU General Public License as published

# by the Free Software Foundation; either version 3, or (at your

# option) any later version.



# It is distributed in the hope that it will be useful, but

# WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.



# ToDo:

#  Handle recursion, eg:  lsl -R

#  Handle switches that take arguments, eg --block-size

#  Handle --almost-all, --ignore-backups, --format and --ignore



main ()

{

  init

  

  parse_args ${1+"$@"}



  list_objects



  exit 0

}



report ()

{

  echo $prog": " ${1+"$@"}

}



fail ()

{

  report " Internal error: " ${1+"$@"}

  exit 1

}



# Initialise global variables.

init ()

{

  # Default to listing things in the current directory.

  dirs[0]=".";

  

  # num_dirs is the number of directories to be listed minus one.

  # This is because we are indexing the dirs[] array from zero.

  num_dirs=0;

  

  # Default to ignoring things that start with a period.

  no_dots=1

  

  # Note - the global variables 'type' and 'opts' are initialised in

  # parse_args function.

}



# Parse our command line

parse_args ()

{

  local no_more_args



  no_more_args=0 ;



  prog=`basename $0` ;



  # Decide if we are listing files or directories.

  case $prog in

    lsf | lsf.sh)

      type=f

      opts="";

      ;;

    lsd | lsd.sh)

      type=d

      # The -d switch to "ls" is presumed when listing directories.

      opts="-d";

      ;;

    lsl | lsl.sh)

      type=l

      # Use -d to prevent the listed links from being followed.

      opts="-d";

      ;;

    lsx | lsx.sh)

      type=f

      find_extras="-perm /111"

      ;;    

    *)

      fail "Unrecognised program name: '$prog', expected either 'lsd', 'lsf', 'lsl' or 'lsx'"

      ;;

  esac



  # Locate any additional command line switches for ls and accumulate them.

  # Likewise accumulate non-switches to the directories list.

  while [ $# -gt 0 ]

  do

    case "$1" in

      # FIXME: Handle switches that take arguments, eg --block-size

      # FIXME: Properly handle --almost-all, --ignore-backups, --format

      # FIXME:   and --ignore

      # FIXME: Properly handle --recursive

      -a | -A | --all | --almost-all)

        no_dots=0;

        ;;

      --version)

        report "version 1.2"

        exit 0

        ;;

      --help)

        case $type in

          d) report "a version of 'ls' that lists only directories" ;;

          l) report "a version of 'ls' that lists only links" ;;

          f) if [ "x$find_extras" = "x" ] ; then

               report "a version of 'ls' that lists only files" ;

             else

              report "a version of 'ls' that lists only executables";

             fi ;;

        esac

        exit 0

        ;;

      --)

        # A switch to say that all further items on the command line are

        # arguments and not switches.

        no_more_args=1 ;

        ;;

      -*)

        if [ "x$no_more_args" = "x1" ] ;

        then

          dirs[$num_dirs]="$1";

          let "num_dirs++"

        else

          # Check for a switch that just uses a single dash, not a double

          # dash.  This could actually be multiple switches combined into

          # one word, eg "lsd -alF".  In this case, scan for the -a switch.

          # XXX: FIXME: The use of =~ requires bash v3.0+.

          if [[ "x${1:1:1}" != "x-" && "x$1" =~ "x-.*a.*" ]] ;

          then

            no_dots=0;

          fi

          opts="$opts $1";

        fi

        ;;

      *)

        dirs[$num_dirs]="$1";

        let "num_dirs++"

        ;;

    esac

    shift

  done



  # Remember that we are counting from zero not one.

  if [ $num_dirs -gt 0 ] ;

  then

    let "num_dirs--"

  fi

}



list_things_in_dir ()

{

  local dir



  # Paranoia checks - the user should never encounter these.

  if test "x$1" = "x" ;

  then

    fail "list_things_in_dir called without an argument"

  fi



  if test "x$2" != "x" ;

  then

    fail "list_things_in_dir called with too many arguments"

  fi



  # Use quotes when accessing $dir in order to preserve

  # any spaces that might be in the directory name.

  dir="${dirs[$1]}";



  # Catch directory names that start with a dash - they

  # confuse pushd.

  if test "x${dir:0:1}" = "x-" ;

  then

    dir="./$dir"

  fi

  

  if [ -d "$dir" ]

  then

    if [ $num_dirs -gt 0 ]

    then

      echo "  $dir:"

    fi



    # Use pushd rather passing the directory name to find so that the

    # names that find passes on to xargs do not have any paths prepended.

    pushd "$dir" > /dev/null

    if [ $no_dots -ne 0 ] ; then

      find . -maxdepth 1 -type $type $find_extras -not -name ".*" -printf "%f\000" \

        | xargs --null --no-run-if-empty ls $opts -- ;

    else

      find . -maxdepth 1 -type $type $find_extras -printf "%f\000" \

        | xargs --null --no-run-if-empty ls $opts -- ;

    fi

    popd > /dev/null

  else

    report "directory '$dir' could not be found"

  fi

}



list_objects ()

{

  local i



  i=0;

  while [ $i -le $num_dirs ]

  do

    list_things_in_dir i

    let "i++"

  done

}



# Invoke main

main ${1+"$@"}