#!/bin/sh

# This script finds executable files on a Unix system by
# searching four sources of information: 
# (i) the user's PATH environment variable, 
# (ii) the 'whereis' command,
# (iii) a path supplied as a parameter and
# (iv) the 'locate' command (if available). 
#
# The result is a (space separated) list of directories where the 
# executable can be found.
# Please note that the returned list of directories is not 
# necessarily in the same order of directories found in the user's 
# PATH environment variable.  (This was done on purpose to reduce 
# disk i/o, see below.) 
# The primary advantage with this script is that the can collate
# search results from the various search tools provided by Unix. 
# The second advantage with this script is that duplicate paths
# are removed before accessing the disk, thereby reducing disk i/o. 
#
# Example invocation:
# findfile tclsh /local/tcl-7.5/bin:/roo/tcl-7.5/bin
# Here 'tclsh' is the executable file that we want to find and
# the second parameter is a colon-separated path of extra directories 
# to search. 
#
# Possible improvements:
# 1) use 'which' to check for aliases
# 2) use 'find' to search a hierarchy
# 3) include help page 
#
# Author: 	  Graham Phillips <graham@isi.edu>
# Date created:   1996 
# Last modified:  September 1999


findfile () {
# A function to search for executable files. 
# Argument 1: executable file that we want to find
# Argument 2: extra directories (not in PATH) to search 
# Example 
# findfile tclsh /local/tcl-7.5/bin:/roo/tcl-7.5/bin

   fname=$1
   if [ "$fname" = "" ] ; then
      exit
   fi
   found=0
   other_dirs=$2

   # First use `whereis`. 
   # Append results to f_list.
   # All our list contains entries separated by spaces.
   list=`whereis -b $fname 2>/dev/null`
   ff_list=`echo $list | sed 's/..*:[ ]*\(.*\)/\1/g'`
   f_list=""
   if [ "$ff_list" != "" ] ; then 
      for i in $ff_list ; do
         f_list="$f_list "`echo $i | sed 's/\(..*\)\/[^\/][^\/]*/\1/g'`
      done
   fi
  	
   # Next, try `locate`, which is typically found on FreeBSD systems.
   # This step can be time-consuming.
   paths=`which locate 2> /dev/null` 
   l_list=""
   if test -x $paths 2> /dev/null; then 
	l_list=`locate $fname 2> /dev/null`
	for i in $l_list ; do
		# check if the name after the last '/' is $fname
		# strip everything up to the last '/'
		j=`echo $i | sed 's/.*\///g'`
		if [ "$j" = "$fname" ]; then
			l_list="$l_list $j" 
		fi
 	done 
   fi

   # Next, use PATH environment variable and parameter passed in. 
   # Append results to u_list.
   paths="$f_list $l_list"`echo $PATH:$other_dirs | sed 's/\(:\)/ /g'`
   u_list=""
   for i in $paths ; do
      # remove trailing / in dir
      j=`echo $i | sed 's/\/$//g'`
      u_list="$u_list $j" 
   done
   
   # Next, sort and remove duplicates.
   # Results put in e_list.
   s_list=`echo $u_list | tr ' ' '\012' | sort | uniq`
   e_list=""
   for i in $s_list ; do
      if test -x ${i}/$fname ; then
        e_list="$e_list $i"
      fi
   done
   if [ "$e_list" != "" ] ; then
      echo $e_list 
   fi
}

findfile $*
exit