program_path_check

#!/bin/bash
# inpath--Verifies that a specified program is either valid as is
# or can be found in the PATH directory list

in_path()
{
    # Given a command and the PATH, tries to find the command. Returns 0 if
    # found and executable; 1 if not. Note that this temporarily modifies
    # the IFS (internal field separator) but restores it upon completion.
    
    cmd=$1  ourpath=$2  result=1
    oldIFS=$IFS IFS=":"

    for directory in $ourpath
    do
    if [ -x $directory/$cmd ] ; then
        result=0 #If we're here, we found the command.
    fi
    done

    IFS=$oldIFS
    return $result
 }

checkForCmdInPath()
{
    var=$1

    if [ "$var" != "" ] ; then
        if [ "${var%${var#?}}" = "/" ] ; then #original if [ "${var:0:1}" = "/" ] ; then
            if [ !-x $var ] ; then
                return 1
            fi
        elif ! in_path $var "$PATH" ; then
        return 2
        fi
    fi
}

if [ $# -ne 1 ] ; then
    echo "Usage: $0 command" >&2 ; exit 1
fi

checkForCmdInPath "$1"
case $? in
    0 ) echo "$1 found in PATH"                   ;;
    1 ) echo "$1 not found or not executable"     ;;
    2 ) echo "$1 not found in PATH"               ;;
esac

exit 0