#!/bin/sh
#
# Lookup ports.
#
# Copyright (c) 2006 Lorance Stinson LoranceStinson AT gmail DOT com

#**************************************************************************
# Defaults.
#**************************************************************************
SERVICES="/etc/services" # The file with ports.
PROTOCOL="(udp|tcp)" # The default protocol search.

#**************************************************************************
# usage() - Display the command line help text.
#**************************************************************************
usage(){
    if [ "$1" ] ; then
        echo "$1"
        echo ""
    fi
    cat<<EOHELP
Usage:  `basename $0` [options] <port|service>
Lookup a port or service in the file $SERVICES and print it's use.
By default both TCP and UDP ports are retrieved.
Options:
    -f <file>   Use an alternate ports file.
    -h          This text.
    -t          Only list the TCP use.
    -u          Only list the UDP use.
EOHELP
    exit 1
}

#**************************************************************************
# Check and handle commandline options.
#**************************************************************************
while [ "$#" -gt 0 ] ; do
    case "$1" in
        # Alternate services file.
        -f) [ "$2" ] && SERVICES="$2" || usage "$1 requires an argument."
            shift 2;;
        # Print the help text.
        -h) usage;;
        # List only TCP.
        -t) PROTOCOL="tcp"; shift;;
        # List only UDP.
        -u) PROTOCOL="udp"; shift;;
        # End of options
        --) [ "$2" ] && SEARCH="$2"; break;;
        -*) usage "Invalid option $1";;
        # Anything else should be the search string.
        *)  SEARCH="$1"; shift;;
    esac
done

[ "$SEARCH" ] || usage "Specify a port to lookup."

# Perform the search.
if [ "`expr "$SEARCH" : '[0-9]*$'`" -ne 0 ] ; then
    egrep "[^0-9]$SEARCH/$PROTOCOL" $SERVICES
else
    egrep "^.*$SEARCH.*[ 	]*[0-9]*/$PROTOCOL" $SERVICES
fi