#!/bin/bash
# pb.sh: phone book

# Written by Rick Boivie, and used with permission.
# Modifications by ABS Guide author.

MINARGS=1     #  Script needs at least one argument.
DATAFILE=./phonebook
              #  A data file in current working directory
              #+ named "phonebook" must exist.
PROGNAME=$0
E_NOARGS=70   #  No arguments error.

if [ $# -lt $MINARGS ]; then
      echo "Usage: "$PROGNAME" data-to-look-up"
      exit $E_NOARGS
fi


if [ $# -eq $MINARGS ]; then
      grep $1 "$DATAFILE"
      # 'grep' prints an error message if $DATAFILE not present.
else
      ( shift; "$PROGNAME" $* ) | grep $1
      # Script recursively calls itself.
fi

exit 0        #  Script exits here.
              #  Therefore, it's o.k. to put
              #+ un-hashmarked comments and data after this point.

# ------------------------------------------------------------------------
Sample "phonebook" datafile:

John Doe        1555 Main St., Baltimore, MD 21228          (410) 222-3333
Mary Moe        9899 Jones Blvd., Warren, NH 03787          (603) 898-3232
Richard Roe     856 E. 7th St., New York, NY 10009          (212) 333-4567
Sam Roe         956 E. 8th St., New York, NY 10009          (212) 444-5678
Zoe Zenobia     4481 N. Baker St., San Francisco, SF 94338  (415) 501-1631
# ------------------------------------------------------------------------

$bash pb.sh Roe
Richard Roe     856 E. 7th St., New York, NY 10009          (212) 333-4567
Sam Roe         956 E. 8th St., New York, NY 10009          (212) 444-5678

$bash pb.sh Roe Sam
Sam Roe         956 E. 8th St., New York, NY 10009          (212) 444-5678

#  When more than one argument is passed to this script,
#+ it prints *only* the line(s) containing all the arguments.