#!/bin/bash
#
# alice shell script
#
#   Enhanced version of alice script from _Learning_the_Bash_Shell_ (O'Reilly)
#   Demonstrates use of positional parameters ( $@ , $* , $1 , etc).
#   Invoke it with aruments, for example `alice in wonderland`
#
#
if [ -z "$1" ]        # if there were no parameters then ...
then
   echo "Usage: alice in wonderland"
   echo "  This script demonstrates the use of positional parameters in shell scripts."
   echo "  Invoke it with arguments, for example \`alice in wonderland\`, to see the use"
   echo '  of the variables $@ $* $0 $1 $2 $3 $4 $# and $IFS in shell scripting.'
   echo " "  
#
#
else                 
   echo "\$@: $@"    # $@ contains all of the positional parameters except $0 
   echo "\$*: $*"    # $* is like $@ except uses $IFS to seperate elements instead of just spaces 
   echo 'change $IFS with IFS=,'
   IFS=,                         # change $IFS to demonstrate difference beteen $@ and $*
   echo "\$@: $@"
   echo "\$*: $*"
#
   echo "\$0 \$1 \$2 \$3 \$4: $0 $1 $2 $3 $4"
   echo "\`basename \$0\` \$1 \$2 \$3 \$4: `basename $0` $1 $2 $3 $4"  
   echo "\${0##*/} \$1 \$2 \$3 \$4: ${0##*/} $1 $2 $3 $4" # ${0##*/} has similar effect to basename
   echo "\$# gives the number of arguments: $# "  # $# gives number of arguments passed to script
fi