[CentOS] bash - safely pass untrusted strings?

[Jacques B.]

Here's a little script that I have to play around with positional
parameters.  I'm pretty certain I did not author this one but got it
either off the web or ina  book.  I added a line of comment in it but
I don't believe I made any other contributions to it.

Jacques B.

#!/bin/bash
# arglist.sh
# Invoke this script with several arguments, such as
# ./scriptname one "two three" four "five;six\" seven eight 'nine ten'


E_BADARGS=65

if [ ! -n "$1" ]
then
  echo "Usage: `basename $0` argument1 argument2 etc."
  exit $E_BADARGS
fi

echo

index=1          # Initialize count.

echo "Listing args with \"\$*\":"
for arg in "$*"  # Doesn't work properly if "$*" isn't quoted.
do
  echo "Arg #$index = $arg"
  let "index+=1"
done             # $* sees all arguments as single word.
echo "Entire arg list seen as single word."

echo

index=1          # Reset count.
                 # What happens if you forget to do this?

echo "Listing args with \"\$@\":"
for arg in "$@"
do
  echo "Arg #$index = $arg"
  let "index+=1"
done             # $@ sees arguments as separate words.
echo "Arg list seen as separate words."

echo

index=1          # Reset count.

echo "Listing args with \$* (unquoted):"
for arg in $*
do
  echo "Arg #$index = $arg"
  let "index+=1"
done             # Unquoted $* sees arguments as separate words.
echo "Arg list seen as separate words."

exit 0