How to define a shell script with variable number of arguments?

Question

I would like to define a simple abbreviation of a call to gs (ghostscript) via a shell script. The first argument(s) give all the files that should be merged, t

Answer 1

To pass the output file as the last argument, use an array:

ARGS=("$@")
# Get the last argument
outputfile=${ARGS[-1]}
# Drop it from the array
unset ARGS[${#ARGS[@]}-1]

exec gs ... -sOUTPUTFILE=$outputfile "${ARGS[@]}"

Before version 4, bash didn't allow negative subscripts in arrays (and produced the error reported by Marius in the comments), so if you're using 3.x you need to use the much uglier

outputfile=${ARGS[${#ARGS[@]}-1]}

This works for bash 4.x as well.