$cat out
if [ $# -eq 0 ]
    then
        echo "Usage: out [-v] filenames..." 1>&2
        exit 1
fi
if [ "$1" = "-v" ]
    then
        shift
        less -- "$@"
    else
        cat -- "$@"
fi

In out the -- arguments to cat and less tells these utilities that no more options follow on the command line and not to consider leading hyphen (-) in the following list as indicating options. Thus -- allows you to view a file with a name that starts with a hyphen… -- argument works with all Linux utilities that use the getopts builtin… This argument is particularly useful when used in conjunction with rm to remove a file whose name starts with a hyphen (rm -- -fname)…

A Practical Guide to Linux Commands, Editors and Shell Programming (p. 442)