using bzip gzip zip in bash

lang-bash
#!/bin/bash

# check if the user put a file name
if [ $# -gt 0 ]; then

    # check if the file is exist in the current directory
    if [ -f "$1" ]; then

        # check if the file is readable in the current directory
        if [ -r "$1" ]; then
            echo "File:$1"
            echo "$(wc -c <"$1")"

            # Note the following two lines
            comp=$(bzip2 -k $1)
            echo "$(wc -c <"$comp")"
        else
            echo "$1 is unreadable"
            exit
        fi
    else
        echo "$1 is not exist"
        exit
    fi
fi