The -e argument specifies multiple patterns for matching:

    $ grep -e "pattern1" -e "pattern2"

This will print the lines that contain either of the patterns and output one line for each match. Consider this example:

    $ echo this is a line of text | grep -o -e "this" -e "line"
    this
    line

Multiple patterns can be defined in a file. The -f option will read the file and use the line-separated patterns:

    $ grep -f pattern_filesource_filename

Consider the following example:

    $ cat pat_file
    hello
    cool

    $ echo hello this is cool | grep -f pat_file
    hello this is cool