compare the dates of two files, return true (0) if file1 has been modified more recently otherwise 1

isnewer.bash

# compare the dates of two files, return true (0) if file1 has
# been modified more recently otherwise 1
# @param string file1
# @param string file2

function is_newer()
{   
    [ $# -ne 2 ] && return 1
    if [ ! -f $1 ] || [ ! -f $2 ]; then
        return 1       # No
    fi
    if [ -n "$(find $1 -newer $2 -print)" ]; then
        return 0       # Yes
    else
        return 1       # No
    fi
}