alias mygrep='cat /path/to/logs/my.log | grep'

mygrep -i -E "WARN|java" |less

function mygrep () {
    args=$*
    grep "$args" /path/to/logs/my.log
}

grep "$args" /path/to/logs/my.log

function mygrep () {
    grep "$@" /path/to/logs/my.log
}