List files
$ ack -f
List files according to pattern
$ ack -g <pattern>
Find a pattern in files
$ ack <pattern>
Find a word in files
$ ack -w <word>
Find a pattern in files but restrict the file format
$ ack [--python | --c | --yaml | --json | ..] <pattern>
Find the number of occurences of a pattern by file
$ ack -c <pattern>
Print the files that matches the expression
$ ack <pattern> -l
Print the files that doesn't match the expression
$ ack <pattern> -L