On Sun, Jan 05, 2003 at 10:23:16PM +0200, Egor Tur wrote: > ps ax | grep lpd > 398 ? S 0:00 lpd Waiting > 5593 pts/13 S 0:00 grep lpd > ps ax | grep [l]pd > 398 ? S 0:00 lpd Waiting > > What do [l]?
Firstly, you want to quote '[l]pd', like so, in case you ever find yourself running it in a directory where there is a file called lpd. Secondly, there is no difference between what's matched by the regular expressions /lpd/ and /[l]pd/ (I'm using the slashes there in sed/awk/perl style to distinguish them more clearly from strings); both match the sequence of three characters 'l', 'p', and 'd'. (/[l]/ is a character class containing only the character 'l'; see 'man 7 regex'.) The only thing that /[l]pd/ does is ensure that the grep doesn't find the running grep command itself among the list of running processes output by 'ps ax'. The regular expression /[l]pd/ does not match the character string '[l]pd'. -- Colin Watson [[EMAIL PROTECTED]] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
