Using grep

pyr3

I'm trying to use grep to search through a IRC log. For example if I want to find all instances of 'The_Ultimate_Samurai', I would *think* to search for .*Samurai and use the command 'grep .*Samurai .irclog'. But that isn't working. I can get it to work if I use 'grep .\\*Samurai .irclog', so I think that the shell was capturing the '*' from me, but in figuring that out I found something odd. 'grep .Samurai .irclog' works the same as 'grep .\\*Samurai .irclog'. This shouldn't be right. ".Samurai" should only match for one preceeding character, and ".*Samurai" should mean from zero to infinity preceeding characters but they seem to operate the same. I'm having a hard time figuring this out. Anyone can help me here?

pyr3

Ok, I've found that it is only tcsh that steals my '*' from me. Bash doesn't. Also I have found that the '.' works correctly when it is enclosed by letters. For example, "grep The.Samurai .irclog" won't find anything, but "grep The.*Samurai .irclog" will find everything it should. Why does the '.' work differently when it is on the front of the expression?

thuh freak

i'm pretty sure that grep adds an implicit * on both ends of your expression. if you use the option '-w' (or maybe its '-W') it takes off those darned implicit asterisks.



also, for both shells, you can escape away your asterisk-losing problem.



grep mysearch*string*with*stars*in*themiddle

...becomes...

grep mysearch\\*string\\*with\\*stars\\*in\\*themiddle

...also, you can do quotes...

grep "mysearch*string*with*stars*in*themiddle"

...and single quotes...

grep 'mysearch*string*with*stars*in*themiddle'

...aaah, the magic of shells...