UNIX for Dummies Questions & Answers

I am trying to find lines in a text file larger than 3 Gb that start with a given string. My command looks like this:

$ look "string" "/home/patrick/filename.txt"


However, this gives me the following message:

"look: /home/patrick/filename.txt: File too large"


So, I have two questions.
1. How can I make this work with the "look" command and not any other commands such as "grep"?
2. If I were to use "grep", would it take longer than using "look", provided that I can somehow get "look" to work on this large file.

Thanks!

What system are you on?

Sometimes you can get around this by having the shell open the file for it. Redirect it in instead of giving it the filename.

Code:

look string < giganticfile

This trick doesn't work for things which need to know how big the file is, but look doesn't strike me as one of them.

Thanks for the response. I'm using Ubuntu 10.10.
Trying out your suggestion from a shell, I am no longer getting a error message but I'm also not getting any output either. Do you have an idea why?

Ah, I think I see:

Code:

DESCRIPTION
     The look utility displays any lines in file which contain string as a
     prefix.  As look performs a binary search, the lines in file must be
     sorted (where sort(1) got the same options -d and/or -f that look is
     invoked with).

...so look really does need to know how long the file is.

grep should work since it doesn't, but won't have the performance advantage of being able to do a binary search.

Code:

grep '^string to find' bigfile

will find words just like look does. Minus the good performance.

Yes, the boost in performance is precisely why I need "look". hm..

Is your operating system 32-bit or 64-bit? The 64-bit version may not have the file size limit.