UNIX for Dummies Questions & Answers

It's 64-bit. When I use input redirect ( < ) on a smaller test file, I get no ouput. I do get the correct output when I omit the redirect symbol.

yes... 'look' doesn't do quite what I thought it did. When you give it no input file it tries to use something in /usr/share/dict!

So no, redirection won't work in this case.

Annoying that your version of look can't support large files on a 64-bit system! This may be a bug.

---------- Post updated at 01:53 PM ---------- Previous update was at 01:46 PM ----------

Looking at the code it doesn't have an explicit built-in limit, it just uses mmap. When I have access to a 64-bit machine later today I'll see what mmap does on 64-bit systems for enormous files.

Assuming your file is sorted and has some reasonablly high H value (the leading characters change) try some kind of a radix split to get small files.

For this example assume that most of the letters of the alphabet are found as the leading character of a record and they are all uppercase. This means you can have ~26 smaller files, all of which look will work on.

Code:

awk {file=substr($0,1,1); print $0 > file}' bigfile

This will create 26 smaller files all named A, B, C ... Z. So, now your command becomes:

Code:

string="String value"
look "$string"  ${string:0:1}

${string:0:1} evalautes to the first letter of the search string, which is the file name.

I tested the "look" command on a remote server through ssh. The machine has a Darwin Kernel Version 9.8.0 (32-bit). I'm getting the same error message. "File too large". Again, thank you for all the help.

Just did some testing at home. I don't think your Linux system is actually 64-bit; I just mmaped an entire 650-gigabyte file in 64-bit Linux. Granted that was a sparse file, so I went and mapped in all of /dev/sda next.

Even if you have a 64-bit processor, you get none of the benefits unless you install a 64-bit operating system -- namely, each process is limited to 4 gigabytes of virtual memory at most on a 32-bit system.

Naturally 32-bit OSX would have this limit too. Changing the OS without changing the number of bits won't give you more address space.

Try cat /proc/version

Result of cat /proc/version :

Linux version 2.6.35-28-generic (buildd@allspice) (gcc version 4.4.5 (Ubuntu/Linaro 4.4.4-14ubuntu5) ) #50-Ubuntu SMP Fri Mar 18 18:42:20 UTC 2011

I knew I needed a 64-bit system, so I installed the 64-bit version in advance.

When I try "uname -a", I get:
Linux patrick-G53JW 2.6.35-28-generic #50-Ubuntu SMP Fri Mar 18 18:42:20 UTC 2011 x86_64 GNU/Linux

Are there other issues that could have been overlooked thus far?

Then perhaps Ubuntu's saddled you with a 32-bit look for some reason. file /usr/bin/look