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Full Discussion: Bash script too slow
Top Forums Shell Programming and Scripting Bash script too slow Post 302390876 by tigta09 on Friday 29th of January 2010 09:52:10 AM
Old 01-29-2010
Bash script too slow

I have a bash script that will take approx. 130 days to complete. I am trying to grep a list of 1,144 user ID's out of 41 (1 GB each) files. The 41 files were originally one 41 G file, but that was horrendously too slow.Smilie
This is my current file:
Code:
#!/bin/bash
      for i in `cat WashFD.txt`  # 1,144 files
          do
           for b in `cat xfiles` # 41 "x??" files
            do
          echo "looking for " $i "in " $b
          cat $b | grep -i $i   >> SEID.searches
      done
    done

Currently, I am processing one of the 41 files every 4 minutes. 4 x 41 = 164 min.
164 / 60 (min/hour) = 2.73 hours per user_id. I have 1,144 user_id's multiplied by 2.73 = 3123.12 hours. 3123.12 / 24 (hours in a day) = 130.13 days.

As you can see, that is way too long to process this task. I don't know PERL but I've heard its faster. If anyone has any suggestions please let me know.Smilie

Last edited by vbe; 01-29-2010 at 10:54 AM.. Reason: code tags please
 

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BZEXE(1)						      General Commands Manual							  BZEXE(1)

NAME
bzexe - compress executable files in place SYNOPSIS
bzexe [ name ... ] DESCRIPTION
The bzexe utility allows you to compress executables in place and have them automatically uncompress and execute when you run them (at a penalty in performance). For example if you execute ``bzexe /bin/cat'' it will create the following two files: -r-xr-xr-x 1 root bin 9644 Feb 11 11:16 /bin/cat -r-xr-xr-x 1 bin bin 24576 Nov 23 13:21 /bin/cat~ /bin/cat~ is the original file and /bin/cat is the self-uncompressing executable file. You can remove /bin/cat~ once you are sure that /bin/cat works properly. This utility is most useful on systems with very small disks. OPTIONS
-d Decompress the given executables instead of compressing them. SEE ALSO
bzip2(1), znew(1), zmore(1), zcmp(1), zforce(1) CAVEATS
The compressed executable is a shell script. This may create some security holes. In particular, the compressed executable relies on the PATH environment variable to find gzip and some other utilities (tail, chmod, ln, sleep). BUGS
bzexe attempts to retain the original file attributes on the compressed executable, but you may have to fix them manually in some cases, using chmod or chown. BZEXE(1)
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