Bash script search, improve performance with large files Post: 303033044

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Top Forums Shell Programming and Scripting Bash script search, improve performance with large files Post 303033044 by SDohmen on Friday 29th of March 2019 04:53:59 AM

03-29-2019

Registered User

Quote:

Originally Posted by Peasant

When processing extremely large files you might consider using split first.
Then in multicore environments spawn several awks or greps to process it in parallel from shell script.
There are also GNU tools which offer parallelism without shell logic.

Should be a bit tougher to program, but processing time will be reduced significantly if you have cores and disks are fast to service.

Memory also comes in play, since split will read the files, and operating system will cache those files in memory, if the same is available.
Making those awks or greps processes much faster on read operations.

Of course, limit being free memory on the system and configuration of the file system caching in general.
In default configurations file system caching will be able to use a large portion free memory on most linux / unix systems i've seen.

Hope that helps
Regards
Peasant.

This sounds very interesting but there are 2 issues.

1. I have to split the files in smaller files (around 5k i guess) which isn't a big deal but a little bit annoying.
2. Since this is running in a script i have no idea how to call multiple instances of awk at the same time. Everything i know says that it handles each part of the script after each other and not at the same time. If you have an idea how to accomplish that please let me know since it does sound interesting/promising.

CPU and MEM arent the issue as they are sufficient. The only thing that can stall the script are the other scripts that are running also. I tried spreading them out as much as possible but some just take quite long to run and thats why i want to slim them down so they dont run together.

SDohmen

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LEARN ABOUT DEBIAN

pct-scanner-script

PCT-SCANNER-SCRIPT(1)					      General Commands Manual					     PCT-SCANNER-SCRIPT(1)

NAME

       pct-scanner-script - easy scan and create merged DjVu and PDF documents for archiving

SYNOPSIS

       pct-scanner-script [--help]

DESCRIPTION

       pct-scanner-script  is  a  bash script and configuration system to easily scan documents and create a digital archiving. It can create DjVu
       PDF and JPEG outputs, in merged and individual files. It also has a configuration system where different  configurations  can  be  defined,
       making it easy to switch between configurations.

       Please use pct-scanner-script --help to find all program options, the complete help, and all examples.

       Features:
	 - auto archiving in merged and individual DjVu, PDF, and JPEG files
	 - auto and manual resume when scanning somehow fails
	 - cascading configuration system, for easy customizing
	 - easy command-line-style bash program, with useful options
	 - archiving made possible with both adf and flatbed scanners
	 - built for productivity and daily use
	 - uses bash, scanadf and other mainstream processing tools
	 - multilanguage commandline output

OPTIONS

       -h, --help, -?
	      Show summary of options, help, and examples.

DEBUGGING

       This  program  is  a  helper  script  to easy scan and automated digital document archiving for normal and adf scanners. You can debug this
       script by running it as bash -x pct-scanner-script [options]. The script is just a nice wrapper for the scanadf, DjVu and PDF tools.

SEE ALSO

       scanadf(1),

AUTHOR

       pct-scanner-script and this manual page are written by:
	      Jelle de Jong <jelledejong@powercraft.nl>.

								  March 31, 2009					     PCT-SCANNER-SCRIPT(1)