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Top Forums UNIX for Advanced & Expert Users File Processing: Handling spaces in a line Post 302874515 by Yoda on Friday 15th of November 2013 11:38:46 AM
Old 11-15-2013
Quote:
Originally Posted by baanprog
Iam doing below
Want to remove empty line
Want to remove lines that start with #
When trying to get the substring from the var also Iam having trouble. I dont want to read a line with such substrings.
I noticed that you are using way too many external commands when all of those tasks can be achieved using shell builtins.

Here is an example:
Code:
#!/bin/bash

while read line
do
        # Want to remove empty line
        [[ -z "$line" ]] && continue
        # Want to remove lines that start with #
        [[ "$line" =~ ^# ]] && continue
        # trying to get the substring
        subvar="${line:0:4}"
done < file

This User Gave Thanks to Yoda For This Post:
 

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EMPTY-PAGE(1)							 ExactImage Manual						     EMPTY-PAGE(1)

NAME
empty-page - empty page detector of the ExactImage toolkit SYNOPSIS
empty-page [option...] {-i | --input} input-file empty-page {-h | --help} DESCRIPTION
ExactImage is a fast C++ image processing library. Unlike many other library frameworks it allows operation in several color spaces and bit depths natively, resulting in low memory and computational requirements. empty-page counts dark pixels of a black and white image and decides with a threshold whether the page is most probably empty, and thus can be removed from the image processing stream. OPTIONS
-i file, --input file Read image from the specified file. -m n, --margin n Set width of border margin to skip. For speed reasons, the margin has to be a multiple of 8. The default is 16. -p x, --percentage x Set fraction of permissible dark pixels. The default is 0.05 (5%). -h, --help Display help text and exit. EXAMPLES
$ empty-page -i test.tif The image has 75461 dark pixels from a total of 1060992 (7.11231%). non-empty EXIT STATUS
The exit status is 0 if the image is mostly white, 1 otherwise. SEE ALSO
exactimage(7) AUTHORS
Jakub Wilk <jwilk@debian.org> Wrote this manual page for the Debian system. http://www.exactcode.de/site/open_source/exactimage/ This manual page incorporates texts found on the ExactImage homepage. COPYRIGHT
This manual page was written for the Debian system (and may be used by others). Permission is granted to copy, distribute and/or modify this document under the terms of the GNU General Public License, Version 2 or (at your option) any later version published by the Free Software Foundation. On Debian systems, the complete text of the GNU General Public License can be found in /usr/share/common-licenses/GPL-2. empty-page 09/09/2013 EMPTY-PAGE(1)
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