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Top Forums Shell Programming and Scripting BASH: Script jams Cygwin to 100% CPU - Post 302455045 by SilversleevesX on Monday 20th of September 2010 03:54:16 PM
Old 09-20-2010
BASH: Script jams Cygwin to 100% CPU -

I'd like to streamline the code more than a bit to get it to run faster.

There's a thread about this and related issues of mine on the Cygwin mailing-list, but I want to eliminate any chances it might just be inefficient/inelegant/crappy code. A previous run of the same script on both Cygwin and Ubuntu 9.04's GNOME Terminal, using a source file and a list file of equal length and content, had a significant difference in execution time (2m20s versus just under 3/4 of an hour, GNOME:Cygwin).

The code:
Code:
#!/bin/bash
SAVEIFS=$IFS
IFS=$(echo -en "\n\b")

while read 'line';
do
#8-point check:
	cate=$(exiv2 -g Iptc.Application2.Category -Pv $line)
	if [[ "$cate" == "" ]]; then cate2=" Category Tag";fi
	cred=$(exiv2 -g Iptc.Application2.Credit -Pv $line)
	if [[ "$cred" == "" ]]; then cred2=" Credit Tag";fi
	sour=$(exiv2 -g Iptc.Application2.Source -Pv $line)
	if [[ "$sour" == "" ]]; then sour2=" Source Tag";fi
	writ=$(exiv2 -g Iptc.Application2.Writer -Pv $line)
	if [[ "$writ" == "" ]]; then writ2=" Writer Tag";fi
	trans=$(exiv2 -g Iptc.Application2.TransmissionReference -Pv $line)
	if [[ "$trans" == "" ]]; then trans2=" Transmission Reference Tag";fi
	fixid=$(exiv2 -g Iptc.Application2.FixtureId -Pv $line)
	if [[ "$fixid" == "" ]]; then fixid2=" Event/Fixture Identifier Tag";fi
	objnm=$(exiv2 -g Iptc.Application2.ObjectName -Pv $line)
	if [[ "$objnm" == "" ]]; then objnm2=" Object Name Tag";fi
	locn=$(exiv2 -g Iptc.Application2.SubLocation -Pv $line)
	if [[ "$locn" == "" ]]; then locn2=" Location Tag";fi
echo -e "Evaluating File #$x \ $line."
iptc=$(echo $cate2$cred2$sour2$writ2$trans2$fixid2$objnm2$locn2)
case "$iptc" in 
 "" ) ;;
 * ) echo -e "$line:$iptc">>fieldsmissing.txt 
 y=$[y+1]
 ;;
esac
x=$[x+1]
unset cate2
unset cred2
unset sour2
unset writ2
unset trans2
unset fixid2
unset objnm2
unset iptc
done<list.txt
if [ "$y" -gt "0" ]; then
	echo -ne "\n$x JPEG files evaluated,\nwith $y missing some or all of 
their required IPTC tag data.\nFile-by-file is in fieldsmissing.txt.\n"
else 
	echo -ne "\n$x JPEG files evaluated, none missing any required IPTC
 tag data.\nNo new information was written to fieldsmissing.txt.\n"
fi
IFS=$SAVEIFS

I wouldn't pick on this script for any other reason than: since uninstalling one or two binaries from the Cygwin mirrors and from elsewhere, this is the only script (written by YT within the last two months ) that consistently raises CPU usage, as observed in Task Manager by me, to between 94 and 100% usage while it's being executed. Which is Cygwin "biting itself in the a**," to coin a phrase; the longer the cycle time the longer it takes for a script to finish.

Anyone's advice on how to streamline the code would be much appreciated.

BZT
 

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File::Spec::Cygwin(3pm) 				User Contributed Perl Documentation				   File::Spec::Cygwin(3pm)

NAME
File::Spec::Cygwin - methods for Cygwin file specs SYNOPSIS
require File::Spec::Cygwin; # Done internally by File::Spec if needed DESCRIPTION
See File::Spec and File::Spec::Unix. This package overrides the implementation of these methods, not the semantics. This module is still in beta. Cygwin-knowledgeable folks are invited to offer patches and suggestions. canonpath Any "" (backslashes) are converted to "/" (forward slashes), and then File::Spec::Unix canonpath() is called on the result. file_name_is_absolute True is returned if the file name begins with "drive_letter:", and if not, File::Spec::Unix file_name_is_absolute() is called. tmpdir (override) Returns a string representation of the first existing directory from the following list: $ENV{TMPDIR} /tmp $ENV{'TMP'} $ENV{'TEMP'} C:/temp Since Perl 5.8.0, if running under taint mode, and if the environment variables are tainted, they are not used. case_tolerant Override Unix. Cygwin case-tolerance depends on managed mount settings and as with MsWin32 on GetVolumeInformation() $ouFsFlags == FS_CASE_SENSITIVE, indicating the case significance when comparing file specifications. Default: 1 COPYRIGHT
Copyright (c) 2004,2007 by the Perl 5 Porters. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. perl v5.14.2 2010-09-20 File::Spec::Cygwin(3pm)
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