BASH: Break line, read, break again, read again... Post: 302520151

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Top Forums Shell Programming and Scripting BASH: Break line, read, break again, read again... Post 302520151 by SilversleevesX on Friday 6th of May 2011 02:17:34 AM

05-06-2011

Registered User

BASH: Break line, read, break again, read again...

...when the lines use both a colon and commas to separate the parts you want read as information.

Quote:

example.jpg:QVC,honeywell-labs.com,COM,blah,blah,blah,so-on,so-on,and so-on

The first version of this script used cut and other non-Bash-builtins, frequently, which made it nice and zippy with little more than average processor load in GNOME Terminal but, predictably, slow as a sloth on Valium and heavy on the CPU in Cygwin.

Code:

while read 'line';
do
n=$(echo $line)
file=$(echo -ne $n | cut -d: -f1)
tags=$(echo -ne $n | cut -d: -f2)
cate=$(echo -ne $tags | cut -d, -f1)
cred=$(echo -ne $tags | cut -d, -f2)
sour=$(echo -ne $tags | cut -d, -f3)
writ=$(echo -ne $tags | cut -d, -f4)
trans=$(echo -ne $tags | cut -d, -f5)
fixid=$(echo -ne $tags | cut -d, -f6)
objnm=$(echo -ne $tags | cut -d, -f7)
locn=$(echo -ne $tags | cut -d, -f8)
fname=`basename "$file"`
echo -e "Working on file $fname now."

I decided I wanted it to work faster, whatever it was run in.

Recently, I came across a line -- you might call it a command 'pair' -- in another script

Code:

exec 5<foo.txt
while IFS="," read -u5

for which I got help either here or on LQ. I've applied it to other scripts, and I've seen, yet again, the difference in speed a builtin often makes over an external binary. All those scripts had something in common, however: the data they read in was separated by a single delimiter, a colon or a comma, but not one of the former and several of the latter, as in my example above.

Re-working it with as much as I can get my mind around in terms of the 'read' and 'exec' commands, with only the most modest looking about on coder/scripter bulletin-board sites etc., I still can't get it to split the data in the $tags variable.

It looks like my approach is all wrong. So what would be a more useful way to go about it, keeping in mind that I want to employ more (all, if possible) builtins and stay away from "/bin" externals.

BZT

SilversleevesX

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LEARN ABOUT DEBIAN

flvtool2

FLVTOOL2(1)						      General Commands Manual						       FLVTOOL2(1)

NAME

       flvtool2 - a manipulation tool for flash video files

SYNOPSIS

       flvtool2 [-ACDPUVaciklnoprstvx]...[-key:value]...in-path|stdin[out-path|stdout]

DESCRIPTION

       If out-path is omitted, in-path will be overwritten.  In-path can be a single file, or a directory. If in-path is a directory, out-path has
       to be likewise, or can be omitted. Directory recursion is controlled by the -r switch. You can use stdin and stdout  keywords  as  in-  and
       out-path for piping or redirecting.

       Chain commands like that: -UP (updates FLV file than prints out meta data)

COMMANDS

       -A     Adds tags from -t tags-file

       -C     Cuts file using -i inpoint and -o outpoint

       -D     Debugs file (writes a lot to stdout)

       -H     Helpscreen will be shown

       -P     Prints out meta data to stdout

       -U     Updates FLV with an onMetaTag event

SWITCHES

       -a     Collapse space between cut regions

       -c     Compatibility mode calculates some onMetaTag values differently

       -key:value
	      Key-value-pair for onMetaData tag (overwrites generated values)

       -i timestamp
	      Inpoint for cut command in miliseconds

       -k     Keyframe mode slides onCuePoint(navigation) tags added by the add command to nearest keyframe position

       -l     Logs FLV stream reading to stream.log in current directory

       -n     Number of tag to debug

       -o timestamp
	      Outpoint for cut command in miliseconds

       -p     Preserve mode only updates FLVs that have not been processed before

       -r     Recursion for directory processing

       -s     Simulation mode never writes FLV data to out-path

       -t path
	      Tagfile (MetaTags written in XML)

       -v     Verbose mode

       -x     XML mode instead of YAML mode

SEE ALSO

       /usr/share/doc/flvtool2/examples/tags.xml

       http://www.inlet-media.de/flvtool2

AUTHOR

       flvtool2 was written by Norman Timmler <norman.timmler@inlet-media.de>

       This manual page was written by Todd Troxell <ttroxell@debian.org>, for the Debian project (but may be used by others).

								  August 24, 2007						       FLVTOOL2(1)