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Full Discussion: Efficient Text File Writing
Homework and Emergencies Homework & Coursework Questions Efficient Text File Writing Post 302631369 by bakunin on Friday 27th of April 2012 09:02:03 AM
Old 04-27-2012
Scrutinizer is correct, but as there are always several ways in Unix to do something, you could do it with the exec too, if you use ksh (note that this won't work in bash, because bash doesn't have the print command):

Code:
exec 3> /some/output/file   # open the file as I/O channel 3 and clear
                            # its contents if it already exists

print -u3 "some text"       # print some text to channel 3
print -u3 "something else"  # same
...

exec 3>&-                   # close I/O-channel 3

This way you won't have to take care of the first ">" and subsequent ">>" redirections (if you mistakenly use ">" it will clear the file) and you will not have to repeat the output files name over and over again.

You could even influence the content of your output file with some program logic in the script - something the here-document provides little support for. For instance, the following would not be possible with a here-doc:

Code:
exec 3> /some/output/file

print -u3 "first line"
print -u3 "second line"

if [ <some_criteria> ] ; then
     print -u3 "----Optional line------"
fi
print -u3 "third line"

exec 3>&-


In exchange for helping you I'd like to ask you to learn about I/O channels (file descriptors) and redirection in Unix and how to use these. You might want to read this thread as a starter.

I hope this helps.

bakunin
This User Gave Thanks to bakunin For This Post:
 

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MicroMason::ExecuteCache(3pm)				User Contributed Perl Documentation			     MicroMason::ExecuteCache(3pm)

NAME
Text::MicroMason::ExecuteCache - Use a Cache for Template Results SYNOPSIS
Instead of using this class directly, pass its name to be mixed in: use Text::MicroMason; my $mason = Text::MicroMason->new( -ExecuteCache ); Use the standard compile method to parse a template into a subroutine: my $subref = $mason->compile( text=>$template ); print $subref->( 'name'=>'Dave' ); The template does not have to be interpreted the second time because the results are cached: print $subref->( 'name'=>'Dave' ); # fast second time When run with different arguments, the template is re-interpreted and the results stored: print $subref->( 'name'=>'Bob' ); # first time for Bob print $subref->( 'name'=>'Bob' ); # fast second time for Bob DESCRIPTION
Caches the output of templates. Note that you should not use this feature if your template code interacts with any external state, such as making changes to an external data source or obtaining values that will change in the future. (However, you can still use the caching provided by Text::MicroMason::CompileCache.) Public Methods compile() Wraps each template that is compiled into a Perl subroutine in a memoizing closure. Supported Attributes execute_cache Defaults to an instance of Text::MicroMason::Cache::Simple. This module uses a simple cache interface that is widely supported: the only methods required are "get($key)" and "set($key, $value)". You can use the simple cache classes provided in the Text::MicroMason::Cache:: namespace, or select other caching modules on CPAN that support the interface described in Cache::Cache. SEE ALSO
For an overview of this templating framework, see Text::MicroMason. This is a mixin class intended for use with Text::MicroMason::Base. For distribution, installation, support, copyright and license information, see Text::MicroMason::Docs::ReadMe. perl v5.10.1 2007-01-29 MicroMason::ExecuteCache(3pm)
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