Home Accessibility Courses Twitter The Mouth Facebook Resources Site Map About Us Contact
For 2021 - online Python 3 training - see ((here)).

Our plans were to retire in summer 2020 and see the world, but Coronavirus has lead us into a lot of lockdown programming in Python 3 and PHP 7.
We can now offer tailored online training - small groups, real tutors - works really well for groups of 4 to 14 delegates. Anywhere in the world; course language English.

Please ask about private 'maintenance' training for Python 2, Tcl, Perl, PHP, Lua, etc.
File open, read, write test example
File Handling example from a Well House Consultants training course
More on File Handling [link]

This example is described in the following article(s):
   • Good, steady, simple example - Perl file handling - [link]

This example references the following resources:

Source code: fsv Module: P207
# File open, read, write test example

# Test that the output file won't clobber an old one
# And if that's OK open inputs and outputs

if (-e "file.file") {
        $sz = -s "file.file";
        $tm = -M "file.file";
        print STDERR "Size $sz b, updated $tm days ago\n";
        die "I'm not going to be that brutal\n";
open (FH,"../requests.xyz") or die "No input file\n";
open (FHO,">file.file") or die "Wrong - can't write\n";

# Copy lines including "Perl" to the screen and other lines
# to output file, counting the lines as you do so

$np = $nl = 0;
while ($lyne = <FH>) {
        if ($lyne =~ /Perl/) {
                print "PERL! $lyne";
        } else {
                print FHO $lyne;

# Close both files and report on the work done
# Note that report is supressed if STDOUT redirects to file

close FH;
close FHO;
-t STDOUT and print "Job Completed. Found $np out of $nl\n";

# Finally, provide user documentation through POD!


This example taught on Well House Consultants
Perl course - written for Delegates on October 2007.
See http://www.wellho.net/course/lpfull.html
graham@wellho.net / +44 (0) 1225 708225

=head1 Example of file handling in Perl

This example program shows the various elements of a
Perl program to tes, open, read and write files.

The file requests.xyz from the parent directory is
opened (if it exists) for input.

The file file.file in the current directory is
opened (if it does NOT exist) for output; if it
already exists, the program exits with an error
message after reporting critical status data.

Data is read line by line and copied from input
to output if it does NOT include the word "Perl";
if it does, the line is echoed to the screen.

Both files are closed, and if the output device
STDOUT is interactive (window rather that file) a
report line of the work done is added.


Learn about this subject
This module and example are covered on the following public courses:
 * Perl Programming
 * Perl bootcamp
 * Learning to program in Perl
 * Perl Programming
Also available on on site courses for larger groups

Books covering this topic
Yes. We have over 700 books in our library. Books covering Perl are listed here and when you've selected a relevant book we'll link you on to Amazon to order.

Other Examples
This example comes from our "File Handling" training module. You'll find a description of the topic and some other closely related examples on the "File Handling" module index page.

Full description of the source code
You can learn more about this example on the training courses listed on this page, on which you'll be given a full set of training notes.

Many other training modules are available for download (for limited use) from our download centre under an Open Training Notes License.

Other resources
• Our Solutions centre provides a number of longer technical articles.
• Our Opentalk forum archive provides a question and answer centre.
The Horse's mouth provides a daily tip or thought.
• Further resources are available via the resources centre.
• All of these resources can be searched through through our search engine
• And there's a global index here.

Web site author
This web site is written and maintained by Well House Consultants.

Purpose of this website
This is a sample program, class demonstration or answer from a training course. It's main purpose is to provide an after-course service to customers who have attended our public private or on site courses, but the examples are made generally available under conditions described below.

Conditions of use
Past attendees on our training courses are welcome to use individual examples in the course of their programming, but must check the examples they use to ensure that they are suitable for their job. Remember that some of our examples show you how not to do things - check in your notes. Well House Consultants take no responsibility for the suitability of these example programs to customer's needs.

This program is copyright Well House Consultants Ltd. You are forbidden from using it for running your own training courses without our prior written permission. See our page on courseware provision for more details.

Any of our images within this code may NOT be reused on a public URL without our prior permission. For Bona Fide personal use, we will often grant you permission provided that you provide a link back. Commercial use on a website will incur a license fee for each image used - details on request.

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2022: 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho

PAGE: http://www.wellho.net/resources/ex.php • PAGE BUILT: Sun Oct 11 14:50:09 2020 • BUILD SYSTEM: JelliaJamb