Exercises, examples and other material relating to training module P215. This topic is presented on public course Perl for Larger Projects

You can do much more with files in Perl than just read or write text from and to them. This module covers checking on file size and status, checking all the files in a directory, handling binary data and more. It also covers file system management functions that let you create and delete files and directories, and change permissions on them.

Solution Centre - all article listing
Solution Centre - all article listing
Writing to and reading from files

Articles and tips on this subject		updated
3839	Spraying data from one incoming to series of outgoing files in Perl Scenario. I have a lot of data that contains large numbers of records which I want to separate into groups. For example, an incomeing web server log file which I want to split out and process visitor by visitor. Using Perl, I can loop through my data line by line and store it into a hash - for example:     while ($lyne ...	2012-08-18
3412	Handling binary data in Perl is easy! Perl can handle binary data just as easily as ASCII text - but YOU - if you're the programmer - must understand the format of the data that you'll be working with. With binary data it's every bit as important to get the right bytes in the right places as it is to get the appropriate separators between ...	2011-08-30
3320	Reading the nth line from a file (Perl and Tcl examples) "How do I find the 100th line in a file" - a common question for newcomers to coding. The short answer is to open the file, and loop through to read lines until the one that you want. Although most languages have a seek command or function, that works by bytes and with a typical text / ascii file, ...	2011-06-09
2964	An introduction to file handling in programs - buffering, standard in and out, and file handles Stdout and Stderr Programmers typically don't write code to output to the screen / current window, as to to so would be to provide an inflexible system - instead, they output to what's known as "standard out", also known as stdout. Usually stdout defaults to the screen / current window so there's no ...	2010-09-21 (longer)
1832	Processing all files in a directory - Perl From this week's Perl course: opendir(DH, "."); while ($igot = readdir(DH)) {   next if ($igot =~ /^\.{1,2}$/);   print "igot $igot\n"; } You'll notice that I have used a regular expression to check for files called dot and dot-dot, which are the current and parent directory, as ...	2010-06-23
2405	But I am reading from a file - no need to prompt (Perl) If you're writing a script that calls for user input, you had better prompt the user ... otherwise, the terminal / window will appear to hang and the user won't know what's going on. However - if you're reading your answers from a pre-prepared file or piping them in from another process, all of these ...	2010-06-23
1709	There is more that one way - Perl "There are six ways of doing anything in Perl." So say I on Perl courses and just occasionally I come up with an example that proves it. This one doesn't quite - I show you just five ways of finding the names of all the files in the current directory: $stuff = `ls`;   @fings = glob("*");   opendir(DH,"."); @allfings ...	2008-07-23
1225	Perl - functions for directory handling Perl has many built in functions for file and directory handling and you should use them in preference to shelling out in your scripts because: • They work across operating systems (at least as far as is practical) • They are much more efficient as there's no extra processes being started ...	2007-06-12

ab_file	Using some of the file status operators
af	using the stat function to report on a file
allin	Read and report contents of a directory
chdirddemo	Using directory functions cwd, chdir, opendir, readdir
dend	Data on end of program file
dotty	globbing on a file handle
dxyz	Finding all files with names matching a pattern
f2	Formatting using "format" and "write"
fal	split an incoming file lots of ways
file	_ and $_ in file operators
ft	testing file existence, size and other stats
hunt	Random access to a file of fixed length records
inter	See is STDIN is interactive, and prompt if it is
lowther.pl	Reading data from the end of the program file
segment	Spray one input file across 16 different outputs
whatsmypath	Lists out all duplicate executables