For 2023 - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Perl - its up to YOU to check your file opened
When you open a file in Perl, you should ALWAYS check the return status to see if your open function worked. If it can't open the file you've requested it won't print out an error - the failure is silent unless you check for it.
open (FH,"abc.txt") or die ("Cannot open abc.txt\n");
Perl will fail to open a file for read if the file does not exist, or if the file is not readable by the user requesting it
open (FH,">abc.txt") or die ("Cannot open abc.txt\n");
Perl will fail to open a file for write if the user running the Perl program does not have appropiate write permissions. A file can be opened for write whether or not it already exists; if it does exist the open statement shown will cause the existing content to be deleted. (written 2006-02-23, updated 2006-06-05)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articlesP207 - Perl - File Handling 
How many people in a room? - (2004-08-12) 
Relative or absolute milkman - (2004-11-10) 
STDIN, STDOUT, STDERR and DATA - Perl file handles - (2005-03-23) 
printf - a flawed but useful function - (2006-02-22) 
Iterators - expressions tha change each time you call them - (2006-04-27) 
Being sure to be positive in Perl - (2006-09-15) 
Some one line Perl tips and techniques - (2007-08-21) 
Good, steady, simple example - Perl file handling - (2007-10-30) 
Reading a file multiple times - file pointers - (2007-11-23) 
stdout v stderr (Tcl, Perl, Shell) - (2007-12-10) 
There is more that one way - Perl - (2008-07-14) 
Formatting with a leading + / Lua and Perl - (2008-10-15) 
Seven new intermediate Perl examples - (2008-10-30) 
Reactive (dynamic) formatting in Perl - (2008-10-31) 
Transforming data in Perl using lists of lists and hashes of hashes - (2009-06-12) 
But I am reading from a file - no need to prompt (Perl) - (2009-09-14) 
File open and read in Perl - modernisation - (2010-06-19) 
Chancellor George Osborne inspires Perl Program - (2010-06-22) 
Fresh Perl Teaching Examples - part 2 of 3 - (2010-06-27) 
Finding your big files in Perl - design considerations beyond the course environment - (2011-06-14) 
Dark mornings, dog update, and Python and Lua courses before Christmas - (2011-12-10) 
Traversing a directory in Perl - (2012-08-08) 
Spraying data from one incoming to series of outgoing files in Perl - (2012-08-15)
Some other Articles
Queues and barrel rolls in PerlAnd the staff put the icing on the cakeFamiliar names, close to homeIf its Sunday, it must be the NorlandPerl - its up to YOU to check your file openedEasy, Free, Reliable internet accessLooking for leading not bleeding edgeNews in IrelandGreetings from Dublin
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This is a page archived from The Horse's Mouth at
the diary and writings of Graham Ellis.
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