Not checking if 'open' was successful

There are several programming issues in the following examples:

examples/try_to_read_log_file.pl

use strict;
#use warnings;

my $filename = '/tmp/application.conf';

open(F, "<$filename");
while(<F>) {
   # do something with $_
}
close F;

If we run this script it will run silently regardless of the existence of the file /tmp/application.conf it tries to read.

If we turn on use warnings as recommended then, if the file we are trying to open does not exists we'll get a run-time warning:

readline() on closed filehandle F at ...

The real problem of this code is that we don't check the return value of open.

The recommended way to open a file is to either write

open ... or die ...

or to write

if (open ...) {

}

but in this case the author have forgotten to protect the code in case the file is missing or cannot be read for some other reason.

The solution is to use either of the above construct.

There is another issue of opening the file in the old way instead of the recommended 3-argument open, but the main issue is the lack of error checking.

Conclusion

Always use strict and always use warnings.

They can protect you from certain programming mistakes.

Comments

I think you forgot to actually use readline() in your example code. also, why would you name the life "try_to_read_log_file.pl" when you are opening an obviously config file? :-)

---

Why not add in an existence check on the file itself before the open command? Both are better since this is not an atomic operation.

if ( -f $filename ) { open F, '<:encoding(utf8)', $filename or die "$!: $filename"; BLAH BLAH BLAH; close F; }

NOTE: Depending on the usage, the "-s" test may be better to see if the file size is > 0.

@flamey : simple - the conf file references the log files so you can open them later in the code. : )