The file isn't a Perl script, it's basically a unified diff that is commonly fed into the patch program (originally written by Larry Wall) to apply the patches automatically. Typically, the filename is included in the diff output, so in this case I don't think patch can handle this format, but this patch is simple enough: it's telling you to insert the line "log4perl.appender.Logfile.mode = clobber" after the line "log4perl.appender.Logfile.layout = Log::Log4perl::Layout::SimpleLayout" (as indicated at the top, look at line number 448), and we can infer from the context in this thread that it's referring to t/026FileApp.t in the Log::Log4perl distro.

we can infer from the context in this thread that it's referring to t/026FileApp.t in the Log::Log4perl distro.

Thx, haukex, I had to read all of that very carefully and serially in order to follow along. [I hadn't patched anything before.] A little more context with the new t/026FileApp.t here:

#########################################################
# Print a header into a newly opened file
#########################################################
$data = qq(
log4perl.category         = DEBUG, Logfile
log4perl.appender.Logfile          = Log::Log4perl::Appender::File
log4perl.appender.Logfile.filename = ${testfile}_5
log4perl.appender.Logfile.header_text = This is a nice header.
log4perl.appender.Logfile.layout   = Log::Log4perl::Layout::SimpleLayo
+ut
);

Log::Log4perl->init(\$data);
open FILE, "<${testfile}_5" or die "Cannot open ${testfile}_5";
$content = join '', <FILE>;
close FILE;

is($content, "This is a nice header.\n", "header_text");


# same with syswrite
unlink "${testfile}_5";
$data = qq(
log4perl.category         = DEBUG, Logfile
log4perl.appender.Logfile          = Log::Log4perl::Appender::File
log4perl.appender.Logfile.filename = ${testfile}_5
 log4perl.appender.Logfile.header_text = This is a nice header.
 log4perl.appender.Logfile.syswrite = 1
 log4perl.appender.Logfile.layout = Log::Log4perl::Layout::SimpleLayou
+t
 log4perl.appender.Logfile.mode = clobber
 );

Log::Log4perl->init(\$data);
[download]

I made mistakes on the way to get this, in particular changing the critical line

 log4perl.appender.Logfile.mode = clobber

in Log4perl.pm . I've always wondered how to make changes in the .pm's that are installed on my machine. It seemed like the wrong way to have to change permissions on the file, but I did it, because, hey, we're using force here, right? I added the line and summarily got an error when opening a cpan client window.

After patching the right file and executing:

C:\Users\tblaz\Documents\evelyn\my_repos\Log-Log4perl-1.49>cpanm .
--> Working on .
Configuring Log-Log4perl-1.49 ... OK
Building and testing Log-Log4perl-1.49 ... OK
Successfully installed Log-Log4perl-1.49
1 distribution installed

C:\Users\tblaz\Documents\evelyn\my_repos\Log-Log4perl-1.49>
[download]

, Log4perl.pm was restored to what it was before I started messing with it. I still get a complaint about the Terminal Size, but there is no mention of Log4perl being uninstalled:

Unable to get Terminal Size. The Win32 GetConsoleScreenBufferInfo call
+ didn't work. The COLUMNS and LINES environment variables didn't work
+. at C:\Strawberry\perl\vendor\lib/Term/ReadLine/readline.pm line 410
+.

cpan shell -- CPAN exploration and modules installation (v2.26)
Enter 'h' for help.

cpan>
[download]

Thanks all for comments,

I've always wondered how to make changes in the .pm's that are installed on my machine.

Well, it's possible to patch them directly where they are installed in the @INC paths, but as you've discovered those changes are easily clobbered by a reinstall. So when patching something it's usually better to do so in the distributions before installation. But even in that case there are some chances for conflicts, for example, if you don't change the version number, there is a potential for confusion about whether the patched version is installed or not; and if you simply increment the version number, there is a chance for conflict when the module gets an update by the author. There are several different approaches, listing them all is probably too much, best to cross that bridge if and when you get to it and ask about it then :-) In regards to the question in this thread, note it's about modifying one of the test scripts that don't actually get installed, they only get run before installation to verify that the module was compiled ok on your machine.

Update:

Unable to get Terminal Size. The Win32 GetConsoleScreenBufferInfo call didn't work. The COLUMNS and LINES environment variables didn't work.

See Re: Unable to debug due to terminal problem (read) and Re: Problems starting the debugger