Well, I did not see a Linux-Idiots category, so I decided to post my latest bone head play in this category.

CentOS 5.2

Running Apache/PHP//MySQL from default packages in CentOS.

I recently was reading some, we'll call it "stuff", and decided I needed PCRE installed. Long story short. I downloaded and installed pcre 7.8 by doing
make make install etc....

Now, since then, certain functions in phpBB, which uses php/mysql complain of this:
[phpBB Debug] PHP Notice: in file /includes/functions.php on line 42: preg_match() [function.preg-match]: Compilation failed: this version of PCRE is not compiled with PCRE_UTF8 support at offset 0

hrmmm. Uh yeah, ok, I think. Well, after some investigating, the previous version of PRCE( pcre - 6.6-2.el5_1.7.i386
), which was already installed during my CentOS install, had this UTF8 support already compiled. <looks at self and proclaims one's idiocy at new levels>

Bottom line, my question. How do I revert back to the "already installed" version of PCRE on my Linux box?

Vote for the new category should be started. You and me would be in good company

Let's see what I can do. Either deinstall your own compiled PCRE or recompile with diffrent option should do the trick. Their also might be the chance that your php.ini includes the PCRE module some where. Or just try to reinstall the original module through package managment.

Some programms have a "make uninstall" or "make deinstall" option. Which must be run of the directory where you original run the "make install" command. If there is no make target "de/uninstall" you need to get a list of files the programm puts on the filesystem.

But before going through the hassle of deleting by hand take a look at the compile options of PCRE. "./configure --help" should give you a list. See if you can find the UTF-8 support (or what ever it's called within PCRE) and recompile with
To get a list of files installed during make install compile with the option "--prefix=/tmp/pcre/filelist". After make install /tmp/pcre/filelist contains all the files. You just have to revert the path to your filesystem structure and delete them.

I would just be bold an reinstall the package and see what happens. After that recompile with the --utf8-support option

Good luck and happy compiling
Zhjim

Fixed:

Thanks for the tip.
I recompiled pcre with the following:

#./configure --enable-utf8 --enable-unicode-properties
#make
#make install

Then
# pcretest -C
PCRE version 7.8 2008-09-05
Compiled with
UTF-8 support
Unicode properties support
Newline sequence is LF
\R matches all Unicode newlines
Internal link size = 2
POSIX malloc threshold = 10
Default match limit = 10000000
Default recursion depth limit = 10000000
Match recursion uses stack

I then restarted apache and now my PHP scripts are not complaining.
I actually recompiled the first time without the unicode properties enable, which did not work.

Good to hear everythings working as supposed to.

Cheers zhjim