If you're ever had to manage a cPanel server, you've probably had a request from a customer to install Subversion, and you probably tried the Yum package manager to install it.
root@server [~]# yum install subversion
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
* addons: mirror.cogentco.com
* extras: yum.singlehop.com
Excluding Packages in global exclude list
Setting up Install Process
subversion-1.4.2-4.el5_3.1.x86_64 from base has depsolving problems
--> Missing Dependency: perl(URI) >= 1.17 is needed by package subversion-1.4.2-4.el5_3.1.x86_64 (base)
cPanel is written in Perl, so the cPanel software maintains it's own Perl installation and blocks Yum from installing Perl deps. The cPanel /scripts/perlinstaller utility will show that the module needed is installed, yet Yum will not proceed.
I used to download the per-uri RPM from rpmfind.net for my version of CentOS and install it. But an associate of mine showed me an easier way.
The very first line:
exclude=apache* bind-chroot courier* dovecot* exim* httpd* mod_ssl* mysql* nsd* perl* php* proftpd* pure-ftpd* ruby* spamassassin* squirrelmail*
Remove “perl*” from that line. Save and quit.
Now, install subversion. It should resolve the perl-URI dependency just fine.
Once it's completed, don't forget to edit the yum.conf file and restore the “perl*” to the exclude line, so Yum doesn't interfere with cPanel's Perl modules.