Installing via the pecl command can be a pain on Redhat. First off all you will need to install the php-devel package:

yum install php-devel

Then you will need ensure that the PEAR/PECL installer is at the latest version so as root run:

pear update-channel pear.php.net
pear upgrade pear

You may need to force pear to upgrade itself by using:

pear upgrade —force pear

I had to use the —force option because my version of PEAR was so old that the installer thought my version of Tar_Archive might not have been up to muster. It was however.

With all this in place you are ready to attempt to install your chosen extension:

pecl install ssdeep

If you get something like the following back:

/usr/bin/phpize: /tmp/ssdeep/build/shtool: /bin/sh: bad interpreter: Permission

Then it is likely that your temporary directory is mounted in a safer noexec state, which means that you cannot execute scripts within the /tmp directory. To test this you can put a simple bash script into your /tmp directory and chmod it with +x. I used the following bash script:

#!/bin/bash
echo “SIMON” 

If you do not get SIMON back when you execute the file, but an error like “/bin/sh: bad interpreter: Permission” then the directory is set to noexec.

There are a few ways to overcome this with the easiest being to:

1. Remount the directory as exec:

   mount -o remount,exec /tmp

2. Install your pecl extension

   pecl install ssdeep

3. Remount the directory as noexec again for safety

   mount -o remount,noexec /tmp

There are a variety of other ways to get this working documented in the Media Temple wiki pages if the above technique does not work for you.

Installing APC on Redhat is as simple as:

[user@server directory]# yum install php-pecl-apc

APC should now be ready to run on your server.  Try running the following command to verify it is setup; you should get something in response like mine:

[user@server directory]# php -r ‘phpinfo();’ | grep ‘apc’
apc
MMAP File Mask => /tmp/apc.s5jA6w
apc.cache_by_default => On => On
apc.coredump_unmap => Off => Off
apc.enable_cli => On => On
apc.enabled => On => On

<…SNIP…>

Now lets move onto installing Memcached, which again is very simple:

[user@server directory]# yum install memcached
[user@server directory]# /etc/init.d/memcached start

The PHP Memcached module can be installed through YUM as well:

[user@server directory]# yum install php-pecl-memcache

Now to configure PHP to use Memcached to store the session information we need to edit our /etc/php.d/memcache.ini file and jump to the bottom of the file where we uncomment the following lines by removing the preceeding semicolon (‘;’):

; Options to use the memcache session handler

; Use memcache as a session handler
;session.save_handler=memcache
 ; Defines a comma separated of server urls to use for session storage
;session.save_path=”tcp://localhost:11211?persistent=1&weight=1&timeout=1&retry_interval=15″

So that it now looks like this:

; Options to use the memcache session handler

; Use memcache as a session handler
session.save_handler=memcache
 ; Defines a comma separated of server urls to use for session storage
session.save_path=”tcp://localhost:11211?persistent=1&weight=1&timeout=1&retry_interval=15″

That just leaves us to restart the Apache/HTTPd process:

[user@server directory]# /etc/init.d/httpd restart

You are now up and running with Memcached PHP sessions and APC served PHP.