Adding AHCI to centos initrd

Ever needed to add AHCI to a centos system after an install. A quick way to do it is just:

modprobe ahci
cp /boot/initrd-`uname -r`.img /boot/initrd-`uname -r`.img.bak
mkinitrd -f --with=ahci /boot/initrd-`uname -r`.img `uname -r`

UPDATE: on centos6 its now

modprobe ahci
cp /boot/initramfs-`uname -r`.img /boot/initramfs-`uname -r`.img.bak
mkinitrd -f --with=ahci /boot/initramfs-`uname -r`.img `uname -r`

cpanel + rrdtool not installing (new install)

Frequently I came across new cpanel installs not installing rrdtool correctly. The error would end at

Using catalogs: /etc/sgml/sgml-docbook-3.1-1.0-51.el6.cat
Using stylesheet: /usr/share/sgml/docbook/utils-0.6.14/docbook-utils.dsl#print
Working on: /usr/local/cpanel/src/3rdparty/gpl/fontconfig-2.6.0/doc/local-fontconfig-devel.sgml
nsgmls:(invalid location):E: invalid filename ""
rmdir: failed to remove `devel-man': Directory not empty
gmake[2]: *** [func.refs] Error 1
gmake[2]: Leaving directory `/usr/local/cpanel/src/3rdparty/gpl/fontconfig-2.6.0/doc'
gmake[1]: *** [all-recursive] Error 1
gmake[1]: Leaving directory `/usr/local/cpanel/src/3rdparty/gpl/fontconfig-2.6.0'
gmake: *** [all] Error 2
child exited with value 2

To fix run
yum remove docbook-utils
/scripts/rrdtoolinstall

CloudLinux Single mode

I’ve always had trouble getting into single mode in cloudlinux. Trying to type single would show up as gibberish. Looking at a server today, I accidentally came across a way around this, by hitting c (to go to the grub command line) and esc (to exit back). Once done I could use append (a). Previously append or edit did not work.

At the GRUB splash screen at boot time, press any key to enter the GRUB interactive menu.

type c (goes to grub command line) then hit esc

Select Cloud Linux with the version of the kernel that you wish to boot and type a to append the line.

type single and hit enter to boot

Send exim on another IP address, for a specific domain

I was looking for a way to send mail to one domain on an IP, and all other mail on another domain on another IP. The basic exim remote SMTP set up is


remote_smtp:
driver=smtp

To switch the exim ip, the interface=IP.address configuration is used. But I wanted to have email to a particular domain go over another IP address. I came up with

interface = ${if eq {$domain}{REMOTE.DOMAIN.COM} {IP.TO.SEND.FROM}{DEFAULT.IP} }

OpenVZ Container Error

Ran into an issue where an openvz container would start up, but the networking would not. Running in verbose mode I saw

ifup-venet WARNING: Device list is empty

After looking around, searching the web I could not come up with anything. Then I saw the container had an /etc/vz folder. Turned out vzctl had got installed by the user on the openvz container, breaking networking. Removing this and a restart fixed the problem.