Sometimes you get the following warning when running commands in Debian / Ubuntu powered computers
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perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LANG = “en_US.UTF-8″
are supported and installed on your system.
perl: warning: Falling back to the standard locale (”C”).
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To fix this run the following command as root
root@php-server:~# apt-get [...]

Sometimes you may get the following error while working with yum:
root@server2 [~]# yum install kernel-smp
Setting up Install Process
Setting up repositories
update 100% |=========================| 951 B 00:00
base [...]