====== CentOS ======

http://www.centos.org

===== NetInstall URL =====

==== CentOS 6 ====

http://mirror.centos.org/centos/6/os/x86_64

==== CentOS 7 ====

http://mirror.centos.org/centos/7/os/x86_64
===== Změna hostname =====

V **/etc/sysconfig/network** změnit proměnou **HOSTNAME** a v **/etc/hosts**.

**Tohle nestačí na permanentní změnu!**

<code>
shell# hostname bflmpsvz
</code>

==== Permanentní změna pro Centos 7.X ====

<code>
shell# hostnamectl set-hostname name
</code>
===== YUM =====

<code>
shell# yum clean metadata
shell# yum clean all
shell# yum update
shell# yum install yum-plugin-security.noarch
shell# yum updateinfo list --security --quiet
shell# yum repolist
</code>

Dokončení transakce

<code>
shell# yum install yum-utils.noarch
shell# yum-complete-transaction
</code>

Spadlá transakce - mazání duplicit

<code>
shell# package-cleanup --cleandupes
</code>
===== EPEL repository =====

<code>
shell# wget http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm
shell# rpm -ivh epel-release-6-8.noarch.rpm
</code>

===== Instalace PDFtk =====

http://www.pdflabs.com/docs/install-pdftk-on-redhat-or-centos/

<code>
shell# yum install glibcj
shell# rpm -i pdftk-*.rpm
</code>

**Sloučení PDF dokumentů**

<code>
shell> pdftk file1.pdf file2.pdf cat output final.pdf
</code>

===== Automatic security updates =====

https://serversforhackers.com/video/automatic-security-updates-centos

<code>
shell# yum upgrade
shell# yum --security upgrade
shell# yum --security upgrade-minimal
</code>

===== Nefunkční rsyslog =====

<file log /var/log/messages>
...
... rsyslogd-3000: sd_journal_get_cursor() failed: 'Cannot assign requested address'
...
</file>

<code>
shell# rm -f /var/lib/rsyslog/imjournal.state
shell# systemctl restart rsyslog.service
shell# systemctl status rsyslog.service
</code>

===== Free up space on CentOS/RHELL /boot safely =====

<code>
shell# yum remove `rpm -q kernel | grep -v 'uname -r'`
</code>

===== CentOS 7 iptables =====

<code>
shell# systemctl disable firewalld
shell# yum install -y iptables-services
shell# systemctl enable iptables
</code>

/etc/sysconfig/iptables