Using proxy

To enable proxy access for a specific user, add the lines in the example box below to the user's shell profile. For the default bash shell, the profile is the file ~/.bash_profile. The settings below enable yum to use the proxy server mycache.mydomain.com, connecting to port 3128.

# The Web proxy server used by this account
http_proxy="http://mycache.mydomain.com:3128"
export http_proxy

If the proxy server requires a username and password, add these to the URL. To include the username yum-user and the password qwerty, add these settings:

# The Web proxy server, with the username and password for this account
http_proxy="http://yum-user:[email protected]:3128"
export http_proxy

See details on https://www.centos.org/docs/5/html/yum/sn-yum-proxy-server.html

Useful commands

yum list installed
yum search ***
yum localinstall *.rpm
yum erase ***

Install locate command

sudo yum install mlocate
sudo updatedb

See details on http://askubuntu.com/questions/215503/how-to-install-the-locate-command

Update exclude package

yum update --exclude=PACKAGENAME

See details on https://access.redhat.com/solutions/10185

Enable EPEL Repository

This works on CentOS 7:

yum install epel-release

If it doesn't work, do it manually:

wget http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-8.noarch.rpm
rpm -ivh epel-release-7-8.noarch.rpm

See details on http://www.tecmint.com/how-to-enable-epel-repository-for-rhel-centos-6-5/

Install Google Chrome

• Create /etc/yum.repos.d/google-chrome.repo with the following content:

  [google-chrome] name=google-chrome baseurl=http://dl.google.com/linux/chrome/rpm/stable/$basearch enabled=1 gpgcheck=1 gpgkey=https://dl-ssl.google.com/linux/linux_signing_key.pub

• Install by yum

  sudo yum install google-chrome-stable

See details on http://www.tecmint.com/install-google-chrome-on-redhat-centos-fedora-linux/

Purge Old Kernels

• Install yum-utils.

  yum install yum-utils

• Clean old kernels and only keep two latest kernels.

  package-cleanup --oldkernels --count=2

• To keep fewer kernels automatically edit /etc/yum.conf and change installonly_limit=2.

See details on https://www.centos.org/forums/viewtopic.php?t=2120

Install Fonts

sudo yum groupinstall "Fonts"

See details on https://ask.fedoraproject.org/en/question/7032/how-do-i-install-fonts-in-fedora/

Accept insecure SSL certificate

• Add the following in /etc/yum.conf

sslverify=false

• Add repo

sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo 

• Add the following in /etc/yum.repos.d/docker-ce.repo

sslverify=0

• Change /etc/yum.conf back.