HOWTO: Free up space of CentOS Linux 7.x

a) Install Yum utilities:

yum install yum-utils

b) Delete largest log files if necessary:

rm -frv /var/log/<filename>

c) Trim log files:

find /var -name "*.log" \( \( -size +50M -mtime +7 \) -o -mtime +30 \) -exec truncate {} --size 0 \;

d) Clean up Yum cache:

yum clean all
rm -rf /var/cache/yum
rm -rf /var/tmp/yum-*

e) Remove orphan packages:

package-cleanup --quiet --leaves --exclude-bin
package-cleanup --quiet --leaves --exclude-bin | xargs yum remove -y

f) Remove old kernels:

package-cleanup --oldkernels --count=2