Useful commands

Services:
We use "httpd" as an example service. Substitute it as needed in the command below

Check if any processes are running for the service
pgrep httpd
If there are any processes running, the PID (process ID) will be listed, else the command returns silently

Stop a service
/sbin/service httpd stop

Start a service
/sbin/service httpd start

Check the status of a service
/sbin/service httpd status

Check which run-levels a service is enabled for
/sbin/chkconfig httpd --list

Enable a service to run in regular run-levels
/sbin/chkconfig httpd on

Installing software rpms:
Install
rpm -ivh <rpm-name>

Upgrade
rpm -Uvh <package-name>

Querying the presence of a package
rpm -q <package-name>

checking a package file
rpm -K /path/to/<full-package-filename>

Backing up a file:
cp -p filename filename.bak

Apache configuration and startup/shutdown/reload

Check Apache configuration syntax
/usr/sbin/apachectl -t

List virtual hosts in Apache configuration
/usr/sbin/apachectl -S

Stop/start Apache
/usr/sbin/apachectl stop (or /usr/sbin/apachectl start)

Shutdown the system (immediately)
/sbin/shutdown -h now

Reboot the system (immediately)
/sbin/shutdown -r now

END-OF-FILE