The /proc filesystem /proc/uptime
This file contains the length of time since the system was booted, as well as the amount of time since then that the system has been idle. Both are given as floating-point values, in seconds.
Example output:
[fedora@fedora ~]$ cat /proc/uptime
3677.44 1898.50
[fedora@fedora ~]$ uptime
22:58:03 up 1:01, 2 users, load average: 0.24, 0.29, 0.32
[fedora@fedora ~]$
[root@fedora ~]#
How to Speed up NTP initial synchronization
Open the NT P configuration file /etc/ntp.conf in a text editor such as vi or nano, or create a new one if it does not already exist:
To speed the initial synchronization up, add the iburst directive at the end of each server line:
server 0.rhel.pool.ntp.org iburst
server 1.rhel.pool.ntp.org iburst
server 2.rhel.pool.ntp.org iburst
About Redhat subscription-manager
subscription-manager tool. This tool has the following format:
# subscription-manager command [options]
[root@fedora ~]#
Each command has its own set of options that are used with it. The subscription-manager help and manpage have more information.
Example:
subscription-manager Commands
—————————–
Command | Description
—————————–
register - Registers or identifies a new system to the subscription service.
unregister - Unregisters a machine, which strips its subscriptions and removes the machine from the subscription service.
subscribe - Allocates a specific subscription to the machine.
Linux Network Time Protocol Setup
We can also synchronize the system clock with a remote server over the Network Time Protocol ( NTP).
For the one-time synchronization only, use the ntpdate command:
Check whether the selected NTP server is accessible:
[root@fedora ~]# ntpdate -q 0.rhel.pool.ntp.org
server 202.71.136.67, stratum 2, offset 0.014709, delay 0.25420
server 119.226.101.130, stratum 2, offset -0.007991, delay 0.21991
3 Oct 09:40:35 ntpdate[4083]: adjust time server 119.226.101.130 offset -0.007991 sec
[root@fedora ~]#
Run the ntpdate command followed by one or more server addresses:
[root@fedora ~]# ntpdate 0.rhel.pool.ntp.org 1.rhel.pool.ntp.org
3 Oct 09:41:36 ntpdate[4092]: adjust time server 119.226.101.131 offset 0.000724 sec
Enable the service.
[root@fedora ~]# systemctl status ntpd.service
ntpd.service - Network Time Service
Loaded: loaded (/usr/lib/systemd/system/ntpd.service; enabled)
Active: inactive (dead) since Wed, 03 Oct 2012 09:42:42 +0530; 36s ago
CGroup: name=systemd:/system/ntpd.service
Oct 03 09:42:42 fedora.example.com ntpd[4105]: ntpd 4.2.6p5@1.2349-o Fri Apr 27 08:37:16 UTC 2012 (1)
The cgconfig Service
The cgconfig service installed with the libcgroup package provides a convenient way to create hierarchies, attach subsystems to hierarchies, and manage cgroups within those hierarchies. It is recommended that you use cgconfig to manage hierarchies and cgroups on your system.
The cgconfig service is not started by default on Red Hat Enterprise Linux 6. When you start the service with chkconfig, it reads the cgroup configuration file — /etc/cgconfig.conf. Cgroups are therefore recreated from session to session and become persistent. Depending on the contents of the configuration file, cgconfig can create hierarchies, mount necessary file systems, create cgroups, and set subsystem parameters for each group.
The default /etc/cgconfig.conf file installed with the libcgroup package creates and mounts an individual hierarchy for each subsystem, and attaches the subsystems to these hierarchies.
If you stop the cgconfig service (with the service cgconfig stop command), it unmounts all the hierarchies that it mounted.
Reference: http://redhat.com
