Changing a timezone on Redhat 7 Linux server is a easy task which can be done on a command line with a few commands. First find your timezone using timedatectl command. The following linux command will list all timezones:
[root@rhel7 ~]# timedatectl list-timezones
To narrow down the search you can use grep to search for a specific city. For example:
[root@rhel7 ~]# timedatectl list-timezones | grep -i bratislava Europe/Bratislava
When not using NTP you may need to set your system time manually. You have two options to set time and date on your RHEL7 linux. First option is to use date command to do this job or engage dedicated systemd timedatectl command. By default and without any arguments timedatectl will display a current time, local, universal and RTC times:
[root@rhel7 ~]# localectl
System Locale: LANG=en_AU.iso88591
VC Keymap: us
X11 Layout: us
[root@rhel7 ~]# timedatectl
Local time: Thu 2014-09-04 18:30:11 WST
Universal time: Thu 2014-09-04 10:30:11 UTC
RTC time: Thu 2014-09-04 10:30:10
Timezone: Australia/Perth (WST, +0800)
NTP enabled: n/a
NTP synchronized: no
RTC in local TZ: no
DST active: n/a
I would like to know how to check gnome desktop manager version on my Redhat 7 Linux server/desktop?
To sync a correct time on your Redhat server with a NTP publicly available time servers first you need to install ntpdate package:
[root@rhel7 ~]# yum install ntpdate
To check your current time use date command:
[root@rhel7 ~]# date Thu Sep 4 17:20:42 WST 2014
Next, we can use pool.ntp.org timeserver to synchronize our time. This is be done with ntpdate command:
[root@rhel7 ~]# ntpdate pool.ntp.org 11 Dec 06:08:13 ntpdate[2225]: step time server 173.230.144.109 offset 8426822.014383 sec
Once you configure NTPD service on your RHEL7 linux you will need to allow traffic through the firewall on port 123. Te following linux command will enable all public traffic on UDP port 123:
# firewall-cmd --zone=public --add-port=123/udp --permanent success
The default settings for the GRUB2 timeout menu selection during the system boot is 5 seconds. To change this value open /etc/default/grub grub default config file. The content of the file looks similar the the one shown below:
GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)" GRUB_DEFAULT=saved GRUB_DISABLE_SUBMENU=true GRUB_TERMINAL_OUTPUT="console" GRUB_CMDLINE_LINUX="rd.lvm.lv=rhel/root crashkernel=auto \ rd.lvm.lv=rhel/swap vconsole.font=latarcyrheb-sun16 vconsole.keymap=us rhgb quiet" GRUB_DISABLE_RECOVERY="true"
This config will describe a procedure on how to persistently load kernel modules during a boot time on CentOS or Redhat Linux system. In the below commands will use nf_conntrack_pptp as a sample module. Replace the name of this module with a module name you wish to load.
First, create a script within /etc/sysconfig/modules/ directory with a file extension modules. Where the name of the script can be any name of your choice. In our case the script will be called nf_conntrack_pptp.modules. Enter a following code into your new nf_conntrack_pptp.modules script while replacing the name of the module with the one you wish to load:
#!/bin/sh exec /sbin/modprobe nf_conntrack_pptp >/dev/null 2>&1
When trying to start a service with service or systemctl commands on the Redhat 7 Linux system the following error message can appear on the screen:
Failed to issue method call: Unit service_name.service failed to load: No such file or directory.
Chrome browser is not a part of standard Redhat repositories and therefore its installation needs to be performed using external package provided by Google Inc. First download chrome browser package:
[rhel7@rhel7 ~]$ wget https://dl.google.com/linux/direct/google-chrome-stable_current_x86_64.rpm
There are two handy tools to help you provide an additional information about system packages. The first tool is the package manager yum and the second is yumdb. Both tools display a different type of information. The other difference is that yumdb command can be only used on packages currently installed on the system.
Installation of Memtest+ RAM memory test tool on Redhat 7 Linux
Memtest is a quite handy tool when troubleshooting hardware problem and specifically problems related to Random Access Memory (RAM). After installation the memtest+ tool will become available among other boot options. To install memtest+ on RHEL 7 Linux server execute the following linux command:
# yum install memtest86+ ... Running transaction Installing : memtest86+-4.20-12.el7.x86_64 1/1 Verifying : memtest86+-4.20-12.el7.x86_64 1/1 Installed: memtest86+.x86_64 0:4.20-12.el7
Resetting the root password in RHEL7/CentOS7/Scientific Linux 7
RHEL7 / CentOS7 / Scientific Linux 7
MODERATE
Things have changed in the RHEL7 world and so has the preferred way of resetting the root password. Although the old way of interrupting the boot process (init=/bin/bash) still works, it is no longer bulletproof and recommended.
‘Systemd’ uses ‘rd.break’ to interrupt the boot. Let’s have a quick walk through the whole procedure.