In this lab, we are going to practice scheduling updates, modifying NTP settings, and changing what kernel the server will reboot into.
Understanding how to do these tasks will prepare you for various administrative duties in the future.
*This course is not approved or sponsored by Red Hat.*
Learning Objectives
Successfully complete this lab by achieving the following learning objectives:
- Schedule a Job Using the `at` Utility
To schedule commands using the
atcommand, you can runat 12:00amat> yum update -yPressing
Ctrl+Dwill show a message, then send you back to the shell.at> <EOT>You can run
atqto verify that the command is scheduled.If you get an error similar to:
Can't open /var/run/atd.pid to signal atd. No atd running?That means that the atd service isn’t running. You can resolve that by running
systemctl start atd- Modify the NTP Pools to Keep Clocks Synchronized
NTP configuration is set in
/etc/chrony.conf.The lines that need to be modified are at the top of the file. Edit them to look like:
server 0.pool.ntp.org iburstserver 1.pool.ntp.orgserver 2.pool.ntp.orgserver 3.pool.ntp.org- Modify GRUB to Boot a Different Kernel
List the currently installed kernels with
grubby --info=ALLFind the line that looks like
index=1You’ll see information about that kernel following the index.
Run
grubby --set-default-index=<index number>Run
grubby --default-indexto verify it worked.
