Useful Yum commands

Few useful yum commands

1. yum list installed - Gives a list of already installed packages
2. yum history list   - Gives a list yum installs. Note that one can install multiple packages and their dependencies in a single invocation. Example, yum install docker-ce, docker-ce-cli
3. yum history info   - Gives the details of yum invocation for each of the historical entry above.
4. /var/log/yum.log - also contains log of yum installs
5. yum list docker-ce --showduplicates | sort -r  - Shows all the versions that are present for docker and sorts them.

To find difference in packages between installs -

• Before installation - 

rpm -qa --qf '%{NAME}.%{ARCH}\n' | sort > old-installed-rpms.txt

• After installation - 

rpm -qa --qf '%{NAME}.%{ARCH}\n' | sort > new-installed-rpms.txt

• Diff - 

diff old-installed-rpms.txt new-installed-rpms.txt | grep '^<'

tar destination directory

tar by default extract's to the current directory, if that needs to be changed, it can be done by using below -

[rakesh@host2] tar zxvf source.tar -C /your/dest/dir/to/extract

Graphic display in Linux

In Oracle Linux Virtual Box VM, by default the graphic output is disabled. Login as root (su) and edit the file /etc/inittab as shown below

Subsequently from the command prompt run startx to start the graphic display.

It's possible that despite the above changes, errors like below may occur

[bea@vin2 Desktop]$ java -jar wls1036_generic.jar 
Xlib: connection to ":0.0" refused by server
Xlib: Invalid MIT-MAGIC-COOKIE-1 key
Unable to instantiate GUI, defaulting to console mode.

Solution:

Login as root and copy and override the .Xauthority from root's home folder to the user's home folder. As a precaution, take a backup of the user's .Xauthority file.

You can check if the graphic display is working or not by running xclock