Meaning of "Processing triggers for ureadahead"

Question

I am trying to uninstall Tomcat 7 from Ubuntu 12.04 by issuing the command

sudo apt-get remove tomcat7

as a result I am getting the following response

My Questions

1. Has the package tomcat7 been removed? If yes, why don't the message stating so has not been printed and if no why it has not been removed?

2. What is the meaning of "Processing triggers from ureachahead..."?

Solution 1

Yes it has been removed. If you issue the removal command again you will see an error stating that Tomcat is not installed.

ureadahead is a mechanism whereby anything that is required to be loaded at boot time is marked as such and the location is noted. This speeds up boot time because the filesystem doesn't have to go searching for the files before loading them. As you can imagine, when you install or remove modules some of them may have to be added or removed from ureadahead to keep it up to date. It's normal mechanism in modern Linux operating systems like Ubuntu.

Solution 2

1) Yes

2) Packages can subscribe to filesystem events, such as files being added to a certain directory. Packages can also trigger other packages manually. This is done to prevent e.g. update-initramfs to be run many times during a dist-upgrade. Each relevant package now triggers the update-initramfs tool, but it gets run only once, at the end.

Comments

[fabricator4]

BTW, you have two packages waiting to be installed. Most likely it is a kernel update which will not be done with a normal 'apt-get updgrade' because there will be dependency issues that will need to be resolved. Use the automatic updater, or issue the command 'sudo apt-get dist-upgrade' which will do the same thing.