CONTINUAL INTEGRATION

Problem scenario
There is unaccounted for hard drive space missing. There is a discrepancy with the hard disk specifications of your machine and what you see during the installation of Linux (e.g., Ubuntu, RHEL, Stream Fedora, SUSE etc.). You are trying to designate an installation destination of the OS. Where is the missing space?

Possible Solutions
There are multiple potential root causes for this situation.

Possible Solution #1
Do a factory reset. WARNING: This will delete all of your data on the disk. Only do this if you do not need any files on your server. When you boot up press F11 repeatedly (for HP https://www.businessinsider.com/how-to-factory-reset-hp-laptop or Lenovo https://smallbusiness.chron.com/reformat-lenovo-laptop-54339.html). With Dell you log in https://www.gadgetsalvation.com/blog/2021/08/10/how-to-factory-reset-a-dell-laptop/. For some Lenovos you will use a physical button described in this video: https://support.lenovo.com/us/en/videos/vid100759-how-to-reset-your-laptop-to-factory-defaults-using-lenovo-onekey-recovery-okr

Possible Solution #2
This will delete all the data on your laptop.Sometimes a bootable .iso of a trial Windows OS can help you reformat and consolidate the disk space. Using Rufus (the installation tool) and a free version of Windows, you could reallocate disk space.

Possible Solution #3
See this posting: https://unix.stackexchange.com/questions/457721/usb-boot-install-linux-not-recognizing-disk-space

Possible Solution #4
See this Quora posting. It explains that there is no actual problem. As does this answer.

Problem scenario
You are running Linux. You think quotas are not properly configured. You run "repquota -au" and see soft and hard limits. You see grace periods. But you are not sure if quotas are enabled or not. What should you do?

Solution
Run this:

sudo quotaon -ap

To enable groups, run this:

sudo quotaon -ag

To enable user quotas, run this:

sudo quotaon -au

We tend to think user quotas make more sense because files have groups associated with them of the user that created them. But only one user can be associated with one such group. Conceptually it seems easier to grasp if you user user quotas than group quotas.

Problem scenario
You are using Ubuntu Text Editor. You want to redo an undone change. How do you accomplish this?

Solution
Right click somewhere in the text.
Go to "Redo"

Problem scenario
The grace period says "none". Clearly the grace period expired. The soft limit has been exceeded and maybe even the hard limit has exceeded. Files are still created. You would expect to see a "write failed…quota reached" or "quota exceeded" any time a user tried to create a new file or directory. What should you do?

Solution
Run this:

quotaon -ap

Problem scenario
You want to combine several PDF files. But you don't want to upload them to a website. How do you do this for free with a Debian distribution of Linux?

Solution
Run this command:

sudo apt -y install poppler-utils

Run this command (where 1.pdf is the first file you want to be merged with the first pages, foobar.pdf is a file you want in the middle of your single PDF result, and last.pdf is the pdf with the last pages you want in a final combined PDF called combination.pdf):

pdfunite 1.pdf foobar.pdf last.pdf combination.pdf

# Note this assumes you have in your directory files called 1.pdf, foobar.pdf, and last.pdf.

Question
You have seen "<(" in Linux. What does it do?

Answer
A command encapsulated in parens and having the "<" symbol on the left is a way to do process substitution.

Here is an example:

diff <(hostname -f) <(date)

The diff command can compare the results of two different commands. To read more about process substitution, see this posting: https://tldp.org/LDP/abs/html/process-sub.html