There are two types:

• Soft links
• Hard links

Your locale tells the computer your location, preferred time-and-date format, standard language, papersize, et c. A list of supported locales is available at /usr/share/i18n/SUPPORTED

See a full list with:

1cat /usr/share/i18n/SUPPORTED

Take the first portion to generate full locale information for a region:

1 …

Type

type shows what kind of thing you're running, be it an alias, function, or binary program.

1type cmus

<img
  loading="lazy"
  decoding="async"
  alt="where is cmus?"
  
    class="image_figure image_internal …</picture></figure></p>

Basic

Keeping track of health problems. Mostly under /var/log/.

These logs are created by syslogd (or syslog in earlier distros).

Rundown

`alternatives.log' has a bunch about other programs installing things around 5 times a day. This includes x-www-browser, which sets the default browser (supposedly - this doesn't …

Firstly, your ls is probably aliased to something.

Check it with:

1alias ls

If the prompt shows some alias, then start by removing it:

1unalias ls

Now we can begin.

Check the most recently modified file:

1ls -t

Reverse this with tac to see the file which has been unmodified the longest:

1ls -t | tac

Group files by …

Basics

A service can consist of two files - the .sh script to run, and the .service file which describes its run conditions.

The .service file goes in /etc/systemd/system. The scripts themselves might be best placed in $HOME/.local/bin.

Example - tracker.service

1[Unit]
2Description=Tracker
3
4[Service]
5Type=simple
6 …

Turn a markdown file into a pdf:

1lowdown -stms "$FILE".md | pdfroff -itk -mspdf > "$FILE".pdf

Example: put this Makefile in a directory, rename it Makefile, then do:

1make example
2make

To give the document a title, put that title in the metadata:

1sed -i "1 i---" "$FILE".md
2sed -i …

RAID5

You will need 4 disks and the mdadm package. The total size will be equal to the disks x 3, because one will be used for redundancy.

1sudo mdadm --create --verbose /dev/*md127* --level=5 --raid-devices=*4* */dev/sdb /dev/sdc /dev/sdd /dev/sde*

Note the variable parts:

• The name of the device could be /dev/md12 or …

See screen size

xrandr -q

Automatically configure:

xrandr --auto

Print the average CPU load over 1 minute, 5 minutes, and 15 minutes:

1watch -d cat /proc/loadavg
2stress="$(cat /proc/loadavg | awk '{print "Usage:" $2"%"}')"

Show memory usage in Gibitytes.

1free -g

Show low and high gigibtye usage on a line, and repeat the measurement every 5 seconds: …