linux-bible

A collection of most commonly used Linux commands & tools, articles, & settings.

CHEAT SHEET:

Linux Cheat Sheet

1. Change default screenshot directory:

Edit this file using dconfeditor

org/gnome/gnome-screenshot/auto-save-directory --> "file:///home/talha/Pictures/ScreenShots/"

gsettings set org.gnome.gnome-screenshot auto-save-directory "file:///home/$USER/Pictures/ScreenShots/"

2. Change ubuntu dock settings:

how-to-customize-dock-panel-on-ubuntu

sudo apt install dconf-editor
gsettings set org.gnome.shell.extensions.dash-to-dock extend-height false
gsettings set org.gnome.shell.extensions.dash-to-dock dock-position BOTTOM
gsettings set org.gnome.shell.extensions.dash-to-dock transparency-mode FIXED
gsettings set org.gnome.shell.extensions.dash-to-dock dash-max-icon-size 64
gsettings set org.gnome.shell.extensions.dash-to-dock unity-backlit-items true

3. Add a new user:

sudo adduser user

4. Add user to sudoers group:

sudo usermod -a -G sudo user

5. Play MIDI (.mid) Files in Linux:

sudo apt install vlc vlc-plugin-fluidsynth

6. My monitor only supports 1366x768. How to take 2K or 4K Screenshots?

1st Run this command in your terminal: cvt 3840 2160 for 4K in this case (Change the Res Accordingly).

Then copy the output on 2nd line after Modeline.

Below is an exaple output

╭─talha@Manjaro in ~
 ╰─λ cvt 3840 2160
# 3840x2160 59.98 Hz (CVT 8.29M9) hsync: 134.18 kHz; pclk: 712.75 MHz
Modeline "3840x2160_60.00"  712.75  3840 4160 4576 5312  2160 2163 2168 2237 -hsync +vsync

 ╭─talha@Manjaro in ~ via  v3.10.9 took 48ms
 ╰─λ 

eDP-1 is - in my - case - the Primary Monitor name, which can be found using xrandr command. Find yours by just typing xrand in your terminal...

Here's an example:

And then use these commands, replace eDP-1 with your monitor name :

xrandr --newmode "3840x2160_60.00"  712.75  3840 4160 4576 5312  2160 2163 2168 2237 -hsync +vsync
xrandr --addmode eDP-1 3840x2160_60.00

To use the new resolution:

xrandr -s 3840x2160_60.00

To take low compression, high quality screenshots, type:

scrot -q 100 -d 3

7. Find/Sort all files in the current dir WRT their size:

find . -type f -exec du -h {} \; | sort -h

Reverse the sort order with -r i.e. larger files first:

find . -type f -exec du -h {} \; | sort -hr

8. Find the size of all hidden files and directories (dot files & dirs) & sort them wrt size:

Dot directories are usually found in the $HOME (~) folder and are hidden by default...

find . -maxdepth 1 -type d  -iname ".*" -exec du -sh {} \;  | sort -h

9. Kill all processes of current logged in user (equivalent to logout):

ps -fu $USER | awk '{print "kill -9 " $2}' | sh

OR

killall -u $USER

10. Create & Extract tar Files:

To create a simple tar file from a given dir use:

tar -cf Pictures.tar Pictures/

To extract a tar file:

tar -xf Pictures.tar

For verbose output, use -v option:

tar -cvf Pictures.tar Pictures/

tar -xvf Pictures.tar

• -c : create
• -x : Extract (the oposite of create)
• -f : specify a filename (comes always at the end)
• -v : verbose output
• -z : compress with gzip (Create .tar.gz files
• -j : compress with bzip2 (Create .tar.gz2 files)
• -J : compress with xz (Create .tar.xz files)
• -t : list contents of archive

To create a .tar.gz file:

tar -czf Pictures.tar.gz Pictures/

To extract a .tar.gz file:

tar -xzf Pictures.tar.gz Pictures/

To create a .tar.gz2 file:

tar -cjf Pictures.tar.gz2 Pictures/

To extract a .tar.gz file:

tar -xjf Pictures.tar.gz2 Pictures/

To create a .tar.xz file:

tar -cJf Pictures.tar.xz Pictures/

To extract a .tar.xz file:

tar -xJf Pictures.tar.xz Pictures/

Use Multi-Threading to Creacte/Extract tarballs:

To use all the resourses to speed up the process we can (in BASH):

XZ_DEFAULTS="--threads=4"; export XZ_DEFAULTS;

tar -cJvf archive.tar.xz Pictures/

or in ZSH:

set XZ_DEFAULTS "--threads=4"; export XZ_DEFAULTS;

Or we can provide -I, --use-compress-program=PROG option to use a given compression program instead of default gzip, bzip2 or xz programs:

pigz, pbzip2 & pxz are the PARALLEL Implementaions of the gzip, pbzip2, & xz respectively.

These can be installed using apt in Ubuntu:

sudo apt install pigz pbzip2 pxz

Which are just the PARALLEL implementations of the given programs (Parallel Implementation of gzip, pbzip2, & xz)

If you're using Ubuntu 20.04, the pxz program is not available in default repos. So you can add bionic (Ubuntu 18.04) main universe repo to install this program:

sudo apt edit-sources

And then add this line at the end of the file:

deb http://cz.archive.ubuntu.com/ubuntu bionic main universe

Then install the pxz program:

sudo apt install pxz

To use these programs instead of defaults we can provode flags like this:

tar -I pxz -cvf Pictures.tar.xz Pictures/
tar -I pigz Pictures.tar.gz Pictrures/
tar -I pbzip2 Pictures.tar.gz2 Pictrures/

Or even we can provide default gz option with additional flags: -9 means compression level 9 (maximum compression)

tar -c -I 'xz -9' -f archive.tar.xz Dir/

-T0 means to use all the available threads (I Tried but it does not work, so instead pxz is recomended)

tar -c -I 'xz -9 -T0' -f archive.tar.xz Dir/

One-liner to create a .tar.xz file with 4 Threads to speed up:

XZ_DEFAULTS="--threads=4"; export XZ_DEFAULTS; tar -cJf Pictures.tar.xz Pictures/

OR:

tar -I pxz -cf Pictures.tar.xz Pictures/

11. SSH - Get ssh connected ports information

From Server:

sudo lsof -i -n | egrep '\<sshd\>'

From client:

sudo lsof -i -n | egrep '\<ssh\>'

12. Find the USED and UNSED space using lsblk:

sudo lsblk -o NAME,SIZE,FSTYPE,MOUNTPOINT,FSUSED,FSUSE%,FSAVAIL /dev/sda /dev/sdb

13. Encrypt/Decrypt files using gpg:

Encrypt:

gpg --symmetric --cipher-algo AES256 <FILE.txt>

Decrypt:

gpg -d FILE.txt.gpg > FILE.txt