Linux
=====

Commands
--------

List all files in current directory

**ls**

List all files in current directory including hidden items

**ls -a**

List all files in current directory with details

**ls -l**

List all txt files in current directory

**ls \*.txt**

Change the current directory

cd directoryname

Go up 1 level

cd ..

Copy a file or folder

**cp oldfile.txt newfile.txt**

Note that to copy the contents of a folder you need to specify the -R flag

Move/Rename a file or folder

**mv oldfile.txt newfile.txt**

Delete a file without confirmation prompt

**rm filename.txt**

Delete a file with confirmation prompt

**rm -i filename.txt**

Delete a directory

**rmdir directorytodelete**

Note that this command will only delete the directory itself and not the contents of the directory

Delete the contents of a directory with confirmation prompt

rm -ir \[foldername\]

mkdir

List all users

**getent passwd**

https://linuxize.com/post/how-to-list-users-in-linux/

Mounting Volume

Syntax:

mount -t type device dir

sudo mount -o remount,rw /media/linux/OLD\_PC� /media/linux/OLD\_PC

List drives currently connected to the system

sudo fdisk -l

or

sudo blkid

or

lsblk

or

sudo parted -l

List drives by UUID

ls -l /dev/disk/by-uuid

List mounted drives

cat /proc/mounts

or

mount

or

df -aTh

or

findmnt

https://www.rapidtables.com/code/linux/cp.html

Repair Damaged File System
--------------------------

1.  Boot the machine using external live media
    
2.  Use the follow command to list filesystem partitions
    

**sudo fdisk -l**

1.  Use the following command to unmount the partition that needs to be repaired (it probably will already be unmounted but it is good to do this step to be certain because running this command on a mounted partition could cause other issues)
    

**sudo umount /dev/sda1**

1.  Use the following command to repair the file system
    

**sudo fsck -p /dev/sda1**

https://www.linuxshelltips.com/repair-ubuntu-filesystem/

https://www.tecmint.com/fsck-repair-file-system-errors-in-linux/

Reset Ubuntu Admin User Password
--------------------------------

Option 1:

1.  Turn on the machine and hold the Shift key to load the GRUB Bootloader menu (if it doesn�t appear automatically)
    
2.  Choose the recovery mode option
    
3.  Choose the �Root � Drop to root shell prompt� option
    
4.  Remount the root partition with write access
    

**mount -rw -o remount /**

1.  List all user accounts
    

**ls /home**

1.  Reset the password using the following command, substituting �username� with the username of the account to reset the password of (if you get �Authentication token manipulation error�, it means that the file system is mounted with read only access)
    

**passwd username**

1.  Exit the terminal
    

**exit**

Option 2:

1.  Turn on the machine and hold the Shift key to load the GRUB Bootloader menu (if it doesn�t appear automatically)
    
2.  Press �E� to edit the command
    
3.  Find the line starting with �**linux**� and change the �**ro**� in that line to �**rw**� and append �**init=/bin/bash**� at the end
    
4.  Press Ctrl + X to boot
    
5.  List all user accounts
    

**ls /home**

1.  Reset the password using the following command, substituting �username� with the username of the account to reset the password of (if you get �Authentication token manipulation error�, it means that the file system is mounted with read only access)
    

**passwd username**

1.  Shut down the machine
    

**sudo halt**

https://www.hiroom2.com/2016/05/20/ubuntu-16-04-reset-forgotten-password/

https://www.hiroom2.com/2016/05/20/ubuntu-16-04-fix-mojibake-on-recovery-mode/

https://itsfoss.com/how-to-hack-ubuntu-password/

[https://www.tecmint.com/reset-forgotten-root-password-in-debian/](https://www.tecmint.com/reset-forgotten-root-password-in-debian/)

[https://monovm.com/blog/how-to-change-linux-password/](https://monovm.com/blog/how-to-change-linux-password/)

Change VT (Virtual Terminal)

Most distributions support switching to a different VT with Alt+F1 , Alt+F2, etc

A graphical environment (X-window) is just one of those VTs, often 6th or 7th.

To switch from an X-Window session to another VT you need to press Alt+Ctrl+F1, e t.c. (unless this is forbidden through novtswitch option)

Grub boot loader stuff

Edit the file /etc/default/grub

**sudo gedit /etc/default/grub**

Open a terminal with Ctrl + Alt + T and type **sudo update-grub** to apply the changes you just made

You can use an application called Grub Customizer

sudo add-apt-repository ppa:danielrichter2007/grub-customizer

sudo apt-get update

sudo apt-get install grub-customizer