Common Linux Commands

Show directory size

root@mylinux:~/myproject$ du -sh node_modules/
488M    node_modules/

Display amount of free and used memory in the system

root@mylinux:~$ free -h
              total        used        free      shared  buff/cache   available
Mem:           1.9G        195M        1.0G        692K        720M        1.5G
Swap:            0B          0B          0B

Add system wide environment variable

sudo nano /etc/environment

Add a new variable on each line using the syntax: VARNAME=VALUE, reboot to take effect.

Show and set time zone

Show your current time zone:

timedatectl

List available time zones:

timedatectl list-timezones

Change time zone:

sudo timedatectl set-timezone your_time_zone