More Linux commands

Get file type 

file /etc/hosts
Output first part (10 lines) of the file 
head /etc/hosts
Show first 5 lines 
head -5 /etc/hosts
Output last part (10 lines) of the file 
tail /etc/hosts
Show last 5 lines 
tail -5 /etc/hosts
To watch a file for changes with the tail command pass the -f option 
tail -f /var/log/messages
How long the system has been up 
uptime
Show memory information 
free
Display processes 
ps -A
Show file system disk space usage 
df -h
Pull information about the partitions 
fdisk -l
lsblk
Display processes (q to quit) 
top
htop
To get user which you are logged in 
whoami
id -un
Get more information about the user 
id
Show hostname of the system 
hostname
See the output of command page by page (q to exit) 
hostname --help | less
Set user password 
passwd
Get kernel information 
uname -a
Get/set the date and time 
date
Show last logins that happened on the system 
last
To switch between users - you will be prompted for users password 
su lora
Switch between users by opening a login shell (the full environment of a target user will be set) 
su - lora
Execute commands as root (needs an entry in /etc/sudoers) 
sudo ls /root
Become root 
sudo -i
sudo su -
su -
Login via SSH to another hostname using specified username 
ssh lora@192.168.1.2
Download a file from Internet 
curl http://domain.tld/file.txt -O
wget http://domain.tld/file.txt -O file.txt
Check OS version 
ls /etc/*release*
cat /etc/*release*
Get networking information 
ifconfig
ip a