View source for Useful Linux Command Line Stuff

==Networking==
====Get the IP address of all interfaces====
<code>networkctl status</code>


====   ====
<code>hostname -I</code>

====Display all IP addresses of the host====
<code>ip link set <interface> up</code>
<code>ip link set <interface> down</code>

====Enable/disable interface====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

====   ====
<code>   </code>

========
*

* - 
*
*Manage firewall rules
**enable firewall: sudo ufw enable
**list rules: sudo ufw status
**allow port: sudo ufw allow <port>
**deny port: sudo ufw deny <port>
*Connect remotely through SSH
**ssh <user>@<host IP>


Packages
Search for packages
apt search <string>
snap find <string>
List available updates
apt list --upgradable
Apply all available updates
sudo apt update && sudo apt upgrade
Install from the Ubuntu archive:
sudo apt install <package>
Install from the snap store:
sudo snap install <package>
Which package provides this file?
sudo apt install apt-file
sudo apt-file update
apt-file <filename or command>

Files
List files
ls
List files with permissions and dates
ls -al
Common file operations
create empty: touch <filename>
create with content: echo "<content>" > <filename>
append content: echo "<content>" >> <filename>
display a text file: cat <file>
copy: cp <file> <target filename>
move/rename: mv <file> <target directory/filename>
delete: rm <file>
Create a directory
mkdir <directory>
Create directories recursively
mkdir -p <directory1>/<directory2>
Delete a directory recursively
rm -r <directory>
Quick file search
locate <q>
Search string in file
grep <string> <filename>
Search string recursively in
directory
grep -Iris <string> <directory>
Find files modified in the last n minutes
find <directory> -mmin -<n> -type f
eg. find . -mmin -5 -type f
Show only the nth column
col<n> “<separator>” <filename>
eg. col2 “,” foo.csv
Display file paginated
less <filename>
Display first n lines
head -n <n> <filename>
Display last n lines
tail -n <n> <filename>
Follow file content as it increases
tail -f <filename>
Pack a directory into an archive
zip: zip -r <target> <source dir>
tar.gz: tar cvzf <target>.tar.gz <source dir>
Unpack an archive
zip: unzip <zip file>
tar.gz: tar xf <tar.gz file>
Copy file to remote server
scp <filename> <user@server>:<destination>
eg. scp config.yaml admin@192.0.0.0:/config
Copy directory recursively
from remote server
scp -r <user@server>:<source> <destination>
eg. scp -r admin@192.0.0.0:/config /tmp

Security
Show which users are logged in
w
Get password expiration date for
<user>
chage -l <user>
Set password expiration
date for <user>
sudo chage <user>
Lock a user account
sudo passwd -l <user>
Unlock a user account
sudo passwd -u <user>
List open ports and associated
processes
sudo netstat -tulpn

Automatically detect and ban
abusive IP addresses
sudo apt install fail2ban
Show banned IP addresses
sudo fail2ban-client status
sudo fail2ban-client status <jail>
Get the support status for installed
packages
ubuntu-support-status
Enable kernel live patching
sudo snap install canonical-livepatch
sudo canonical-livepatch enable <token>
Visit ubuntu.com/livepatch to get a
free token for up to 3 machines.



System
Display kernel version
uname -r
Get disk usage
df -h
Get memory usage
cat /proc/meminfo
Get system time
timedatectl status
Set system timezone
timedatectl list-timezones
sudo timedatectl set-timezone <zone>
Get all running services
systemctl --state running
Start or stop a service
service <service> start/stop
Monitor new logs for a service
journalctl -u <service> --since now -f

System
Display kernel version
uname -r
Get disk usage
df -h
Get memory usage
cat /proc/meminfo
Get system time
timedatectl status
Set system timezone
timedatectl list-timezones
sudo timedatectl set-timezone <zone>
Get all running services
systemctl --state running
Start or stop a service
service <service> start/stop
Monitor new logs for a service
journalctl -u <service> --since now -f


Kubernetes and containers
Install MicroK8s and list available add-ons
sudo snap install microk8s --classic
microk8s.status --wait-ready
Enable a MicroK8s add-on
microk8s.enable <service>
View MicroK8s nodes and running services
microk8s.kubectl get nodes
microk8s.kubectl get services
More MicroK8s help at microk8s.io/docs
Launch a LXD container
lxd init
lxc launch ubuntu:18.04 <container name>
Or another distro
lxc launch images:centos/8/amd64
<container name>
Get a shell inside a LXD container
lxc exec <name> -- /bin/bash
Push a file to a LXD container
lxc file push <filename>
<container name>/<path>
Pull a file from a LXD container
lxc file pull <destination>
<container name>/<file path>
More LXD help at linuxcontainers.org/lxd

Virtualisation
Install Multipass and launch
an Ubuntu VM
sudo snap install multipass --classic
multipass launch <image> --name <VM name>
Omitting <image> will launch a VM with
the latest Ubuntu LTS
Find available images
multipass find

List existing VMs
multipass list
Get a shell inside a VM
multipass shell <VM name>
More Multipass help at
discourse.ubuntu.com

OpenStack
Install OpenStack and launch
an instance
sudo snap install microstack --classic
sudo microstack.init
microstack.launch
The Horizon dashboard is available at 10.20.20.1
Default credentials: admin / keystone
More MicroStack help at microstack.run/docs