Linux Cheat Sheet

Check Kernel Version

uname -a

Check IP

ifconfig

ip addr show

Check disk space

df -ah

Work with services

service <service-name> status
systemctl status <service-name>

Check folder size

Disk use

du -sh <directory>

Check for open ports

netstat

Check CPU usage

ps aux | grep <process-name>

top

Mounting

mount /dev/sda2 /mnt

Check for existing

mounts

Auto mount in file

/etc/fstab

Manpages

Manual pages

man <command>

Permissions

Show permissions

stat file.txt

Change permissions

# denies file read for others
chmod o-r file.txt
# read for user, read for group, deny access to others
chmod u=r,g=r,o= file.txt

File Transformation

Use jq to transform JSON files.

cat logs.json | jq '.["@timestamp"] + "   " + .message' > logs.txt

Transforms extracts timestamp and message from JSON objects and prints them into logs.txt.