Finding commands
The apropos command can be useful to find commands related to a keyword. You can then use man to get details of the specific command.
For example, apropos processes lists the commands related to process management.
apropos keyword
man command
Package management
dnf install [-y]package...
dnf install -f -reinstall package... # fix a broken package
dnf search package...
dnf update # updates package lists
dnf upgrade # upgrade packages
dnf remove package...
dnf purge package... # removes the package and its config files
Networking
ip addr show # show interfaces and wetwork addreses
ss -l # shows listening sockets
System information
uname -a # shows basic system info
df -h # shows disk space utilisation
free -m # displays free memory in Mb
Service management
sudo systemctl star\|stop|status|restart|reload service
Viewing the system logs
journalctl -f
journalctl -u unit
Managing cron jobs
crontab -e # edit cron jobs
crontab -l # lists cron jobs