Linux Sytem Administration Tips

Privileges

sudo command – run command as root

sudo -s – open a root shell

sudo -s -u user – open a shell as user

sudo -k – forget sudo passwords

gksudo command – visual sudo dialog (GNOME)

kdesudo command – visual sudo dialog (KDE)

sudo visudo – edit /etc/sudoers

gksudo nautilus – root file manager (GNOME)

kdesudo konqueror – root file manager (KDE)

passwd – change your password

Display

sudo /etc/init.d/gdm restart – restart X and

return to login (GNOME)

sudo /etc/init.d/kdm restart – restart X and

return to login (KDE)

(file) /etc/X11/xorg.conf – display

configuration

sudo dexconf – reset xorg.conf configuration

Ctrl+Alt+Bksp – restart X display if frozen

Ctrl+Alt+FN – switch to tty N

Ctrl+Alt+F7 – switch back to X display

Special Packages:

ubuntu-desktop – standard Ubuntu environme nt

kubuntu-desktop – KDE desktop

xubuntu-desktop – XFCE desktop

ubuntu-minimal – core Ubuntu utilities

ubuntu-standard – standard Ubuntu utilities

ubuntu-restricted-extras – non-free, but useful

kubuntu-restricted-extras – KDE of the above

xubuntu-restricted-extras – XFCE of the above

build-essential – packages used to compile

programs

linux-image-generic – latest generic kernel

image

linux-headers-generic – latest build headers

Package Management1

apt-get update – refresh available updates

apt-get upgrade – upgrade all packages

apt-get dist-upgrade – upgrade with package

replacements; upgrade Ubuntu version

apt-get install pkg – install pkg

apt-get purge pkg – uninstall pkg

apt-get autoremove – remove obsolete packages

apt-get -f install – try to fix broken packages

dpkg –configure -a – try to fix broken

packages

dpkg -i pkg.deb – install file pkg.deb

(file) /etc/apt/sources.list – APT repository

list

System

Recovery – Type the phrase “REISUB” while

holding down Alt and SysRq (PrintScrn) with

about 1 second between each letter. Your system

will reboot.

lsb_release -a – get Ubuntu version

uname -r – get kernel version

uname -a – get all kernel information

Application Names

nautilus – file manager (GNOME)

dolphin – file manager (KDE)

konqueror – web browser (KDE)

kate – text editor (KDE)

gedit – text editor (GNOME)

Firewall1

ufw enable – turn on the firewall

ufw disable – turn off the firewall

ufw default allow – allow all connections by

default

ufw default deny – drop all connections by

default

ufw status – current status and rules

ufw allow port – allow traffic on port

ufw deny port – block port

ufw deny from ip – block ip adress

Network

ifconfig – show network information

iwconfig – show wireless information

sudo iwlist scan – scan for wireless networks

sudo /etc/init.d/networking restart – reset

network for manual configurations

(file) /etc/network/interfaces – manual

configuration

ifup interface – bring interface online

ifdown interface – disable interface