Forward and Reverse DNS Lookups

Hostname to IP:
perl -MSocket -lne 'print "$_: ", eval { inet_ntoa inet_aton $_ }' sites.txt
IP to hostname:
perl -MSocket -lne 'print "$_: ", scalar gethostbyaddr( inet_aton( $_ ), AF_INET )' ips.txt

US International Keyboard

To enable typing of international characters with AltGr key while using US layout:
setxkbmap -rules evdev -model evdev -layout us -variant altgr-intl
To make the changes persistant create /etc/X11/xorg.conf.d/10-keyboard-layout.conf file:
Section "InputClass"
        Identifier "keyboard-layout"
        Driver "evdev"
        MatchIsKeyboard "yes"
        Option "XkbLayout"  "us"
        Option "XkbVariant" "altgr-intl"
EndSection
Some useful key combinations:
  • áAltGr+a
  • äAltGr+q
  • čShift+AltGr+.+c
  • ďShift+AltGr+.+d
  • éAltGr+e
  • íAltGr+i
  • ĺAltGr+'+l
  • ľShift+AltGr+.+l
  • ňShift+AltGr+.+n
  • óAltGr+o
  • ôAltGr+6+o
  • ŕAltGr+'+r
  • šShift+AltGr+.+s
  • ťShift+AltGr+.+t
  • úAltGr+u
  • ýAltGr+'+y
  • žShift+AltGr+.+z
  • £Shift+AltGr+4
  • AltGr+5
  • ¥AltGr+-
  • ©AltGr+c
  • °Shift+AltGr+;
  • AltGr+;