sudo apt-get install gtk-theme-switch
Just for people's info, alot of people come on irc and ask what binary to execute after installing a package. In most cases, the following will be enough info (I'll take gtk-theme-switch2 as an example):
[john@limbo john]$ pacman -Ql gtk-theme-switch2 | grep bin
gtk-theme-switch2 /usr/bin/
gtk-theme-switch2 /usr/bin/switch2
[john@limbo john]$
pacman也得安装