Do not change your '/usr' permissions.

Yours sincerely,
A linux user who's been fucked up(twice) doing this because he wanted to install a fucking font.

Oooooh mannn chillz down my spine , just a few hours ago i was trying to edit theme files there. Am not much into linux so got scared and left the things as it is. Thanks for this rant !)

sudo cp random-font.ttf /usr/share/fonts/truetype/

@rEaL-jAsE hahahahahahashutuphahaha

@rEaL-jAsE I'd just like to interject for a moment. What you're referring to as Linux, is in fact, GNU/Linux, or as I've recently taken to calling it, GNU plus Linux. Linux is not an operating system unto itself, but rather another free component of a fully functioning GNU system made useful by the GNU corelibs, shell utilities and vital system components comprising a full OS as defined by POSIX.