Change the system language

I want to change both the login window language and the language of the terminal applications.

To change the OS language you go to system prefs/international/languages and move your language to the top of the list. Not all languages will work -- only those 18 listed in the tech specs for OS X.

To change the login window language, try opening Terminal and typing:

sudo "/System/Library/CoreServices/Language Chooser.app/Contents/MacOS/Language Chooser"

As for "terminal applications", you need to explain exactly what you mean. Normal Apple Cocoa apps come with some or all of the normal OS X system languages included, but as for apps made by others or unix apps, it is up to the authors whether anything other than English is possible.

To change the OS language, go to Sys Prefs - International and drag your preferred language to the top of the list. Then reboot.

What do you mean by the "terminal applications"?

/p

Example: I type ls --help and I get the help message in portuguese.

Sorry, no idea whether that is possible. Ask in the Unix forum.

http://discussions.apple.com/forum.jspa?forumID=735