Can I safely remove all the files in /tmp?

I want to make free space on my computer, and Baobab tells me /tmp is 8 Gio large. Can I delete all the files in /tmp safely? Do I have to close some programs first?

Additionally, why is this directory so big? Though my /etc/defautl/rcS indicates TMPTIME=0?

In Unix, deleting a file removes a reference to it from its parent directory (this actually is called "unlinking").

The actual file data is only deleted when it's not referenced from any directory (a file can have multiple so-called hardlinks) and it's not open by any program.

So yes, deleting files from /tmp should not crash programs which potentially keep those files open. On the other hand, the actual disk space won't be freed until the program closes the already-deleted file.