It may be useful for testing purposes, create arbitrary files heavy, the dd command allows you to create file "empty" of a size:

dd if = / dev / zero of = fichier_Ã*_créer bs = 1k count = 1000
This command creates a "vacuum" of a mega!
(1000 blocks of 1K)

Note: you can also replace / dev / zero by / dev / urandom to fill the file with random bits and not zero.