How to create a file with a given size in Linux?

Question

For testing purposes I have to generate a file of a certain size (to test an upload limit).

What is a command to create a file of a certain size on Linux?

Answer 1

Just to follow up Tom's post, you can use dd to create sparse files as well:

dd if=/dev/zero of=the_file bs=1 count=0 seek=12345

This will create a file with a "hole" in it on most unixes - the data won't actually be written to disk, or take up any space until something other than zero is written into it.