create-a-file-of-any-size.mdx

category	contributors	created	tags	title	updated
Tip	dylankenneally	2021-03-19	macOS	Create a file of any size	2022-09-08

Sometimes we need big files for testing purposes, without any concern for the files' content. For example, when testing uploads, downloads & responding to changes in network performance, we are likely to want files of various sizes.

macOS comes with a helpful utility command to create a file of any size over 512 bytes called mkfile:

$ mkfile FILE_SIZE FILE_NAME

In the FILE_SIZE option, we can optionally use a suffixes to note the unit of the value b - bytes (the deafult), k - kilobytes, m - megabytes or g - gigabytes.

For example, the following command produces an empty two gigabyte file named big-file.ext:

$ mkfile 2g big-file.ext

Note the following multiplication factors are applied to the FILE_SIZE value:

Unit	Factor	Examples
b	512	For 512 bytes: 1b, for 1kb (1024 bytes): 2b
k	1024	For 1kb (1024 bytes): 1k, for 1mb (1,048,576 bytes): 1024k
m	1048576	For 1mb (1,048,576 bytes): 1m, for 1gb (1,073,741,824 bytes): 1024m
g	1073741824	For 1mb (1,073,741,824 bytes): 1g, for 2gb (2,147,483,648 bytes): 1g

See the man page for mkfile for more information.

$ man mkfile

See also

• Create a big file on Linux