If the size is omitted,it is one megabyte (1000000).

The system blocksize of 8K (8192) is used; you can override this by using the BLKSIZ environment variable. The code actually writes one null byte every BLKSIZ bytes, which should cause the file to be created rapidly.

createfile 5000000 5MBtest

This generates a 5-megabyte file "5MBtest" filled with null bytes.

createfile 8000000 foo bar

This generates two 8-MB files, "foo" and "bar".

createfile 50000 tmp1 tmp2 25000 tmp3 tmp4

This creates four files: tmp1 and tmp2 will be 50000 bytes; tmp3 and tmp4 will be 25000 bytes.