Primer: Tips for using Random Test Files

On Mac and Linux, create a random file (
dd if=/dev/urandom of=random-test-file-100m bs=1024k count=100

$ dd if=/dev/urandom of=random-test-file-100m bs=1024k count=100
100+0 records in
100+0 records out
102400000 bytes transferred in 10.143507 secs (10095128 bytes/sec)

This is a random file. You should also use shasum -A 256 and make sure the file you are using for test is what you get back. Do also remember 1024 bytes to a KB… use blocksizes of 1024

On linux, create a fast file (
fallocate -l 100M test-file-100m

This takes less than a second. The file is not good for testing random behaviors with large files as the generated file is huge, but the same bytes repated for 100M.

To check the size of the sample files, you can use human readable format settings (

MacBook-Air:test user$ ls -lSh
total 24
-rw-r–r– 1 user staff 10K Dec 20 19:53 setup.log

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