Unblock is a tiny utility to make shell pipes behave as if they have unlimited buffering.

a | unblock | b

Generally, Unblock's behavior is not what you want: you want the standard behavior where pipes have a fixed size buffer and slow readers exert backpressure on writers. However, it can sometimes be useful to have an unlimited buffer in user memory.

Here is one scenario where Unblock might be useful. Suppose you have a program slow that produces 5000 lines of output, but does it slowly, perhaps because it's doing lots of computation. Because the output doesn't fit on a screen, you want to use less to view the output. But if you do slow | less, once the pipe buffer fills up, slow gets blocked. If you scroll down in less, you'll need too wait for slow to catch up and produce output. One way you might work around this is to decouple the two processes and make slow fully materialize its output into a file, running slow > out.txt and viewing the results with a less +F out.txt. Unblock makes this kind of workflow easier: slow | unblock | less.

Unblock buffers its input in memory, buffering as much as necessary, and writes it out as fast as the reader can accept it. Note that Unblock's buffer is unlimited in size, so if a writer produces a huge amount of output and the reader is slow, Unblock is going to consume a lot of memory.

Download a binary release: Unblock releases.

Install from source with go get:

go get github.com/anishathalye/unblock

Copyright (c) Anish Athalye ([email protected]). Released under the MIT license. See LICENSE.md for details.