from Hacker News

Unix Philosophy with an Example

by aaossa on 11/28/22, 8:28 PM with 1 comments

• by Someone on 11/28/22, 9:31 PM

  The overhead of the Unix philosophy for such simple steps is gigantic. The example (seq 1 6 | shuf | head -n 1) creates three processes, pipes six strings between the first and the second, and one of them on to the third, and likely calls a RNG six times.

  That’s why shuf isn’t a “program that does one thing and does it well”, and allows for a few simple optimization steps:

  - use the “-i” option to get rid of the seq process:

    shuf -i1-6 | head
  

  - use the “-n” option to get rid of the head process:

    shuf -i1-6 -n 1
  

  One process, no pipes, but it probably (I didn’t check the source code) still creates those six strings, and makes those 6 RNG calls.

  Even that wastes time and memory. If you’re simulating a large die (say a 10,000-sided one) you may be better of running an awk or Perl script that calls a RNG once.