Delegating complex treatments to filters in shell programs (2015)

Re:Delegating complex treatments to filters in shell program... by falsedan on Friday May 12, 2017 @12:22PM (#14325325)

Bash is all about shelling out: it's a shell. I would happily use grep here, and if I had an array:

  printf "%s\0" "$@" | grep -qz needle

> much more performant

I believe that performance-critical code shouldn't be written in bash. I have seen pipelines be much faster than tweaked bash functions, simply because they run in parallel & thus the cost of forking is paid once, up-front.

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Re:Delegating complex treatments to filters in shell program... by jstimpfle on Friday May 12, 2017 @12:53PM (#14325606)

I agree with you. I think we are just speaking about different things.

I was more thinking about the things that happen in a configure script, for example. Not a "hoot loop" like a big grep over millions of lines or something.

There are situations in shell code where the difference between a case-match or string-suffix-replace written in shell and a process spawn matters. Not only because forking a process for one simple string operation is wasteful (cost: about 1ms), but also because of the semantic problems that come with child processes (error handling).

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