this post was submitted on 16 Jan 2024
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Linux

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Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).

Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.

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[–] faho@lemmy.world 4 points 9 months ago

One big, long-standing issue is that fish can't run builtins, blocks or functions in the background or at the same time.

That means a pipeline like

seq 1 5 | while read -l line
    echo line; sleep 0.1; 
end | while read -l line
    echo line; sleep 0.1
end

will have to wait for the first while loop to complete, which takes 0.5s, and then run the second.

So it takes 0.5s until you get the first output and a full second until you get all of it.

Making this concurrent means you get the first line immediately and all of it in 0.5s.

While this is an egregious example, it makes all builtin | builtin pipelines slower.

Other shells solve this via subshells - they fork off a process for the middle part of the pipeline at least. That has some downsides in that it's annoyingly leaky - you can't set variables or create a background job in those sections and then wait for them outside, because it's a new process and so the outer shell never sees them.