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Comment by zerojames | Hacker News Reader

Unfortunately, that command doesn't work on macOS (`/usr/bin/man: illegal option -- l`). I tried to get a one-liner with piping working on my Mac but I always ran into errors. The -l flag doesn't exist in the macOS man implementation (I consulted the man page; meta!).

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The `-l` can be skipped (probably because there are `/`s in man's argument):

  curl -sL -H "Accept: text/roff" https://jamesg.blog/2024/02/28/programming-projects/ | man /dev/stdin

(which still doesn't work on mac)

This still doesn’t work for me on macOS, perhaps a difference in how /dev/stdin is implemented?

Fortunately, macOS has ZSH as the default shell so the following does work:

  man =(curl -sL -H "Accept: text/roff" https://jamesg.blog/2024/02/28/programming-projects/)

Maybe 'man <(curl -sL -H "Accept: text/roff" https://jamesg.blog/2024/02/28/programming-projects/)' works then?

Nope

This doesn’t work because it’s equivalent to piping stdout from curl into stdin for man.

It's not, that would be `man <<< "$(curl ...)" `. `man <(curl ...)` is a slightly different version of the process substitution[1] from your comment - `man =(curl ...)`.

[1] https://zsh.sourceforge.io/Doc/Release/Expansion.html#Proces...

You’re right, it isn’t quite the same as piping.

man <(curl ...) ends up working on Linux but for whatever reason still yields an error on macOS:

  No manual entry for /dev/fd/11

  curl -sL -H "Accept: text/roff" https://jamesg.blog/2024/02/28/programming-projects/ | mandoc -a

works on macOS (and should also work on (Free|Net|Open)BSD, which ship similar man toolchains).

It's actually process substitution: https://www.gnu.org/software/bash/manual/html_node/Process-S...

It's essentially running the process in another shell and sending its output to a tempfile. The name of that file is then substituted in the original command. So, in theory, equivalent to `inner > /tmp/file; outer /tmp/file`. This works with programs that don't read from stdin, or need two or more inputs, for example.

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