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macOS command-line tools you might not know about

(saurabhs.org)
2039 points Gadiguibou | 2 comments | 27 Jun 23 12:08 UTC | HN request time: 0s | source
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klausa ◴[27 Jun 23 12:42 UTC] No.36491947[source]▶
`pbcopy` and `pbpaste` are one of my most-loved in the list.

Dealing with some minified json, switching to iTerm, doing `pbpaste | json_pp | pbcopy` and having a clean output is _so_ nice.

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omginternets ◴[27 Jun 23 13:16 UTC] No.36492265[source]▶
If I had a nickel for each `cat foo.json | jq | pbcopy`, I'd be a rich man :)
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maleldil ◴[27 Jun 23 13:58 UTC] No.36492862[source]▶
That's a useless use of cat. You can use `jq . foo.json | pbcopy` or `jq < foo.json | pbcopy`.
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nicky0 ◴[27 Jun 23 14:17 UTC] No.36493144[source]▶
In what way do you see those alternatives as superior?
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paulddraper ◴[27 Jun 23 14:30 UTC] No.36493372[source]▶
They avoid an unnecessary invocation of the cat executable.

Instead, they open a file descriptor and pass that.

Tiny difference but there you go.

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1. adrianmonk ◴[27 Jun 23 15:04 UTC] No.36493906[source]▶
Not just that, but also all the bytes have to go through an extra pipe. Presumably they're copied an extra time because of this.

When you run "cmd < file", the command reads from stdin, which pulls directly from the file. When you do "cat file | cmd", "cat" opens the file, reads from there, and writes to a pipe. Then "cmd" reads from its stdin, which is a pipe.

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2. chlorion ◴[28 Jun 23 00:56 UTC] No.36500885[source]▶
GNU cat will use the copy_file_range syscall when possible!

copy_file_range allows a user land program to copy data between two files without doing any user space work. Instead of reading data into a buffer and writing it back out to the destination, the kernel will somehow manage to move the data for you.

I think this will prevent any extra copies from occurring in situations where it can be used.

https://man.archlinux.org/man/copy_file_range.2

https://git.savannah.gnu.org/cgit/coreutils.git/tree/src/cat...