<(command) in fish

[theScrabi]

Hello in bash there is this construct existing <( ). The stdout of the command inside the brackets is redirected, and a file descriptor is returned:

$ echo <(echo "hallo welt")
/dev/fd/63

So You can write constructs like this:

$ cat <(echo "hallo welt")
hallo welt

Is something like this possible with fish?

[faho]

Fish has the psub command that writes its input to a file and prints the name of that file.

So you'd do

cat (echo "Hallo Welt" | psub)

See the documentation for psub.

[theScrabi]

That is cool :D, but it's a file and no pipe right?

[faho]

Short answer: Yes.

Longer answer: By default, yes, but psub technically supports a flag to use a fifo instead. Only that has some issues so I wouldn't currently recommend using it (unless you can guarantee that your output will be smaller than the pipe buffer) - see #1040.

Any reason you want a pipe?

[theScrabi]

I see.

[theScrabi]

A pipe uses kernel buffer which

1. Is faster
2. May use up write cycles on an ssd
3. When you try to pass passwords or keys /tmp might be unsave