Comment by arjie
15 hours ago
Redirects are fun but there are way more than I actually routinely use. One thing I do is the file redirects.
diff <(seq 1 20) <(seq 1 10)
I do that with diff <(xxd -r file.bin) <(xxd -r otherfile.bin) sometimes when I should expect things to line up and want to see where things break.
It's a shame that unix tools don't support file descriptors better. The ability to pass a file (or stream, or socket etc) directly into a process is so powerful, but few commands actually support being used this way and require filenames (or hostnames, etc) instead. Shell is so limited in this regard too.
It would be great to be able to open a socket in bash[^1] and pass it to another program to read/write from without having an extra socat process and pipes running (and the buffering, odd flush behaviour, etc.). It would be great if programs expected to receive input file arguments as open fds, rather than providing filenames and having the process open them itself. Sandboxing would be trivial, as would understanding the inputs and outputs of any program.
It's frustrating to me because the underlying unix system supports this so well, it's just the conventions of userspace that get in the way.
[^1]: I know about /dev/tcp, but it's very limited.
Process substitution and calling it file redirect is a bit misleading because it is implemented with named pipes which becomes relevant when the command tries to seek in them which then fails.
Also the reason why Zsh has an additional =(command) construct which uses temporary files instead.