Zsh Mailing List Archive
Messages sorted by: Reverse Date, Date, Thread, Author

Re: Where is this =(:) construct documented?

2021-06-11 14:17:08 -0500, Zach Riggle:
> It's insane, cool, and I can't find this documented anywhere.  It
> creates a temporary file that is automatically deleted... but only
> after the line / expression terminates.
> What's more insane is that the temporary file will be auto-populated
> with the output of the =() construct.  Where is THAT documented?


info zsh "Process Substitution"



That's the third form of process substitution.

ksh introduced the first two <(...) and >(...) in the 80s. zsh
added that third form in the 90s.

While A <(B) and A >(B) are IPC mechanisms in that A and B are
started concurrently and connected via a pipe (<(B) and >(B)
expand respectively to the path of the reading of a pipe and
writing end of a pipe, in A =(B), B is started first, its output
collected into a temp file, and the path of that temp file
passed to A when B has finished (and later removed when A


Messages sorted by: Reverse Date, Date, Thread, Author