When was process substitution first introduced?

Question

I'm curios to know how long process substitution has been around. What shell first had it? When did it get added to other shells?

Answer 1

Process substitution was already in the very first release of ksh88 AFAIK. When it was designed/introduced exactly, we may have to ask David Korn, but it probably doesn't matter, since it probably never came out of Bell labs anyway.

99% of bash features come either from the Bourne shell, the Korn shell, csh, tcsh or zsh. It's always difficult to find out when and where things were introduced especially when considering that many features of ksh were never documented or documented long after they were introduced.

Answer 2

I thought process substitution was introduced in the Korn shell but as to which release (88 or 93) ... ?

Answer 3

The bash hackers wiki has a list of bash features and when they were introduced: http://wiki.bash-hackers.org/scripting/bashchanges

This list does not include process substitution, so it took some further research. According to this article, which references the changelog, version 1.13.5 had working process substitution: http://www.quora.com/Which-version-of-bash-added-the-Process-Substitution-feature

The date on the changelog entry is Sun Feb 23 03:38:59 1992.