[kazinator]

I see in the readline sources that it was added in 2021. (The git history of Chet Ramey's repositories is horrible; he just adds big patch bombs with no individual commits.)

I independently conceived the feature in 2015. I had not seen it anywhere before that, nor have I seen it since!

  commit 51322f6c66d153d2f008a227c5e517f6fb34dbab
  Author: Kaz Kylheku <[e-mail]>
  Date:   Thu Dec 31 05:30:46 2015 -0800

    linenoise: submit and stay in history.

I see the readline source code gives credit to copying this feature from the Korn shell. In misc.c there is a comment:

  /* The equivalent of the Korn shell C-o operate-and-get-next-history-line
     editing command. */

(Where would Bash imagination be without Korn.)

I see in the ksh93 sources that this appeared in or before 2012. (Again, patch bomb wall.)

[kragen]

i've definitely been using this feature in bash since before 02021, probably before 02012