pty/ctl exec on a command pane is refused: a command pane does not restart

exec on a finished command pane ran its line again, silently, with no header, footer or records. It is now refused, EINVAL, invalid exec: a command pane does not restart.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/fs.md b/docs/fs.md
index eab1b00d..6bf30212 100644
--- a/docs/fs.md
+++ b/docs/fs.md
@@ -993,7 +993,9 @@ which is also when the third field of `pty/status` reads 1. `pty/status` is
 one line, three right-aligned fields and a newline: the pty's columns and
 rows, then busy (0 or 1). `pty/ctl` takes `winsize C R`, `sig
 INT|TERM|HUP|QUIT|KILL` and `exec`, which starts the pane's shell again in
-its directory: one that is gone is refused before anything runs, `exec:
+its directory (a command pane's child is its command, which does not
+restart: `exec` there is refused, EINVAL, `a command pane does not
+restart`): one that is gone is refused before anything runs, `exec:
 <dir>: no such directory` (ENOENT), and a shell the host cannot start (not
 there, not executable, a script whose interpreter is not there) fails the
 write with why -- `shell: shell not found`, or `shell: interpreter