From ad3403adb72e3457eb76d6b3fc91cf8df3d738ae Mon Sep 17 00:00:00 2001 From: Gabriel Schneider Date: Tue, 29 Sep 2026 09:51:11 -0300 Subject: A shell that cannot start fails Tty and pty/ctl exec with why, before either answers A shell whose exec failed (a script's missing interpreter) was reported started: Tty and pty/ctl exec succeeded, then the pane died. The child now reports a failed chdir or exec through a close-on-exec pipe the parent reads before acknowledging the shell; the host's spawn fails with the reason (`shell not found`, ENOENT), which fails the waiting write. A Tty whose first shell never ran leaves no pane; a terminal restarted by pty/ctl exec keeps its pane. Co-Authored-By: Claude Opus 5.5 --- docs/fs.md | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) (limited to 'docs/fs.md') diff --git a/docs/fs.md b/docs/fs.md index 95c72baa..c3c42d0d 100644 --- a/docs/fs.md +++ b/docs/fs.md @@ -927,8 +927,12 @@ 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: -: no such directory` (ENOENT), and a shell the host cannot start fails -the write with why, as any builtin's failure does. A directory removed +: 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`, ENOENT -- keeping the +terminal; a `Tty` whose shell cannot start fails the same way and leaves +no pane. The host knows before it answers: the child reports a failed exec +through a close-on-exec pipe. A directory removed under a running shell leaves the pane its name (never `... (deleted)`), so an `exec` works there once the directory is back. The size, and `pty/ctl`'s `winsize` read back, is what `winsize C R` last set (R of 1 is taken as 2: a one-row pty loses -- cgit v1.3