Preserve empty pane titles during save and restore - #581
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When pane_title is empty, the save file contains consecutive tab
delimiters. Bash's IFS=$'\t' read collapses these (POSIX whitespace
IFS behavior), shifting every field after pane_title one position
left. This puts pane_active into the dir field, causing panes to
restore in the wrong directory.
Use tmux conditional format #{?pane_title,#{pane_title},_} to
guarantee a non-empty field, outputting "_" for untitled panes.
Fixes tmux-plugins#437
Use the colon guard proposed in tmux-plugins#570 and retain the Docker regression coverage. Co-authored-by: Mateusz Kozlowski <kooziu@gmail.com>
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When pane_title is empty, the tab-delimited save format emits adjacent
tabs. Tab is an IFS-whitespace character, so the `IFS=$d read ...` loops
in dump_panes (save.sh) and restore_pane (restore.sh) collapse the empty
field and shift every later value left by one. dir is then read from the
pane_active column ("1"), remove_first_char reduces it to "", and restore
runs `tmux split-window -c ""`, which falls back to $HOME. Only panes
whose title was empty lose their working directory, which is why this
stays hidden for most users.
Give pane_title the same leading ':' guard already used for the other
optional fields (window_flags, pane_current_path, window_name,
full_command) and strip it back off during restore. The field is never
empty on disk, so it cannot collapse, and a genuinely empty title is
still restored as empty.
The awk parse sites in restore.sh are unaffected: awk with FS="\t" does
not collapse empty fields, and the field count is unchanged.
This is the lossless approach proposed by @mtkozlowski in
tmux-plugins#570 and carried forward in tmux-plugins#581.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
dainis
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dump_panes() re-reads its own tab-delimited record with `IFS=$'\t' read`.
Tab is IFS whitespace, so an empty field collapses instead of being
preserved. Every field that can be empty is emitted with a protective ":"
prefix except pane_title, so a pane with no title shifts the record left
by one: pane_current_path lands in the title slot, pane_active ("0"/"1")
lands in the dir slot, and the full command is lost.
Effects on restore: `split-window -c ""` falls back to the session default
(panes reopen in $HOME), and restore_all_pane_processes() drops the line
via its `$11 !~ "^:$"` filter, so @resurrect-processes never matches.
Claude Code triggers this routinely -- it clears the pane title on exit.
Any program emitting OSC 2 with an empty string does the same.
Guard pane_title like the other nullable fields and strip the guard on
restore. Identical to upstream PR tmux-plugins#582 (closed as a duplicate of tmux-plugins#581);
see also tmux-plugins#520, tmux-plugins#536, tmux-plugins#564 and the closed tmux-plugins#570. Upstream has merged
nothing since 2023-03.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
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Summary
pane_titlewith the same leading:used for other optionalsnapshot fields;
title and distinct non-empty titles;
When
pane_titleis empty, the current format emits adjacent tabs. Bashtreats tab as IFS whitespace and collapses that empty field, shifting every
later value left. Restore then reads
pane_activeas the directory and opensthe pane in
$HOMEinstead of its saved working directory.The colon guard makes the field non-empty on disk while still restoring the
original empty value.
Attribution
This uses the lossless approach proposed by @mtkozlowski in #570. That PR was
closed before maintainer review; its author is credited in the implementation
commit. This PR retains that idea and adds automated save/restore regression
coverage in an isolated environment.
Test environment
The Docker runner has no host mounts or network access, runs as a non-root
user with a read-only root filesystem, and verifies exact container ownership
before cleanup. The pinned environment uses Ubuntu 24.04, tmux 3.4, Bash, and
a 200-by-50 pseudo-terminal.
Verification