This was requested in https://github.com/systemd/systemd/issues/42333.
Indeed, this integration is using three levels of systemd magick, so
doing this correctly is not obvious. Let's include specific instructions
to help people for whom this integration is causing problems.
UAPI.15 requires:
* No C0 Control Characters (`\x00-\x1f`)
* No DEL character (`\x7f`)
The following would be nice, but requires a `sed` implementation that is
aware of UTF-8: `-e $'y/\x00-\x1f\x7f/␀-␟␡/'`.
References:
[0] https://uapi-group.org/specifications/specs/osc_context/#general-syntax
Bash does not provide an easy way to discern if an exit status came from
a signal, or was a legitimate non-zero exit (i.e. a failure). It can be
done, by using job control or by invoking another program; however, such
approaches require modifying the command entered by a user and are, thus,
invasive and risky.
Since an exit status of 129 on a command could either indicate it exited
cleanly with `exit(129)` or was interrupted by `SIGHUP`, the osc context
should report both possibilities, to acknowledge our uncertainty. Given
we have no idea what happened, besides an unsuccessful exit, the exit is
described as `exit=failure`.
Moreover, discerning between an `interrupt` and a `crash` with a command
likely involves categorizing every signal. It is fairly obvious `SIGINT`
is an interrupt and also obvious, IMO, that `SIGSEGV` is a crash. Avoid
the complication (and potential disagreements) by using the encompassing,
generic value — one that remains true if no signal occurred.
References:
[0] https://stackoverflow.com/a/66431355
Symlinks to files inside sysconfdir are now only installed if
ìnstall_sysconfdir=true (which is the default).
If sshconfdir,sshdconfdir,shellprofiledir are not inside sysconfdir and
install_sysconfidr=false, these symlinks are still installed to the
configured directory.
Let's do the check early and skip most of the file if appropriate. Also, treat
missing $TERM same as "dumb". We're almost certainly at a dump terminal in that
case.
In https://github.com/systemd/systemd/issues/39114 users are reporting
that our script overrides PROMPT_COMMAND that they had. After looking
at /etc/bashrc in Fedora, I see that it only sets PROMPT_COMMAND if
[ -z "$PROMPT_COMMAND" ]. Let's adjust the script so this continues to
work.
Fixes https://github.com/systemd/systemd/issues/39114.
(This is a bit of a stretch. 39114 was originally about SecureCRT,
but that was resolved in SecureCRT. But there was a lot of dicussion
about the prompt being overriden, which this commit should fix.)
While we can safely assume that `/proc/sys/kernel/random/boot_id`
exists, the same can't be said for `/etc/machine-id` in environments
where systemd is installed, but not running. An example would be OCI
containers like with the official Arch Linux image, see [0].
Without this check the prompt would constantly output `/etc/machine-id:
no such file or directory` with the OSC events introduced in dadbb34
(v258).
[0] https://gitlab.archlinux.org/archlinux/archlinux-docker/-/issues/107
Now our baseline of meson is 0.62, hence install_symlink() can be used.
Note, install_symlink() implies install_emptydir() for specified
install_dir. Hence, this also drops several unnecessary
install_emptydir() calls.
Note, the function currently does not support 'relative' and 'force' flags,
so several 'ln -frsT' inline calls cannot be replaced.
If - for whatever reason - a script uses set -u (nounset) and includes
/etc/profile.d/70-systemd-shell-extra.sh (e.g. transitively via
/etc/profile) the script would fail with:
/etc/profile.d/70-systemd-shell-extra.sh: line 15: SHELL_PROMPT_PREFIX: unbound variable
For example:
$ cat > foo.sh <<EOF
#!/bin/sh
set -u
source /etc/profile
EOF
$ chmod 700 foo.sh
$ ./foo.sh
/etc/profile.d/70-systemd-shell-extra.sh: line 15: SHELL_PROMPT_PREFIX: unbound variable
Fix this by using shell parameter substitution[^1] (which is a POSIX
shell concept) to set the $SHELL_* variables to the empty string if
undefined.
[^1]: https://pubs.opengroup.org/onlinepubs/9699919799.2018edition/utilities/V3_chap02.html
