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systemd/profile.d/70-systemd-shell-extra.sh
Tobias Klauser 12e33d332b profile.d: don't bail if $SHELL_* variables are unset
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
2024-12-11 18:33:41 +00:00

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# shellcheck shell=sh
# This file is part of systemd.
#
# systemd is free software; you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or
# (at your option) any later version.
# Import the additional shell prompt prefix and suffix strings into $PS1, and
# show the shell welcome string. These can be provisioned as system or service
# credentials shell.prompt.prefix, shell.prompt.suffix and shell.welcome, and
# are propagated into these environment variables by pam_systemd(8).
if [ -n "${SHELL_PROMPT_PREFIX-}" ]; then
PS1="$SHELL_PROMPT_PREFIX$PS1"
fi
if [ -n "${SHELL_PROMPT_SUFFIX-}" ]; then
PS1="$PS1$SHELL_PROMPT_SUFFIX"
fi
if [ -n "${SHELL_WELCOME-}" ]; then
printf '%b\n' "$SHELL_WELCOME"
fi