document debug env variable

1 files changed, 12 insertions, 0 deletions

diff --git a/script/deb-systemd-helper b/script/deb-systemd-helper
index 2414c70..1beb750 100755
--- a/script/deb-systemd-helper
+++ b/script/deb-systemd-helper
@@ -53,6 +53,18 @@ systemd unit files. It is specifically NOT intended to be used interactively by
 users. Instead, users should run systemd and use systemctl, or not bother about
 the systemd enabled state in case they are not running systemd.
 
+=head1 ENVIRONMENT
+
+=over 4
+
+=item B<_DEB_SYSTEMD_HELPER_DEBUG>
+
+If you export _DEB_SYSTEMD_HELPER_DEBUG=1, deb-systemd-helper will print debug
+messages to stderr (thus visible in dpkg runs). Please include these when
+filing a bugreport.
+
+=back
+
 =cut
 
 use strict;