Recommend drop-ins over modifications to the main config file

As discussed in https://github.com/systemd/systemd/pull/18347.

15 files changed, 122 insertions, 106 deletions

diff --git a/man/standard-conf.xml b/man/standard-conf.xml
index edb7887b4f..f02b9b0594 100644
--- a/man/standard-conf.xml
+++ b/man/standard-conf.xml
@@ -44,8 +44,9 @@
     <para>The default configuration is set during compilation, so configuration is only needed when it is
     necessary to deviate from those defaults. Initially, the main configuration file in
     <filename>/etc/systemd/</filename> contains commented out entries showing the defaults as a guide to the
-    administrator. Local overrides can be created by editing this file or by creating drop-ins, see below.
-    </para>
+    administrator. Local overrides can be created by editing this file or by creating drop-ins, as described
+    below. Using drop-ins for local configuration is recommended over modifications to the main configuration
+    file.</para>
 
     <para>In addition to the "main" configuration file, drop-in configuration snippets are read from
     <filename>/usr/lib/systemd/*.conf.d/</filename>, <filename>/usr/local/lib/systemd/*.conf.d/</filename>,
diff --git a/src/core/system.conf.in b/src/core/system.conf.in
index 40bb548887..eecaff9f27 100644
--- a/src/core/system.conf.in
+++ b/src/core/system.conf.in
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See systemd-system.conf(5) for details.
 
diff --git a/src/core/user.conf.in b/src/core/user.conf.in
index bbe06319c9..d3887e1c87 100644
--- a/src/core/user.conf.in
+++ b/src/core/user.conf.in
@@ -1,14 +1,16 @@
 #  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.
+#  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.
 #
-# You can override the directives in this file by creating files in
-# /etc/systemd/user.conf.d/*.conf.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See systemd-user.conf(5) for details
+# See systemd-user.conf(5) for details.
 
 [Manager]
 #LogLevel=info
diff --git a/src/coredump/coredump.conf b/src/coredump/coredump.conf
index c2f0643e03..738c45bed2 100644
--- a/src/coredump/coredump.conf
+++ b/src/coredump/coredump.conf
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See coredump.conf(5) for details.
 
diff --git a/src/home/homed.conf b/src/home/homed.conf
index 1b5dbedabd..86b6266895 100644
--- a/src/home/homed.conf
+++ b/src/home/homed.conf
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See homed.conf(5) for details
+# See homed.conf(5) for details.
 
 [Home]
 #DefaultStorage=
diff --git a/src/journal-remote/journal-remote.conf.in b/src/journal-remote/journal-remote.conf.in
index edc3abab4b..1e4c3b9710 100644
--- a/src/journal-remote/journal-remote.conf.in
+++ b/src/journal-remote/journal-remote.conf.in
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See journal-remote.conf(5) for details
+# See journal-remote.conf(5) for details.
 
 [Remote]
 # Seal=false
diff --git a/src/journal-remote/journal-upload.conf.in b/src/journal-remote/journal-upload.conf.in
index 5f59a6fe80..7d2bdc7501 100644
--- a/src/journal-remote/journal-upload.conf.in
+++ b/src/journal-remote/journal-upload.conf.in
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See journal-upload.conf(5) for details
+# See journal-upload.conf(5) for details.
 
 [Upload]
 # URL=
diff --git a/src/journal/journald.conf b/src/journal/journald.conf
index 2e1aacd8c5..ee674ebefe 100644
--- a/src/journal/journald.conf
+++ b/src/journal/journald.conf
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See journald.conf(5) for details.
 
diff --git a/src/login/logind.conf.in b/src/login/logind.conf.in
index 8b220267f3..800c452a60 100644
--- a/src/login/logind.conf.in
+++ b/src/login/logind.conf.in
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See logind.conf(5) for details.
 
diff --git a/src/network/networkd.conf b/src/network/networkd.conf
index 5339e5e5ed..4850ba61f2 100644
--- a/src/network/networkd.conf
+++ b/src/network/networkd.conf
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See networkd.conf(5) for details
+# See networkd.conf(5) for details.
 
 [Network]
 #SpeedMeter=no
diff --git a/src/oom/oomd.conf b/src/oom/oomd.conf
index bd6a9391c6..59e3416bf3 100644
--- a/src/oom/oomd.conf
+++ b/src/oom/oomd.conf
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See oomd.conf(5) for details
 
diff --git a/src/pstore/pstore.conf b/src/pstore/pstore.conf
index 93a8b6707c..7b7b1e8493 100644
--- a/src/pstore/pstore.conf
+++ b/src/pstore/pstore.conf
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See pstore.conf(5) for details.
 
diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in
index e1d06c0fb1..33187618e5 100644
--- a/src/resolve/resolved.conf.in
+++ b/src/resolve/resolved.conf.in
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See resolved.conf(5) for details
+# See resolved.conf(5) for details.
 
 [Resolve]
 # Some examples of DNS servers which may be used for DNS= and FallbackDNS=:
diff --git a/src/sleep/sleep.conf b/src/sleep/sleep.conf
index dc2ed37f70..7c04072d42 100644
--- a/src/sleep/sleep.conf
+++ b/src/sleep/sleep.conf
@@ -1,15 +1,16 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
-# See systemd-sleep.conf(5) for details
+# See systemd-sleep.conf(5) for details.
 
 [Sleep]
 #AllowSuspend=yes
diff --git a/src/timesync/timesyncd.conf.in b/src/timesync/timesyncd.conf.in
index f91c034a01..8a9a14cf0c 100644
--- a/src/timesync/timesyncd.conf.in
+++ b/src/timesync/timesyncd.conf.in
@@ -1,13 +1,14 @@
 #  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.
+#  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.
 #
-# Entries in this file show the compile time defaults.
-# You can change settings by editing this file.
-# Defaults can be restored by simply deleting this file.
+# Entries in this file show the compile time defaults. Local configuration
+# should be created by either modifying this file, or by creating "drop-ins" in
+# the system.conf.d/ subdirectory. The latter is generally recommended.
+# Defaults can be restored by simply deleting this file and all drop-ins.
 #
 # See timesyncd.conf(5) for details.