[Pkg-sysvinit-devel] [PATCH 2/2] update-rc.d: add from ... to ... interface
Kel Modderman
kel at otaku42.de
Mon Aug 25 12:53:28 UTC 2008
When run with the from ... to ... options, update-rc.d can migrate the runlevel
links for a script from old defaults to new defaults while preserving any
local modifications.
It is intended that this be used only in maintainer scripts of packages wishing
to change the runlevel link configuration for a service script while preserving
locally modified link configurations.
Real world example
==================
Package `hotkey-setup' used default dh_installinit settings up until package
version 0.1-17.2. In all of those package versions, the dh_installinit
autogenerated section of hotkey-setup.postinst contained the update-rc.d
command: "update-rc.d hotkey-setup defaults"
In hotkey-setup package version 0.1-17.2, the postinst maintainer script looks
like:
===
# Remove symlinks to script to have them reinserted by debhelper
# without the shutdown and reboot links; this init script does not
# need them.
if dpkg --compare-versions "$2" lt "0.1-17.2"; then
update-rc.d -f hotkey-setup remove
fi
#DEBHELPER#
===
Installation of this version of hotkey-setup would force the purge of existing
runlevel links for /etc/init.d/hotkey-setup, so that the new dh_installinit
autogenerated update-rc.d command could take effect. This practise does not
preserve administrator modified runlevel configuration and is therefore prone
to error, policy violation bugs and end user complaint.
Using the "from ... to ..." feature, the same result could have been achieved
with a postinst snippet similar to:
===
# Drop shutdown link from runlevels 0 and 6, this package does not require them
if dpkg --compare-versions "$2" lt "0.1-17.2"; then
update-rc.d hotkey-setup from defaults to start 20 2 3 4 5 . stop 20 1 .
fi
#DEBHELPER#
===
See also: http://lists.debian.org/debian-devel/2008/01/msg00007.html
Examples
========
# Establish initial runlevel configuration
$ update-rc.d hotkey-setup defaults
Adding system startup for /etc/init.d/hotkey-setup ...
/etc/rc0.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc1.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc6.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc2.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc3.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc4.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc5.d/S20hotkey-setup -> ../init.d/hotkey-setup
/
`-- etc
|-- init.d
| `-- hotkey-setup
|-- rc0.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc1.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc2.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc3.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc4.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc5.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc6.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
`-- rcS.d
# Modify default runlevel link to scheme without link in runlevel 0 and 6
$ update-rc.d hotkey-setup from defaults to start 20 2 3 4 5 . stop 20 1 .
Preparing to modify system startup links for /etc/init.d/hotkey-setup ...
Modifying system startup links for /etc/init.d/hotkey-setup ...
Removing any system startup links for /etc/init.d/hotkey-setup ...
/etc/rc0.d/K20hotkey-setup
/etc/rc1.d/K20hotkey-setup
/etc/rc2.d/S20hotkey-setup
/etc/rc3.d/S20hotkey-setup
/etc/rc4.d/S20hotkey-setup
/etc/rc5.d/S20hotkey-setup
/etc/rc6.d/K20hotkey-setup
Adding system startup for /etc/init.d/hotkey-setup ...
/etc/rc1.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc2.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc3.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc4.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc5.d/S20hotkey-setup -> ../init.d/hotkey-setup
/
`-- etc
|-- init.d
| `-- hotkey-setup
|-- rc0.d
|-- rc1.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc2.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc3.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc4.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc5.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc6.d
`-- rcS.d
# The admin decides for whatever reason to remove these links
$ update-rc.d -f hotkey-setup remove
Removing any system startup links for /etc/init.d/hotkey-setup ...
/etc/rc1.d/K20hotkey-setup
/etc/rc2.d/S20hotkey-setup
/etc/rc3.d/S20hotkey-setup
/etc/rc4.d/S20hotkey-setup
/etc/rc5.d/S20hotkey-setup
# Try the same modifcation command as before, but no links exist this time
$ update-rc.d hotkey-setup from defaults to start 20 2 3 4 5 . stop 20 1 .
System startup links for /etc/init.d/hotkey-setup do not exist.
# Restablish default configuration
$ update-rc.d hotkey-setup defaults
Adding system startup for /etc/init.d/hotkey-setup ...
/etc/rc0.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc1.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc6.d/K20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc2.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc3.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc4.d/S20hotkey-setup -> ../init.d/hotkey-setup
/etc/rc5.d/S20hotkey-setup -> ../init.d/hotkey-setup
# Admin manually modifies runlevel configuration
$ mv /etc/rc5.d/S20hotkey-setup /etc/rc5.d/K20hotkey-setup
# Try the same modifcation command as before, showing how modified runlevel
# configuration is preserved
$ update-rc.d hotkey-setup from defaults to start 20 2 3 4 5 . stop 20 1 .
Preparing to modify system startup links for /etc/init.d/hotkey-setup ...
update-rc.d: warning: /etc/rc5.d/S20hotkey-setup is not a symbolic link
Preserving locally modified system startup links for /etc/init.d/hotkey-setup ...
/
`-- etc
|-- init.d
| `-- hotkey-setup
|-- rc0.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc1.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc2.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc3.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc4.d
| `-- S20hotkey-setup -> ../init.d/hotkey-setup
|-- rc5.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
|-- rc6.d
| `-- K20hotkey-setup -> ../init.d/hotkey-setup
`-- rcS.d
---
--- a/debian/sysv-rc/sbin/update-rc.d
+++ b/debian/sysv-rc/sbin/update-rc.d
@@ -18,6 +18,7 @@
usage: update-rc.d [-n] [-f] <basename> remove
update-rc.d [-n] <basename> defaults [NN | SS KK]
update-rc.d [-n] <basename> start|stop NN runlvl [runlvl] [...] .
+ update-rc.d [-n] <basename> from [...] to [...]
-n: not really
-f: force
EOF
@@ -63,6 +64,7 @@
$_ = $ARGV[0];
if (/^remove$/) { &checklinks ("remove"); }
+elsif (/^from$/) { &fromto (@ARGV); &makelinks; }
elsif (/^defaults$/) { &defaults (@ARGV); &makelinks; }
elsif (/^(start|stop)$/) { &startstop (@ARGV); &makelinks; }
else { &usage; }
@@ -156,6 +158,61 @@
}
+# Process the arguments after the "from" keyword.
+
+sub fromto {
+ my @argv = @_;
+ my ($defaults, $abort) = (0, 0);
+ my ($i, $islink, @from, @to);
+
+ if (!&checklinks) {
+ print " System startup links for $initd/$bn do not exist.\n";
+ exit (0);
+ }
+
+ while ($#argv >= 0 && shift @argv) {
+ if ($argv[0] eq 'to') { @to = @argv; last; }
+ elsif ($argv[0] eq 'defaults') { $defaults++ }
+ push(@from, $argv[0]);
+ }
+
+ &usage ("expected 'to' keyword") if ($to[0] ne 'to');
+ shift @to;
+
+ print " Preparing to modify system startup links for $initd/$bn ...\n";
+
+ if ($from[0] eq 'defaults') { &defaults (@from); }
+ else { &startstop (@from); }
+
+ foreach $i (0..$#startlinks) {
+ next if !$startlinks[$i];
+ $islink = &is_link (undef, "$etcd$i.d/$startlinks[$i]$bn", $bn);
+ if (!$islink) { $abort++; }
+ }
+
+ foreach $i (0..$#stoplinks) {
+ next if !$stoplinks[$i];
+ $islink = &is_link (undef, "$etcd$i.d/$stoplinks[$i]$bn", $bn);
+ if (!$islink) { $abort++; }
+ }
+
+ @startlinks = @stoplinks = ();
+
+ if ($abort) {
+ print " Preserving locally modified system startup links for $initd/$bn ...\n";
+ exit (0);
+ }
+
+ if ($to[0] eq 'defaults') { &defaults (@to); }
+ else { &startstop (@to); }
+
+ print " Modifying system startup links for $initd/$bn ...\n";
+
+ &checklinks ("remove");
+
+ 1;
+}
+
# Process the arguments after the "defaults" keyword.
sub defaults {
--- a/debian/sysv-rc/man8/update-rc.d.8
+++ b/debian/sysv-rc/man8/update-rc.d.8
@@ -23,6 +23,13 @@
.BR start | stop
.IR "NN runlevel" " [" runlevel "]..."
.BR . " ..."
+.HP
+.B update-rc.d
+.RI [ -d " path " ]
+.RI [ -n ]
+.I name
+.BR from " defaults|start|stop ... "
+.BR to " defaults|start|stop ... "
.SH DESCRIPTION
.B update-rc.d
updates the System V style init script links
@@ -175,7 +182,7 @@
must exist before
.B update-rc.d
is run to create the links.
-.SH REMOVING SCRIPTS
+.SH REMOVING INIT SCRIPT LINKS
When invoked with the
.I remove
option, update-rc.d removes any links in the
@@ -197,6 +204,32 @@
directories that are not symbolic links to the script
.BI /etc/init.d/ name
will be left untouched.
+.SH MODIFYING INIT SCRIPT LINKS
+When run with the
+.BR from " ... " to " ... "
+options,
+.B update-rc.d
+modifies existing runlevel links for the script
+.BR /etc/init.d/ \fIname\fR.
+.P
+If the current runlevel link configuration for
+.BR /etc/init.d/ \fIname\fR
+could be recreated as if
+.B update-rc.d
+had been called with only the arguments between the
+.B from
+and
+.B to
+keywords, the current links will be removed and replaced with new
+links as if
+.B update-rc.d
+had been called with only the arguments after the
+.B to
+keyword.
+.P
+It is intended that this be used only in maintainer scripts of
+packages wishing to change the runlevel link configuration for a
+service script while preserving locally modified link configurations.
.SH OPTIONS
.TP
@@ -254,6 +287,11 @@
.B " update-rc.d -f foobar remove"
.B " update-rc.d foobar stop 45 S ."
.fi
+Example of a command for modifying existing links for a script that was
+initially installed using the \fIdefaults\fR argument:
+.nf
+.B " update-rc.d foobar from defaults to start 20 2 3 4 5 . stop 20 1 ."
+.fi
.SH BUGS
See http://bugs.debian.org/sysv-rc.
---
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