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1<?xml version='1.0' encoding='UTF-8'?>
2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
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3 6
4<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-rcscripts.xml,v 1.1 2003/11/20 10:52:35 swift Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-rcscripts.xml,v 1.35 2011/08/17 07:57:23 swift Exp $ -->
5 8
6<sections> 9<sections>
10
11<abstract>
12Gentoo uses a special initscript format which, amongst other features, allows
13dependency-driven decisions and virtual initscripts. This chapter explains all
14these aspects and explains how to deal with these scripts.
15</abstract>
16
17<version>4</version>
18<date>2011-08-17</date>
19
7<section> 20<section>
8<title>Runlevels</title> 21<title>Runlevels</title>
9<subsection> 22<subsection>
23<title>Booting your System</title>
24<body>
25
26<p>
27When you boot your system, you will notice lots of text floating by. If you pay
28close attention, you will notice this text is the same every time you reboot
29your system. The sequence of all these actions is called the <e>boot
30sequence</e> and is (more or less) statically defined.
31</p>
32
33<p>
34First, your boot loader will load the kernel image you have defined in the
35boot loader configuration into memory after which it tells the CPU to run the
36kernel. When the kernel is loaded and run, it initializes all kernel-specific
37structures and tasks and starts the <c>init</c> process.
38</p>
39
40<p>
41This process then makes sure that all filesystems (defined in
42<path>/etc/fstab</path>) are mounted and ready to be used. Then it executes
43several scripts located in <path>/etc/init.d</path>, which will start the
44services you need in order to have a successfully booted system.
45</p>
46
47<p>
48Finally, when all scripts are executed, <c>init</c> activates the terminals
49(in most cases just the virtual consoles which are hidden beneath <c>Alt-F1</c>,
50<c>Alt-F2</c>, etc.) attaching a special process called <c>agetty</c> to it.
51This process will then make sure you are able to log on through these terminals
52by running <c>login</c>.
53</p>
54
55</body>
56</subsection>
57<subsection>
58<title>Init Scripts</title>
59<body>
60
61<p>
62Now <c>init</c> doesn't just execute the scripts in <path>/etc/init.d</path>
63randomly. Even more, it doesn't run all scripts in <path>/etc/init.d</path>,
64only the scripts it is told to execute. It decides which scripts to execute by
65looking into <path>/etc/runlevels</path>.
66</p>
67
68<p>
69First, <c>init</c> runs all scripts from <path>/etc/init.d</path> that have
70symbolic links inside <path>/etc/runlevels/boot</path>. Usually, it will
71start the scripts in alphabetical order, but some scripts have dependency
72information in them, telling the system that another script must be run before
73they can be started.
74</p>
75
76<p>
77When all <path>/etc/runlevels/boot</path> referenced scripts are executed,
78<c>init</c> continues with running the scripts that have a symbolic link to them
79in <path>/etc/runlevels/default</path>. Again, it will use the alphabetical
80order to decide what script to run first, unless a script has dependency
81information in it, in which case the order is changed to provide a valid
82start-up sequence.
83</p>
84
85</body>
86</subsection>
87<subsection>
88<title>How Init Works</title>
89<body>
90
91<p>
92Of course <c>init</c> doesn't decide all that by itself. It needs a
93configuration file that specifies what actions need to be taken. This
94configuration file is <path>/etc/inittab</path>.
95</p>
96
97<p>
98If you remember the boot sequence we have just described, you will remember
99that <c>init</c>'s first action is to mount all filesystems. This is defined in
100the following line from <path>/etc/inittab</path>:
101</p>
102
103<pre caption="The system initialisation line in /etc/inittab">
104si::sysinit:/sbin/rc sysinit
105</pre>
106
107<p>
108This line tells <c>init</c> that it must run <c>/sbin/rc sysinit</c> to
109initialize the system. The <path>/sbin/rc</path> script takes care of the
110initialisation, so you might say that <c>init</c> doesn't do much -- it
111delegates the task of initialising the system to another process.
112</p>
113
114<p>
115Second, <c>init</c> executed all scripts that had symbolic links in
116<path>/etc/runlevels/boot</path>. This is defined in the following line:
117</p>
118
119<pre caption="The system initialisation, continued">
120rc::bootwait:/sbin/rc boot
121</pre>
122
123<p>
124Again the <c>rc</c> script performs the necessary tasks. Note that the option
125given to <c>rc</c> (<e>boot</e>) is the same as the subdirectory of
126<path>/etc/runlevels</path> that is used.
127</p>
128
129<p>
130Now <c>init</c> checks its configuration file to see what <e>runlevel</e> it
131should run. To decide this, it reads the following line from
132<path>/etc/inittab</path>:
133</p>
134
135<pre caption="The initdefault line">
136id:3:initdefault:
137</pre>
138
139<p>
140In this case (which the majority of Gentoo users will use), the <e>runlevel</e>
141id is 3. Using this information, <c>init</c> checks what it must run to start
142<e>runlevel 3</e>:
143</p>
144
145<pre caption="The runlevel definitions">
146l0:0:wait:/sbin/rc shutdown
147l1:S1:wait:/sbin/rc single
148l2:2:wait:/sbin/rc nonetwork
149l3:3:wait:/sbin/rc default
150l4:4:wait:/sbin/rc default
151l5:5:wait:/sbin/rc default
152l6:6:wait:/sbin/rc reboot
153</pre>
154
155<p>
156The line that defines level 3, again, uses the <c>rc</c> script to start the
157services (now with argument <e>default</e>). Again note that the argument of
158<c>rc</c> is the same as the subdirectory from <path>/etc/runlevels</path>.
159</p>
160
161<p>
162When <c>rc</c> has finished, <c>init</c> decides what virtual consoles it should
163activate and what commands need to be run at each console:
164</p>
165
166<pre caption="The virtual consoles definition">
167c1:12345:respawn:/sbin/agetty 38400 tty1 linux
168c2:12345:respawn:/sbin/agetty 38400 tty2 linux
169c3:12345:respawn:/sbin/agetty 38400 tty3 linux
170c4:12345:respawn:/sbin/agetty 38400 tty4 linux
171c5:12345:respawn:/sbin/agetty 38400 tty5 linux
172c6:12345:respawn:/sbin/agetty 38400 tty6 linux
173</pre>
174
175
176</body>
177</subsection>
178<subsection>
10<title>What is a runlevel?</title> 179<title>What is a runlevel?</title>
11<body> 180<body>
12 181
182<p>
183You have seen that <c>init</c> uses a numbering scheme to decide what
184<e>runlevel</e> it should activate. A <e>runlevel</e> is a state in which
185your system is running and contains a collection of scripts (runlevel scripts or
186<e>initscripts</e>) that must be executed when you enter or leave a runlevel.
187</p>
188
189<p>
190In Gentoo, there are seven runlevels defined: three internal runlevels, and four
191user-defined runlevels. The internal runlevels are called <e>sysinit</e>,
192<e>shutdown</e> and <e>reboot</e> and do exactly what their names imply:
193initialize the system, powering off the system and rebooting the system.
194</p>
195
196<p>
197The user-defined runlevels are those with an accompanying
198<path>/etc/runlevels</path> subdirectory: <path>boot</path>,
199<path>default</path>, <path>nonetwork</path> and <path>single</path>. The
200<path>boot</path> runlevel starts all system-necessary services which all other
201runlevels use. The remaining three runlevels differ in what services they start:
202<path>default</path> is used for day-to-day operations, <path>nonetwork</path>
203is used in case no network connectivity is required, and <path>single</path> is
204used when you need to fix the system.
205</p>
206
13</body> 207</body>
14</subsection>
15<subsection> 208</subsection>
16<title>We are different :)</title>
17<body>
18
19</body>
20</subsection> 209<subsection>
21<subsection>
22<title>Runlevels</title>
23<body>
24
25</body>
26</subsection>
27<subsection>
28<title>Working with the initscripts</title> 210<title>Working with the Init Scripts</title>
29<body> 211<body>
212
213<p>
214The scripts that the <c>rc</c> process starts are called <e>init scripts</e>.
215Each script in <path>/etc/init.d</path> can be executed with the arguments
216<e>start</e>, <e>stop</e>, <e>restart</e>, <e>pause</e>, <e>zap</e>,
217<e>status</e>, <e>ineed</e>, <e>iuse</e>, <e>needsme</e>, <e>usesme</e> or
218<e>broken</e>.
219</p>
220
221<p>
222To start, stop or restart a service (and all depending services), <c>start</c>,
223<c>stop</c> and <c>restart</c> should be used:
224</p>
225
226<pre caption="Starting Postfix">
227# <i>/etc/init.d/postfix start</i>
228</pre>
229
230<note>
231Only the services that <e>need</e> the given service are stopped or restarted.
232The other depending services (those that <e>use</e> the service but don't need
233it) are left untouched.
234</note>
235
236<p>
237If you want to stop a service, but not the services that depend on it, you can
238use the <c>pause</c> argument:
239</p>
240
241<pre caption="Stopping Postfix but keep the depending services running">
242# <i>/etc/init.d/postfix pause</i>
243</pre>
244
245<p>
246If you want to see what status a service has (started, stopped, paused, ...) you
247can use the <c>status</c> argument:
248</p>
249
250<pre caption="Status information for postfix">
251# <i>/etc/init.d/postfix status</i>
252</pre>
253
254<p>
255If the status information tells you that the service is running, but you know
256that it is not, then you can reset the status information to "stopped" with the
257<c>zap</c> argument:
258</p>
259
260<pre caption="Resetting status information for postfix">
261# <i>/etc/init.d/postfix zap</i>
262</pre>
263
264<p>
265To also ask what dependencies the service has, you can use <c>iuse</c> or
266<c>ineed</c>. With <c>ineed</c> you can see the services that are really
267necessary for the correct functioning of the service. <c>iuse</c> on the other
268hand shows the services that can be used by the service, but are not necessary
269for the correct functioning.
270</p>
271
272<pre caption="Requesting a list of all necessary services on which Postfix depends">
273# <i>/etc/init.d/postfix ineed</i>
274</pre>
275
276<p>
277Similarly, you can ask what services require the service (<c>needsme</c>) or can
278use it (<c>usesme</c>):
279</p>
280
281<pre caption="Requesting a list of all services that require Postfix">
282# <i>/etc/init.d/postfix needsme</i>
283</pre>
284
285<p>
286Finally, you can ask what dependencies the service requires that are missing:
287</p>
288
289<pre caption="Requesting a list of missing dependencies for Postfix">
290# <i>/etc/init.d/postfix broken</i>
291</pre>
30 292
31</body> 293</body>
32</subsection> 294</subsection>
33</section> 295</section>
34<section> 296<section>
35<title>Working with rc-update</title> 297<title>Working with rc-update</title>
36<subsection> 298<subsection>
37<title>What is rc-update?</title> 299<title>What is rc-update?</title>
38<body> 300<body>
39 301
302<p>
303Gentoo's init system uses a dependency-tree to decide what service needs to be
304started first. As this is a tedious task that we wouldn't want our users to
305have to do manually, we have created tools that ease the administration of the
306runlevels and init scripts.
307</p>
308
309<p>
310With <c>rc-update</c> you can add and remove init scripts to a runlevel. The
311<c>rc-update</c> tool will then automatically ask the <c>depscan.sh</c> script
312to rebuild the dependency tree.
313</p>
314
40</body> 315</body>
41</subsection> 316</subsection>
42<subsection> 317<subsection>
43<title>Adding and Removing Services</title> 318<title>Adding and Removing Services</title>
44<body> 319<body>
45 320
46</body> 321<p>
47</subsection> 322You have already added init scripts to the "default" runlevel during the
48<subsection> 323installation of Gentoo. At that time you might not have had a clue what the
49<title>Other rc-update Magic</title> 324"default" is for, but now you should. The <c>rc-update</c> script requires a
50<body> 325second argument that defines the action: <e>add</e>, <e>del</e> or <e>show</e>.
326</p>
327
328<p>
329To add or remove an init script, just give <c>rc-update</c> the <c>add</c> or
330<c>del</c> argument, followed by the init script and the runlevel. For instance:
331</p>
332
333<pre caption="Removing Postfix from the default runlevel">
334# <i>rc-update del postfix default</i>
335</pre>
336
337<p>
338The <c>rc-update -v show</c> command will show all the available init scripts and
339list at which runlevels they will execute:
340</p>
341
342<pre caption="Receiving init script information">
343# <i>rc-update -v show</i>
344</pre>
345
346<p>
347You can also run <c>rc-update show</c> (without <c>-v</c>) to just view enabled
348init scripts and their runlevels.
349</p>
51 350
52</body> 351</body>
53</subsection> 352</subsection>
54</section> 353</section>
55<section> 354<section>
56<title>Configuring Services</title> 355<title>Configuring Services</title>
57<subsection> 356<subsection>
58<title>Why the need for extra configuration?</title> 357<title>Why the Need for Extra Configuration?</title>
59<body> 358<body>
359
360<p>
361Init scripts can be quite complex. It is therefore not really desirable to
362have the users edit the init script directly, as it would make it more
363error-prone. It is however important to be able to configure such a service. For
364instance, you might want to give more options to the service itself.
365</p>
366
367<p>
368A second reason to have this configuration outside the init script is to be
369able to update the init scripts without the fear that your configuration
370changes will be undone.
371</p>
60 372
61</body> 373</body>
62</subsection> 374</subsection>
63<subsection> 375<subsection>
64<title>The /etc/conf.d Directory</title> 376<title>The /etc/conf.d Directory</title>
65<body> 377<body>
378
379<p>
380Gentoo provides an easy way to configure such a service: every init script that
381can be configured has a file in <path>/etc/conf.d</path>. For instance, the
382apache2 initscript (called <path>/etc/init.d/apache2</path>) has a
383configuration file called <path>/etc/conf.d/apache2</path>, which can contain
384the options you want to give to the Apache 2 server when it is started:
385</p>
386
387<pre caption="Variable defined in /etc/conf.d/apache2">
388APACHE2_OPTS="-D PHP5"
389</pre>
390
391<p>
392Such a configuration file contains variables and variables alone (just like
393<path>/etc/make.conf</path>), making it very easy to configure services. It also
394allows us to provide more information about the variables (as comments).
395</p>
66 396
67</body> 397</body>
68</subsection> 398</subsection>
69</section> 399</section>
70<section> 400<section>
71<title>Writing Initscripts</title> 401<title>Writing Init Scripts</title>
72<subsection> 402<subsection>
73<title>Do I Have To?</title> 403<title>Do I Have To?</title>
74<body> 404<body>
75 405
406<p>
407No, writing an init script is usually not necessary as Gentoo provides
408ready-to-use init scripts for all provided services. However, you might have
409installed a service without using Portage, in which case you will most likely
410have to create an init script.
411</p>
412
413<p>
414Do not use the init script provided by the service if it isn't explicitly
415written for Gentoo: Gentoo's init scripts are not compatible with the init
416scripts used by other distributions!
417</p>
418
76</body> 419</body>
77</subsection> 420</subsection>
78<subsection> 421<subsection>
79<title>Layout</title> 422<title>Layout</title>
80<body> 423<body>
81 424
425<p>
426The basic layout of an init script is shown below.
427</p>
428
429<pre caption="Basic layout of an init script">
430#!/sbin/runscript
431
432depend() {
433 <comment>(Dependency information)</comment>
434}
435
436start() {
437 <comment>(Commands necessary to start the service)</comment>
438}
439
440stop() {
441 <comment>(Commands necessary to stop the service)</comment>
442}
443</pre>
444
445<p>
446Any init script <e>requires</e> the <c>start()</c> function to be defined. All
447other sections are optional.
448</p>
449
82</body> 450</body>
83</subsection> 451</subsection>
84<subsection> 452<subsection>
85<title>Dependencies</title> 453<title>Dependencies</title>
86<body> 454<body>
87 455
456<p>
457There are two dependency-alike settings you can define that influence the
458start-up or sequencing of init scripts: <c>use</c> and <c>need</c>. Next to
459these two, there are also two order-influencing methods called <c>before</c> and
460<c>after</c>. These last two are no dependencies per se - they do not make the
461original init script fail if the selected one isn't scheduled to start (or fails
462to start).
463</p>
464
465<ul>
466 <li>
467 The <c>use</c> settings informs the init system that this script <e>uses</e>
468 functionality offered by the selected script, but does not directly depend
469 on it. A good example would be <c>use logger</c> or <c>use dns</c>. If those
470 services are available, they will be put in good use, but if you do not have
471 a logger or DNS server the services will still work. If the services exist,
472 then they are started before the script that <c>use</c>'s them.
473 </li>
474 <li>
475 The <c>need</c> setting is a hard dependency. It means that the script that
476 is <c>need</c>'ing another script will not start before the other script is
477 launched successfully. Also, if that other script is restarted, then this
478 one will be restarted as well.
479 </li>
480 <li>
481 When using <c>before</c>, then the given script is launched before the
482 selected one <e>if</e> the selected one is part of the init level. So an
483 init script <path>xdm</path> that defines <c>before alsasound</c> will start
484 before the <path>alsasound</path> script, but only if <path>alsasound</path>
485 is scheduled to start as well in the same init level. If
486 <path>alsasound</path> is not scheduled to start too, then this particular
487 setting has no effect and <path>xdm</path> will be started when the init
488 system deems it most appropriate.
489 </li>
490 <li>
491 Similarly, <c>after</c> informs the init system that the given script should
492 be launched after the selected one <e>if</e> the selected one is part of the
493 init level. If not, then the setting has no effect and the script will be
494 launched by the init system when it deems it most appropriate.
495 </li>
496</ul>
497
498<p>
499It should be clear from the above that <c>need</c> is the only "true" dependency
500setting as it affects if the script will be started or not. All the others are
501merely pointers towards the init system to clarify in which order scripts can be
502(or should be) launched.
503</p>
504
505<p>
506Now, if you look at many of Gentoo's available init scripts, you will notice
507that some have dependencies on things that are no init scripts. These "things"
508we call <e>virtuals</e>.
509</p>
510
511<p>
512A <e>virtual</e> dependency is a dependency that a service provides, but that is
513not provided solely by that service. Your init script can depend on a system
514logger, but there are many system loggers available (metalogd, syslog-ng,
515sysklogd, ...). As you cannot <c>need</c> every single one of them (no sensible
516system has all these system loggers installed and running) we made sure that
517all these services <c>provide</c> a virtual dependency.
518</p>
519
520<p>
521Let us take a look at the dependency information for the postfix service.
522</p>
523
524<pre caption="Dependency information for Postfix">
525depend() {
526 need net
527 use logger dns
528 provide mta
529}
530</pre>
531
532<p>
533As you can see, the postfix service:
534</p>
535
536<ul>
537 <li>
538 requires the (virtual) <c>net</c> dependency (which is provided by, for
539 instance, <path>/etc/init.d/net.eth0</path>)
540 </li>
541 <li>
542 uses the (virtual) <c>logger</c> dependency (which is provided by, for
543 instance, <path>/etc/init.d/syslog-ng</path>)
544 </li>
545 <li>
546 uses the (virtual) <c>dns</c> dependency (which is provided by, for
547 instance, <path>/etc/init.d/named</path>)
548 </li>
549 <li>
550 provides the (virtual) <c>mta</c> dependency (which is common for all mail
551 servers)
552 </li>
553</ul>
554
88</body> 555</body>
89</subsection> 556</subsection>
90<subsection> 557<subsection>
91<title>Controlling the Order</title> 558<title>Controlling the Order</title>
92<body> 559<body>
93 560
94</body> 561<p>
95</subsection> 562As we described in the previous section, you can tell the init system what order
96<subsection> 563it should use for starting (or stopping) scripts. This ordering is handled both
97<title>Virtual Services</title> 564through the dependency settings <c>use</c> and <c>need</c>, but also through the
98<body> 565order settings <c>before</c> and <c>after</c>. As we have described these
566earlier already, let's take a look at the Portmap service as an example of such
567init script.
568</p>
569
570<pre caption="The depend() function in the Portmap service">
571depend() {
572 need net
573 before inetd
574 before xinetd
575}
576</pre>
577
578<p>
579You can also use the "*" glob to catch all services in the same runlevel,
580although this isn't advisable.
581</p>
582
583<pre caption="Running an init script as first script in the runlevel">
584depend() {
585 before *
586}
587</pre>
588
589<p>
590If your service must write to local disks, it should need <c>localmount</c>. If
591it places anything in <path>/var/run</path> such as a pidfile, then it should
592start after <c>bootmisc</c>:
593</p>
594
595<pre caption="Example depend() function">
596depend() {
597 need localmount
598 after bootmisc
599}
600</pre>
99 601
100</body> 602</body>
101</subsection> 603</subsection>
102<subsection> 604<subsection>
103<title>Standard Functions</title> 605<title>Standard Functions</title>
104<body> 606<body>
105 607
608<p>
609Next to the <c>depend()</c> functionality, you also need to define the
610<c>start()</c> function. This one contains all the commands necessary to
611initialize your service. It is advisable to use the <c>ebegin</c> and
612<c>eend</c> functions to inform the user about what is happening:
613</p>
614
615<pre caption="Example start() function">
616start() {
617 if [ "${RC_CMD}" = "restart" ];
618 then
619 <comment># Do something in case a restart requires more than stop, start</comment>
620 fi
621
622 ebegin "Starting my_service"
623 start-stop-daemon --start --exec /path/to/my_service \
624 --pidfile /path/to/my_pidfile
625 eend $?
626}
627</pre>
628
629<p>
630Both <c>--exec</c> and <c>--pidfile</c> should be used in start and stop
631functions. If the service does not create a pidfile, then use
632<c>--make-pidfile</c> if possible, though you should test this to be sure.
633Otherwise, don't use pidfiles. You can also add <c>--quiet</c> to the
634<c>start-stop-daemon</c> options, but this is not recommended unless the
635service is extremely verbose. Using <c>--quiet</c> may hinder debugging if the
636service fails to start.
637</p>
638
639<p>
640Another notable setting used in the above example is to check the contents of
641the <c>RC_CMD</c> variable. Unlike the previous init script system, the newer
642<c>openrc</c> system does not support script-specific restart functionality.
643Instead, the script needs to check the contents of the <c>RC_CMD</c> variable
644to see if a function (be it <c>start()</c> or <c>stop()</c>) is called as part
645of a restart or not.
646</p>
647
648<note>
649Make sure that <c>--exec</c> actually calls a service and not just a shell
650script that launches services and exits -- that's what the init script is
651supposed to do.
652</note>
653
654<p>
655If you need more examples of the <c>start()</c> function, please read the
656source code of the available init scripts in your <path>/etc/init.d</path>
657directory.
658</p>
659
660<p>
661Another function you can define is <c>stop()</c>. You are not obliged to define
662this function though! Our init system is intelligent enough to fill in this
663function by itself if you use <c>start-stop-daemon</c>.
664</p>
665
666<p>
667Here is an example of a <c>stop()</c> function:
668</p>
669
670<pre caption="Example stop() function">
671stop() {
672 ebegin "Stopping my_service"
673 start-stop-daemon --stop --exec /path/to/my_service \
674 --pidfile /path/to/my_pidfile
675 eend $?
676}
677</pre>
678
679<p>
680If your service runs some other script (for example, bash, python, or perl),
681and this script later changes names (for example, <c>foo.py</c> to <c>foo</c>),
682then you will need to add <c>--name</c> to <c>start-stop-daemon</c>. You must
683specify the name that your script will be changed to. In this example, a
684service starts <c>foo.py</c>, which changes names to <c>foo</c>:
685</p>
686
687<pre caption="A service that starts the foo script">
688start() {
689 ebegin "Starting my_script"
690 start-stop-daemon --start --exec /path/to/my_script \
691 --pidfile /path/to/my_pidfile --name foo
692 eend $?
693}
694</pre>
695
696<p>
697<c>start-stop-daemon</c> has an excellent man page available if you need more
698information:
699</p>
700
701<pre caption="Getting the man page for start-stop-daemon">
702$ <i>man start-stop-daemon</i>
703</pre>
704
705<p>
706Gentoo's init script syntax is based on the Bourne Again Shell (bash) so you are
707free to use bash-compatible constructs inside your init script. However, you may
708want to write your init scripts to be POSIX-compliant. Future init script
709systems may allow symlinking <path>/bin/sh</path> to other shells besides
710bash. Init scripts that rely on bash-only features will then break these
711configurations.
712</p>
713
106</body> 714</body>
107</subsection> 715</subsection>
108<subsection> 716<subsection>
109<title>Adding Custom Options</title> 717<title>Adding Custom Options</title>
110<body> 718<body>
111 719
720<p>
721If you want your init script to support more options than the ones we have
722already encountered, you should add the option to the <c>opts</c> variable, and
723create a function with the same name as the option. For instance, to support an
724option called <c>restartdelay</c>:
725</p>
726
727<pre caption="Supporting the restartdelay option">
728opts="${opts} restartdelay"
729
730restartdelay() {
731 stop
732 sleep 3 <comment># Wait 3 seconds before starting again</comment>
733 start
734}
735</pre>
736
737<impo>
738The function <c>restart()</c> cannot be overridden in openrc!
739</impo>
740
112</body> 741</body>
113</subsection> 742</subsection>
114<subsection> 743<subsection>
115<title>Service Configuration Variables</title> 744<title>Service Configuration Variables</title>
116<body> 745<body>
746
747<p>
748You don't have to do anything to support a configuration file in
749<path>/etc/conf.d</path>: if your init script is executed, the following files
750are automatically sourced (i.e. the variables are available to use):
751</p>
752
753<ul>
754 <li><path>/etc/conf.d/&lt;your init script&gt;</path></li>
755 <li><path>/etc/conf.d/basic</path></li>
756 <li><path>/etc/rc.conf</path></li>
757</ul>
758
759<p>
760Also, if your init script provides a virtual dependency (such as <c>net</c>),
761the file associated with that dependency (such as <path>/etc/conf.d/net</path>)
762will be sourced too.
763</p>
764
765</body>
766</subsection>
767</section>
768<section>
769<title>Changing the Runlevel Behaviour</title>
770<subsection>
771<title>Who might benefit from this?</title>
772<body>
773
774<p>
775Many laptop users know the situation: at home you need to start <c>net.eth0</c>
776while you don't want to start <c>net.eth0</c> while you're on the road (as
777there is no network available). With Gentoo you can alter the runlevel behaviour
778to your own will.
779</p>
780
781<p>
782For instance you can create a second "default" runlevel which you can boot that
783has other init scripts assigned to it. You can then select at boottime what
784default runlevel you want to use.
785</p>
786
787</body>
788</subsection>
789<subsection>
790<title>Using softlevel</title>
791<body>
792
793<p>
794First of all, create the runlevel directory for your second "default" runlevel.
795As an example we create the <path>offline</path> runlevel:
796</p>
797
798<pre caption="Creating a runlevel directory">
799# <i>mkdir /etc/runlevels/offline</i>
800</pre>
801
802<p>
803Add the necessary init scripts to the newly created runlevels. For instance, if
804you want to have an exact copy of your current <c>default</c> runlevel but
805without <c>net.eth0</c>:
806</p>
807
808<pre caption="Adding the necessary init scripts">
809<comment>(Copy all services from default runlevel to offline runlevel)</comment>
810# <i>cd /etc/runlevels/default</i>
811# <i>for service in *; do rc-update add $service offline; done</i>
812<comment>(Remove unwanted service from offline runlevel)</comment>
813# <i>rc-update del net.eth0 offline</i>
814<comment>(Display active services for offline runlevel)</comment>
815# <i>rc-update show offline</i>
816<comment>(Partial sample Output)</comment>
817 acpid | offline
818 domainname | offline
819 local | offline
820 net.eth0 |
821</pre>
822
823<p>
824Even though <c>net.eth0</c> has been removed from the offline runlevel,
825<c>udev</c> might want to attempt to start any devices it detects and launch the
826appropriate services, a functionality that is called <e>hotplugging</e>. By
827default, Gentoo does not enable hotplugging.
828</p>
829
830<p>
831If you do want to enable hotplugging, but only for a selected set of scripts,
832use the <c>rc_hotplug</c> variable in <path>/etc/rc.conf</path>:
833</p>
834
835<pre caption="Disabling device initiated services in /etc/rc.conf">
836<comment># Allow net.wlan as well as any other service, except those matching net.*
837# to be hotplugged</comment>
838rc_hotplug="net.wlan !net.*"
839</pre>
840
841<note>
842For more information on device initiated services, please see the comments
843inside <path>/etc/rc.conf</path>.
844</note>
845
846<p>
847Now edit your bootloader configuration and add a new entry for the
848<c>offline</c> runlevel. For instance, in <path>/boot/grub/grub.conf</path>:
849</p>
850
851<pre caption="Adding an entry for the offline runlevel">
852title Gentoo Linux Offline Usage
853 root (hd0,0)
854 kernel (hd0,0)/kernel-2.4.25 root=/dev/hda3 <i>softlevel=offline</i>
855</pre>
856
857<p>
858VoilĂ , you're all set now. If you boot your system and select the newly added
859entry at boot, the <c>offline</c> runlevel will be used instead of the
860<c>default</c> one.
861</p>
862
863</body>
864</subsection>
865<subsection>
866<title>Using bootlevel</title>
867<body>
868
869<p>
870Using <c>bootlevel</c> is completely analogous to <c>softlevel</c>. The only
871difference here is that you define a second "boot" runlevel instead of a second
872"default" runlevel.
873</p>
117 874
118</body> 875</body>
119</subsection> 876</subsection>
120</section> 877</section>
121</sections> 878</sections>

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