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2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
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4<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-rcscripts.xml,v 1.5 2003/12/10 14:23:36 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>
10<title>Booting your System</title> 23<title>Booting your System</title>
11<body> 24<body>
18</p> 31</p>
19 32
20<p> 33<p>
21First, your boot loader will load the kernel image you have defined in the 34First, your boot loader will load the kernel image you have defined in the
22boot loader configuration into memory after which it tells the CPU to run the 35boot loader configuration into memory after which it tells the CPU to run the
23kernel. When the kernel is loaded and run, it initialises all kernel-specific 36kernel. When the kernel is loaded and run, it initializes all kernel-specific
24structures and tasks and starts the <c>init</c> process. 37structures and tasks and starts the <c>init</c> process.
25</p> 38</p>
26 39
27<p> 40<p>
28This process then makes sure that all filesystems (defined in 41This process then makes sure that all filesystems (defined in
29<path>/etc/fstab</path>) are mounted and ready to be used. Then it executes 42<path>/etc/fstab</path>) are mounted and ready to be used. Then it executes
30several scripts located in <path>/etc/init.d</path>, which will start the 43several scripts located in <path>/etc/init.d</path>, which will start the
31services you need in order to have a succesfully booted system. 44services you need in order to have a successfully booted system.
32</p> 45</p>
33 46
34<p> 47<p>
35Finally, when all scripts are executed, <c>init</c> activates the terminals 48Finally, when all scripts are executed, <c>init</c> activates the terminals
36(in most cases just the virtual consoles which are hidden beneith <c>Alt-F1</c>, 49(in most cases just the virtual consoles which are hidden beneath <c>Alt-F1</c>,
37<c>Alt-F2</c>, etc.) attaching a special process called <c>agetty</c> to it. 50<c>Alt-F2</c>, etc.) attaching a special process called <c>agetty</c> to it.
38This process will then make sure you are able to log on through these terminals 51This process will then make sure you are able to log on through these terminals
39by running <c>login</c>. 52by running <c>login</c>.
40</p> 53</p>
41 54
46<body> 59<body>
47 60
48<p> 61<p>
49Now <c>init</c> doesn't just execute the scripts in <path>/etc/init.d</path> 62Now <c>init</c> doesn't just execute the scripts in <path>/etc/init.d</path>
50randomly. Even more, it doesn't run all scripts in <path>/etc/init.d</path>, 63randomly. Even more, it doesn't run all scripts in <path>/etc/init.d</path>,
51only the scripts it is told to execute. It decides what scripts to execute by 64only the scripts it is told to execute. It decides which scripts to execute by
52looking into <path>/etc/runlevels</path>. 65looking into <path>/etc/runlevels</path>.
53</p> 66</p>
54 67
55<p> 68<p>
56First, <c>init</c> runs all scripts from <path>/etc/init.d</path> that have 69First, <c>init</c> runs all scripts from <path>/etc/init.d</path> that have
63<p> 76<p>
64When all <path>/etc/runlevels/boot</path> referenced scripts are executed, 77When all <path>/etc/runlevels/boot</path> referenced scripts are executed,
65<c>init</c> continues with running the scripts that have a symbolic link to them 78<c>init</c> continues with running the scripts that have a symbolic link to them
66in <path>/etc/runlevels/default</path>. Again, it will use the alphabetical 79in <path>/etc/runlevels/default</path>. Again, it will use the alphabetical
67order to decide what script to run first, unless a script has dependency 80order to decide what script to run first, unless a script has dependency
68information in it, in which the order is changed to provide a valid start-up 81information in it, in which case the order is changed to provide a valid
69sequence. 82start-up sequence.
70</p> 83</p>
71 84
72</body> 85</body>
73</subsection> 86</subsection>
74<subsection> 87<subsection>
80configuration file that specifies what actions need to be taken. This 93configuration file that specifies what actions need to be taken. This
81configuration file is <path>/etc/inittab</path>. 94configuration file is <path>/etc/inittab</path>.
82</p> 95</p>
83 96
84<p> 97<p>
85If you remember the boot sequence we have just explained to you, you will 98If you remember the boot sequence we have just described, you will remember
86remember that <c>init</c>'s first action is to mount all filesystems. This is 99that <c>init</c>'s first action is to mount all filesystems. This is defined in
87defined in the following line from <path>/etc/inittab</path>: 100the following line from <path>/etc/inittab</path>:
88</p> 101</p>
89 102
90<pre caption="The system initialisation line in /etc/inittab"> 103<pre caption="The system initialisation line in /etc/inittab">
91si::sysinit:/sbin/rc sysinit 104si::sysinit:/sbin/rc sysinit
92</pre> 105</pre>
93 106
94<p> 107<p>
95This line tells <c>init</c> that it must run <c>/sbin/rc sysinit</c> to 108This line tells <c>init</c> that it must run <c>/sbin/rc sysinit</c> to
96initialise the system. The <path>/sbin/rc</path> script takes care of the 109initialize the system. The <path>/sbin/rc</path> script takes care of the
97initialisation, so you might say that <c>init</c> doesn't do much -- it 110initialisation, so you might say that <c>init</c> doesn't do much -- it
98delegates the task of initialising the system to another process. 111delegates the task of initialising the system to another process.
99</p> 112</p>
100 113
101<p> 114<p>
175 188
176<p> 189<p>
177In Gentoo, there are seven runlevels defined: three internal runlevels, and four 190In Gentoo, there are seven runlevels defined: three internal runlevels, and four
178user-defined runlevels. The internal runlevels are called <e>sysinit</e>, 191user-defined runlevels. The internal runlevels are called <e>sysinit</e>,
179<e>shutdown</e> and <e>reboot</e> and do exactly what their names imply: 192<e>shutdown</e> and <e>reboot</e> and do exactly what their names imply:
180initialise the system, powering off the system and rebooting the system. 193initialize the system, powering off the system and rebooting the system.
181</p> 194</p>
182 195
183<p> 196<p>
184The user-defined runlevels are those with an accompanying 197The user-defined runlevels are those with an accompanying
185<path>/etc/runlevels</path> subdirectory: <path>boot</path>, 198<path>/etc/runlevels</path> subdirectory: <path>boot</path>,
268<pre caption="Requesting a list of all services that require Postfix"> 281<pre caption="Requesting a list of all services that require Postfix">
269# <i>/etc/init.d/postfix needsme</i> 282# <i>/etc/init.d/postfix needsme</i>
270</pre> 283</pre>
271 284
272<p> 285<p>
273Finally, you can ask what dependencies the service requires but that are 286Finally, you can ask what dependencies the service requires that are missing:
274missing:
275</p> 287</p>
276 288
277<pre caption="Requesting a list of missing dependencies for Postfix"> 289<pre caption="Requesting a list of missing dependencies for Postfix">
278# <i>/etc/init.d/postfix broken</i> 290# <i>/etc/init.d/postfix broken</i>
279</pre> 291</pre>
287<title>What is rc-update?</title> 299<title>What is rc-update?</title>
288<body> 300<body>
289 301
290<p> 302<p>
291Gentoo's init system uses a dependency-tree to decide what service needs to be 303Gentoo's init system uses a dependency-tree to decide what service needs to be
292started first. As this is a tedious task that we wouldn't want our users to do 304started first. As this is a tedious task that we wouldn't want our users to
293manually, we have created tools that ease the administration of the runlevels 305have to do manually, we have created tools that ease the administration of the
294and init scripts. 306runlevels and init scripts.
295</p> 307</p>
296 308
297<p> 309<p>
298With <c>rc-update</c> you can add and remove init scripts to a runlevel. The 310With <c>rc-update</c> you can add and remove init scripts to a runlevel. The
299<c>rc-update</c> tool will then automatically ask the <c>depscan.sh</c> script 311<c>rc-update</c> tool will then automatically ask the <c>depscan.sh</c> script
306<title>Adding and Removing Services</title> 318<title>Adding and Removing Services</title>
307<body> 319<body>
308 320
309<p> 321<p>
310You have already added init scripts to the "default" runlevel during the 322You have already added init scripts to the "default" runlevel during the
311installation of Gentoo. At that time you might not had a clue what the 323installation of Gentoo. At that time you might not have had a clue what the
312"default" is for, but now you should. The <c>rc-update</c> script requires a 324"default" is for, but now you should. The <c>rc-update</c> script requires a
313second argument that defines the action: <e>add</e>, <e>del</e> or <e>show</e>. 325second argument that defines the action: <e>add</e>, <e>del</e> or <e>show</e>.
314</p> 326</p>
315 327
316<p> 328<p>
321<pre caption="Removing Postfix from the default runlevel"> 333<pre caption="Removing Postfix from the default runlevel">
322# <i>rc-update del postfix default</i> 334# <i>rc-update del postfix default</i>
323</pre> 335</pre>
324 336
325<p> 337<p>
326The <c>rc-update show</c> command will show all the available init scripts and 338The <c>rc-update -v show</c> command will show all the available init scripts and
327list at which runlevels they will execute: 339list at which runlevels they will execute:
328</p> 340</p>
329 341
330<pre caption="Receiving init script information"> 342<pre caption="Receiving init script information">
331# <i>rc-update show</i> 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.
332</pre> 349</p>
333 350
334</body> 351</body>
335</subsection> 352</subsection>
336</section> 353</section>
337<section> 354<section>
339<subsection> 356<subsection>
340<title>Why the Need for Extra Configuration?</title> 357<title>Why the Need for Extra Configuration?</title>
341<body> 358<body>
342 359
343<p> 360<p>
344Init scripts can be quite complex. It is therefore not really interesting to 361Init scripts can be quite complex. It is therefore not really desirable to
345have the users directly edit the init script, as it would make it more 362have the users edit the init script directly, as it would make it more
346error-prone. It is however important to be able to configure such a service. For 363error-prone. It is however important to be able to configure such a service. For
347instance, you might want to give more options to the service itself. 364instance, you might want to give more options to the service itself.
348</p> 365</p>
349 366
350<p> 367<p>
351A second reason to have this configuration outside the init script is to be able 368A second reason to have this configuration outside the init script is to be
352to update the init scripts without being afraid that your configuration changes 369able to update the init scripts without the fear that your configuration
353are undone. 370changes will be undone.
354</p> 371</p>
355 372
356</body> 373</body>
357</subsection> 374</subsection>
358<subsection> 375<subsection>
366configuration file called <path>/etc/conf.d/apache2</path>, which can contain 383configuration file called <path>/etc/conf.d/apache2</path>, which can contain
367the options you want to give to the Apache 2 server when it is started: 384the options you want to give to the Apache 2 server when it is started:
368</p> 385</p>
369 386
370<pre caption="Variable defined in /etc/conf.d/apache2"> 387<pre caption="Variable defined in /etc/conf.d/apache2">
371APACHE2_OPTS="-D PHP4" 388APACHE2_OPTS="-D PHP5"
372</pre> 389</pre>
373 390
374<p> 391<p>
375Such a configuration file contains variables and variables alone (just like 392Such a configuration file contains variables and variables alone (just like
376<path>/etc/make.conf</path>), making it very easy to configure services. It also 393<path>/etc/make.conf</path>), making it very easy to configure services. It also
385<subsection> 402<subsection>
386<title>Do I Have To?</title> 403<title>Do I Have To?</title>
387<body> 404<body>
388 405
389<p> 406<p>
390No. Writing an init script is usually not necessary as Gentoo provides 407No, writing an init script is usually not necessary as Gentoo provides
391ready-to-use init scripts for all provided services. However, you might have 408ready-to-use init scripts for all provided services. However, you might have
392installed a service without using Portage, in which case you will most likely 409installed a service without using Portage, in which case you will most likely
393have to create an init script. 410have to create an init script.
394</p> 411</p>
395 412
421} 438}
422 439
423stop() { 440stop() {
424 <comment>(Commands necessary to stop the service)</comment> 441 <comment>(Commands necessary to stop the service)</comment>
425} 442}
426
427restart() {
428 <comment>(Commands necessary to restart the service)</comment>
429}
430</pre> 443</pre>
431 444
432<p> 445<p>
433Any init script <e>requires</e> the <c>start()</c> function to be defined. All 446Any init script <e>requires</e> the <c>start()</c> function to be defined. All
434other sections are optional. 447other sections are optional.
439<subsection> 452<subsection>
440<title>Dependencies</title> 453<title>Dependencies</title>
441<body> 454<body>
442 455
443<p> 456<p>
444There are two dependencies you can define: <c>use</c> and <c>need</c>. As we 457There are two dependency-alike settings you can define that influence the
445have mentioned before, the <c>need</c> dependency is more strict than the 458start-up or sequencing of init scripts: <c>use</c> and <c>need</c>. Next to
446<c>use</c> dependency. Following this dependency type you enter the service 459these two, there are also two order-influencing methods called <c>before</c> and
447you depend on, or the <e>virtual</e> dependency. 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>.
448</p> 509</p>
449 510
450<p> 511<p>
451A <e>virtual</e> dependency is a dependency that a service provides, but that is 512A <e>virtual</e> dependency is a dependency that a service provides, but that is
452not provided solely by that service. Your init script can depend on a system 513not provided solely by that service. Your init script can depend on a system
496<subsection> 557<subsection>
497<title>Controlling the Order</title> 558<title>Controlling the Order</title>
498<body> 559<body>
499 560
500<p> 561<p>
501In some cases you might not require a service, but want your service to be 562As we described in the previous section, you can tell the init system what order
502started <c>before</c> (or <c>after</c>) another service <e>if</e> it is 563it should use for starting (or stopping) scripts. This ordering is handled both
503available on the system (note the conditional - this is no dependency anymore) 564through the dependency settings <c>use</c> and <c>need</c>, but also through the
504<e>and</e> ran in the same runlevel (note the conditional - only services in the 565order settings <c>before</c> and <c>after</c>. As we have described these
505same runlevel are involved). You can provide this information using the 566earlier already, let's take a look at the Portmap service as an example of such
506<c>before</c> or <c>after</c> settings. 567init script.
507</p>
508
509<p>
510As an example we view the settings of the Portmap service:
511</p> 568</p>
512 569
513<pre caption="The depend() function in the Portmap service"> 570<pre caption="The depend() function in the Portmap service">
514depend() { 571depend() {
515 need net 572 need net
518} 575}
519</pre> 576</pre>
520 577
521<p> 578<p>
522You can also use the "*" glob to catch all services in the same runlevel, 579You can also use the "*" glob to catch all services in the same runlevel,
523although this isn't adviseable. 580although this isn't advisable.
524</p> 581</p>
525 582
526<pre caption="Running an init script as first script in the runlevel"> 583<pre caption="Running an init script as first script in the runlevel">
527depend() { 584depend() {
528 before * 585 before *
529} 586}
530</pre> 587</pre>
531 588
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>
601
532</body> 602</body>
533</subsection> 603</subsection>
534<subsection> 604<subsection>
535<title>Standard Functions</title> 605<title>Standard Functions</title>
536<body> 606<body>
537 607
538<p> 608<p>
539Next to the <c>depend()</c> functionality, you also need to define the 609Next to the <c>depend()</c> functionality, you also need to define the
540<c>start()</c> function. This one contains all the commands necessary to 610<c>start()</c> function. This one contains all the commands necessary to
541initialise your service. It is adviseable to use the <c>ebegin</c> and 611initialize your service. It is advisable to use the <c>ebegin</c> and
542<c>eend</c> functions to inform the user about what is happening: 612<c>eend</c> functions to inform the user about what is happening:
543</p> 613</p>
544 614
545<pre caption="Example start() function"> 615<pre caption="Example start() function">
546start() { 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
547 ebegin "Starting my_service" 622 ebegin "Starting my_service"
548 start-stop-daemon --start --quiet --exec /path/to/my_service 623 start-stop-daemon --start --exec /path/to/my_service \
624 --pidfile /path/to/my_pidfile
549 eend $? 625 eend $?
550} 626}
551</pre> 627</pre>
552 628
553<p> 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>
554If you need more examples of the <c>start()</c> function, please read the source 655If you need more examples of the <c>start()</c> function, please read the
555code of the available init scripts in your <path>/etc/init.d</path> directory. 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 $?
693}
694</pre>
695
696<p>
556As for <c>start-stop-daemon</c>, there is an excellent man page available if you 697<c>start-stop-daemon</c> has an excellent man page available if you need more
557need more information: 698information:
558</p> 699</p>
559 700
560<pre caption="Getting the man page for start-stop-daemon"> 701<pre caption="Getting the man page for start-stop-daemon">
561# <i>man start-stop-daemon</i> 702$ <i>man start-stop-daemon</i>
562</pre> 703</pre>
563 704
564<p> 705<p>
565Other functions you can define are: <c>stop()</c> and <c>restart()</c>. You are 706Gentoo's init script syntax is based on the Bourne Again Shell (bash) so you are
566not obliged to define these functions! Our init system is intelligent enough to 707free to use bash-compatible constructs inside your init script. However, you may
567fill these functions in herself if you use <c>start-stop-daemon</c>. 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.
568</p> 712</p>
569 713
570</body> 714</body>
571</subsection> 715</subsection>
572<subsection> 716<subsection>
582 726
583<pre caption="Supporting the restartdelay option"> 727<pre caption="Supporting the restartdelay option">
584opts="${opts} restartdelay" 728opts="${opts} restartdelay"
585 729
586restartdelay() { 730restartdelay() {
587 stop() 731 stop
588 sleep 3 <comment># Wait 3 seconds before starting again</comment> 732 sleep 3 <comment># Wait 3 seconds before starting again</comment>
589 start() 733 start
590} 734}
591</pre> 735</pre>
736
737<impo>
738The function <c>restart()</c> cannot be overridden in openrc!
739</impo>
592 740
593</body> 741</body>
594</subsection> 742</subsection>
595<subsection> 743<subsection>
596<title>Service Configuration Variables</title> 744<title>Service Configuration Variables</title>
615</p> 763</p>
616 764
617</body> 765</body>
618</subsection> 766</subsection>
619</section> 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>
874
875</body>
876</subsection>
877</section>
620</sections> 878</sections>

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