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Thu Nov 1 01:02:41 2007 UTC (10 years, 6 months ago) by yoswink
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Warn about setting doc USE flag globally (it's known to bring circular dependencies) and recommend doing it per package. Thanks to a random discussion on #-dev

1 <?xml version='1.0' encoding='UTF-8'?>
2 <!DOCTYPE sections SYSTEM "/dtd/book.dtd">
4 <!-- The content of this document is licensed under the CC-BY-SA license -->
5 <!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
7 <!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-portage.xml,v 1.65 2007/10/21 19:16:11 nightmorph Exp $ -->
9 <sections>
11 <abstract>
12 This chapter explains the "simple" steps a user definitely needs to know to
13 maintain the software on his system.
14 </abstract>
16 <version>1.60</version>
17 <date>2007-11-01</date>
19 <section>
20 <title>Welcome to Portage</title>
21 <body>
23 <p>
24 Portage is probably Gentoo's most notable innovation in software management.
25 With its high flexibility and enormous amount of features it is frequently seen
26 as the best software management tool available for Linux.
27 </p>
29 <p>
30 Portage is completely written in <uri link="http://www.python.org">Python</uri>
31 and <uri link="http://www.gnu.org/software/bash">Bash</uri> and therefore fully
32 visible to the users as both are scripting languages.
33 </p>
35 <p>
36 Most users will work with Portage through the <c>emerge</c> tool. This chapter
37 is not meant to duplicate the information available from the emerge man page.
38 For a complete rundown of emerge's options, please consult the man page:
39 </p>
41 <pre caption="Reading the emerge man page">
42 $ <i>man emerge</i>
43 </pre>
45 </body>
46 </section>
47 <section>
48 <title>The Portage Tree</title>
49 <subsection>
50 <title>Ebuilds</title>
51 <body>
53 <p>
54 When we talk about packages, we often mean software titles that are available to
55 the Gentoo users through the Portage tree. The Portage tree is a collection of
56 <e>ebuilds</e>, files that contain all information Portage needs to maintain
57 software (install, search, query, ...). These ebuilds reside in
58 <path>/usr/portage</path> by default.
59 </p>
61 <p>
62 Whenever you ask Portage to perform some action regarding software titles, it
63 will use the ebuilds on your system as a base. It is therefore important that
64 you regularly update the ebuilds on your system so Portage knows about new
65 software, security updates, etc.
66 </p>
68 </body>
69 </subsection>
70 <subsection>
71 <title>Updating the Portage Tree</title>
72 <body>
74 <p>
75 The Portage tree is usually updated with <uri
76 link="http://rsync.samba.org/">rsync</uri>, a fast incremental file transfer
77 utility. Updating is fairly simple as the <c>emerge</c> command provides a
78 front-end for rsync:
79 </p>
81 <pre caption="Updating the Portage tree">
82 # <i>emerge --sync</i>
83 </pre>
85 <p>
86 If you are unable to rsync due to firewall restrictions you can still update
87 your Portage tree by using our daily generated Portage tree snapshots. The
88 <c>emerge-webrsync</c> tool automatically fetches and installs the latest
89 snapshot on your system:
90 </p>
92 <pre caption="Running emerge-webrsync">
93 # <i>emerge-webrsync</i>
94 </pre>
96 </body>
97 </subsection>
98 </section>
99 <section>
100 <title>Maintaining Software</title>
101 <subsection>
102 <title>Searching for Software</title>
103 <body>
105 <p>
106 To search through the Portage tree after software titles, you can use
107 <c>emerge</c> built-in search capabilities. By default, <c>emerge --search</c>
108 returns the names of packages whose title matches (either fully or partially)
109 the given search term.
110 </p>
112 <p>
113 For instance, to search for all packages who have "pdf" in their name:
114 </p>
116 <pre caption="Searching for pdf-named packages">
117 $ <i>emerge --search pdf</i>
118 </pre>
120 <p>
121 If you want to search through the descriptions as well you can use the
122 <c>--searchdesc</c> (or <c>-S</c>) switch:
123 </p>
125 <pre caption="Searching for pdf-related packages">
126 $ <i>emerge --searchdesc pdf</i>
127 </pre>
129 <p>
130 When you take a look at the output, you'll notice that it gives you a lot of
131 information. The fields are clearly labelled so we won't go further into their
132 meanings:
133 </p>
135 <pre caption="Example 'emerge --search' output">
136 * net-print/cups-pdf
137 Latest version available: 1.5.2
138 Latest version installed: [ Not Installed ]
139 Size of downloaded files: 15 kB
140 Homepage: http://cip.physik.uni-wuerzburg.de/~vrbehr/cups-pdf/
141 Description: Provides a virtual printer for CUPS to produce PDF files.
142 License: GPL-2
143 </pre>
145 </body>
146 </subsection>
147 <subsection>
148 <title>Installing Software</title>
149 <body>
151 <p>
152 Once you've found a software title to your liking, you can easily install it
153 with <c>emerge</c>: just add the package name. For instance, to install
154 <c>gnumeric</c>:
155 </p>
157 <pre caption="Installing gnumeric">
158 # <i>emerge gnumeric</i>
159 </pre>
161 <p>
162 Since many applications depend on each other, any attempt to install a certain
163 software package might result in the installation of several dependencies as
164 well. Don't worry, Portage handles dependencies well. If you want to find out
165 what Portage <e>would</e> install when you ask it to install a certain package,
166 add the <c>--pretend</c> switch. For instance:
167 </p>
169 <pre caption="Pretend to install gnumeric">
170 # <i>emerge --pretend gnumeric</i>
171 </pre>
173 <p>
174 When you ask Portage to install a package, it will download the necessary source
175 code from the internet (if necessary) and store it by default in
176 <path>/usr/portage/distfiles</path>. After this it will unpack, compile and
177 install the package. If you want Portage to only download the sources without
178 installing them, add the <c>--fetchonly</c> option to the <c>emerge</c> command:
179 </p>
181 <pre caption="Download the sourcecode for gnumeric">
182 # <i>emerge --fetchonly gnumeric</i>
183 </pre>
185 </body>
186 </subsection>
187 <subsection>
188 <title>Finding Installed Package Documentation</title>
189 <body>
191 <p>
192 Many packages come with their own documentation. Sometimes, the <c>doc</c> USE
193 flag determines whether the package documentation should be installed or not.
194 You can check the existence of a <c>doc</c> USE flag with the <c>emerge -vp
195 &lt;package name&gt;</c> command.
196 </p>
198 <pre caption="Checking the existence of a doc USE flag">
199 <comment>(alsa-lib is just an example, of course.)</comment>
200 # <i>emerge -vp alsa-lib</i>
201 [ebuild N ] media-libs/alsa-lib-1.0.14_rc1 -debug +doc 698 kB
202 </pre>
204 <p>
205 The best way of enable the <c>doc</c> USE flag is doing it per package, in
206 <path>/etc/portage/package.use</path>, so you get documentation for the packages
207 you are interested in. Enable the flag globally is known to give problems with
208 circular dependencies. You can read the chapter about <uri
209 link="?part=2&amp;chap=2">USE Flags</uri> for more information about them.
210 </p>
212 <p>
213 Once the package installed, its documentation is generally found in a
214 subdirectory named after the package under the <path>/usr/share/doc</path>
215 directory. You can also list all installed files with the <c>equery</c> tool
216 which is part of the <c>app-portage/gentoolkit</c> <uri
217 link="/doc/en/gentoolkit.xml">package</uri>.
218 </p>
220 <pre caption="Locating package documentation">
221 # <i>ls -l /usr/share/doc/alsa-lib-1.0.14_rc1</i>
222 total 28
223 -rw-r--r-- 1 root root 669 May 17 21:54 ChangeLog.gz
224 -rw-r--r-- 1 root root 9373 May 17 21:54 COPYING.gz
225 drwxr-xr-x 2 root root 8560 May 17 21:54 html
226 -rw-r--r-- 1 root root 196 May 17 21:54 TODO.gz
228 <comment>(Alternatively, use equery to locate interesting files:)</comment>
229 # <i>equery files alsa-lib | less</i>
230 media-libs/alsa-lib-1.0.14_rc1
231 * Contents of media-libs/alsa-lib-1.0.14_rc1:
232 /usr
233 /usr/bin
234 /usr/bin/alsalisp
235 <comment>(Output truncated)</comment>
236 </pre>
238 </body>
239 </subsection>
240 <subsection>
241 <title>Removing Software</title>
242 <body>
244 <p>
245 When you want to remove a software package from your system, use <c>emerge
246 --unmerge</c>. This will tell Portage to remove all files installed by that
247 package from your system <e>except</e> the configuration files of that
248 application if you have altered those after the installation. Leaving the
249 configuration files allows you to continue working with the package if you ever
250 decide to install it again.
251 </p>
253 <p>
254 However, a <brite>big warning</brite> applies: Portage will <e>not</e> check if
255 the package you want to remove is required by another package. It will however
256 warn you when you want to remove an important package that breaks your system
257 if you unmerge it.
258 </p>
260 <pre caption="Removing gnumeric from the system">
261 # <i>emerge --unmerge gnumeric</i>
262 </pre>
264 <p>
265 When you remove a package from your system, the dependencies of that package
266 that were installed automatically when you installed the software are left. To
267 have Portage locate all dependencies that can now be removed, use
268 <c>emerge</c>'s <c>--depclean</c> functionality. We will talk about this later
269 on.
270 </p>
272 </body>
273 </subsection>
274 <subsection>
275 <title>Updating your System</title>
276 <body>
278 <p>
279 To keep your system in perfect shape (and not to mention install the latest
280 security updates) you need to update your system regularly. Since Portage only
281 checks the ebuilds in your Portage tree you first have to update your Portage
282 tree. When your Portage tree is updated, you can update your system with
283 <c>emerge --update world</c>. In the next example, we'll also use the
284 <c>--ask</c> switch which will tell Portage to display the list of packages it
285 wants to upgrade and ask you if you want to continue:
286 </p>
288 <pre caption="Updating your system">
289 # <i>emerge --update --ask world</i>
290 </pre>
292 <p>
293 Portage will then search for newer version of the applications you have
294 installed. However, it will only verify the versions for the applications you
295 have <e>explicitly</e> installed (the applications listed in
296 <path>/var/lib/portage/world</path>) - it does not thoroughly check their
297 dependencies. If you want to update <e>every single package</e> on your system,
298 add the <c>--deep</c> argument:
299 </p>
301 <pre caption="Updating your entire system">
302 # <i>emerge --update --deep world</i>
303 </pre>
305 <p>
306 Since security updates also happen in packages you have not explicitly installed
307 on your system (but that are pulled in as dependencies of other programs), it
308 is recommended to run this command once in a while.
309 </p>
311 <p>
312 If you have altered any of your <uri link="?part=2&amp;chap=2">USE flags</uri>
313 lately you might want to add <c>--newuse</c> as well. Portage will then verify
314 if the change requires the installation of new packages or recompilation of
315 existing ones:
316 </p>
318 <pre caption="Performing a full update">
319 # <i>emerge --update --deep --newuse world</i>
320 </pre>
322 </body>
323 </subsection>
324 <subsection>
325 <title>Metapackages</title>
326 <body>
328 <p>
329 Some packages in the Portage tree don't have any real content but are used to
330 install a collection of packages. For instance, the <c>kde</c> package will
331 install a complete KDE environment on your system by pulling in various
332 KDE-related packages as dependencies.
333 </p>
335 <p>
336 If you ever want to remove such a package from your system, running <c>emerge
337 --unmerge</c> on the package won't have much effect as the dependencies remain
338 on the system.
339 </p>
341 <p>
342 Portage has the functionality to remove orphaned dependencies as well, but since
343 the availability of software is dynamically dependent you first need to update
344 your entire system fully, including the new changes you applied when changing
345 USE flags. After this you can run <c>emerge --depclean</c> to remove the
346 orphaned dependencies. When this is done, you need to rebuild the applications
347 that were dynamically linked to the now-removed software titles but don't
348 require them anymore.
349 </p>
351 <p>
352 All this is handled with the following three commands:
353 </p>
355 <pre caption="Removing orphaned dependencies">
356 # <i>emerge --update --deep --newuse world</i>
357 # <i>emerge --depclean</i>
358 # <i>revdep-rebuild</i>
359 </pre>
361 <p>
362 <c>revdep-rebuild</c> is provided by the <c>gentoolkit</c> package; don't forget
363 to emerge it first:
364 </p>
366 <pre caption="Installing the gentoolkit package">
367 # <i>emerge gentoolkit</i>
368 </pre>
370 </body>
371 </subsection>
372 </section>
373 <section>
374 <title>When Portage is Complaining...</title>
375 <subsection>
376 <title>About SLOTs, Virtuals, Branches, Architectures and Profiles</title>
377 <body>
379 <p>
380 As we stated before, Portage is extremely powerful and supports many features
381 that other software management tools lack. To understand this, we explain a few
382 aspects of Portage without going into too much detail.
383 </p>
385 <p>
386 With Portage different versions of a single package can coexist on a system.
387 While other distributions tend to name their package to those versions (like
388 <c>freetype</c> and <c>freetype2</c>) Portage uses a technology called
389 <e>SLOT</e>s. An ebuild declares a certain SLOT for its version. Ebuilds with
390 different SLOTs can coexist on the same system. For instance, the
391 <c>freetype</c> package has ebuilds with <c>SLOT="1"</c> and <c>SLOT="2"</c>.
392 </p>
394 <p>
395 There are also packages that provide the same functionality but are implemented
396 differently. For instance, <c>metalogd</c>, <c>sysklogd</c> and <c>syslog-ng</c>
397 are all system loggers. Applications that rely on the availability of "a system
398 logger" cannot depend on, for instance, <c>metalogd</c>, as the other system
399 loggers are as good a choice as any. Portage allows for <e>virtuals</e>: each
400 system logger provides <c>virtual/syslog</c> so that applications can depend on
401 <c>virtual/syslog</c>.
402 </p>
404 <p>
405 Software in the Portage tree can reside in different branches. By default your
406 system only accepts packages that Gentoo deems stable. Most new software titles,
407 when committed, are added to the testing branch, meaning more testing needs to
408 be done before it is marked as stable. Although you will see the ebuilds for
409 those software in the Portage tree, Portage will not update them before they are
410 placed in the stable branch.
411 </p>
413 <p>
414 Some software is only available for a few architectures. Or the software doesn't
415 work on the other architectures, or it needs more testing, or the developer that
416 committed the software to the Portage tree is unable to verify if the package
417 works on different architectures.
418 </p>
420 <p>
421 Each Gentoo installation adheres to a certain <c>profile</c> which contains,
422 amongst other information, the list of packages that are required for a system
423 to function normally.
424 </p>
426 </body>
427 </subsection>
428 <subsection id="blocked">
429 <title>Blocked Packages</title>
430 <body>
432 <pre caption="Portage warning about blocked packages (with --pretend)">
433 [blocks B ] mail-mta/ssmtp (is blocking mail-mta/postfix-2.2.2-r1)
434 </pre>
436 <pre caption="Portage warning about blocked packages (without --pretend)">
437 !!! Error: the mail-mta/postfix package conflicts with another package.
438 !!! both can't be installed on the same system together.
439 !!! Please use 'emerge --pretend' to determine blockers.
440 </pre>
442 <p>
443 Ebuilds contain specific fields that inform Portage about its dependencies.
444 There are two possible dependencies: build dependencies, declared in
445 <c>DEPEND</c> and run-time dependencies, declared in <c>RDEPEND</c>. When one of
446 these dependencies explicitly marks a package or virtual as being <e>not</e>
447 compatible, it triggers a blockage.
448 </p>
450 <p>
451 To fix a blockage, you can choose to not install the package or unmerge the
452 conflicting package first. In the given example, you can opt not to install
453 <c>postfix</c> or to remove <c>ssmtp</c> first.
454 </p>
456 <p>
457 You may also see blocking packages with specific atoms, such as
458 <b>&lt;</b>media-video/mplayer-bin-1.0_rc1-r2. In this case, updating to a more
459 recent version of the blocking package would remove the block.
460 </p>
462 <p>
463 It is also possible that two packages that are yet to be installed are blocking
464 each other. In this rare case, you should find out why you need to install both.
465 In most cases you can do with one of the packages alone. If not, please file a
466 bug on <uri link="http://bugs.gentoo.org">Gentoo's bugtracking system</uri>.
467 </p>
469 </body>
470 </subsection>
471 <subsection id="masked">
472 <title>Masked Packages</title>
473 <body>
475 <pre caption="Portage warning about masked packages">
476 !!! all ebuilds that could satisfy "bootsplash" have been masked.
477 </pre>
479 <pre caption="Portage warning about masked packages - reason">
480 !!! possible candidates are:
482 - gnome-base/gnome-2.8.0_pre1 (masked by: <i>~x86 keyword</i>)
483 - lm-sensors/lm-sensors-2.8.7 (masked by: <i>-sparc keyword</i>)
484 - sys-libs/glibc- (masked by: <i>-* keyword</i>)
485 - dev-util/cvsd-1.0.2 (masked by: <i>missing keyword</i>)
486 - games-fps/unreal-tournament-451 (masked by: <i>package.mask</i>)
487 - sys-libs/glibc-2.3.2-r11 (masked by: <i>profile</i>)
488 </pre>
490 <p>
491 When you want to install a package that isn't available for your system, you
492 will receive this masking error. You should try installing a different
493 application that is available for your system or wait until the package is put
494 available. There is always a reason why a package is masked:
495 </p>
497 <ul>
498 <li>
499 <b>~arch keyword</b> means that the application is not tested sufficiently
500 to be put in the stable branch. Wait a few days or weeks and try again.
501 </li>
502 <li>
503 <b>-arch keyword</b> or <b>-* keyword</b> means that the application does
504 not work on your architecture. If you believe the package does work file
505 a bug at our <uri link="http://bugs.gentoo.org">bugzilla</uri> website.
506 </li>
507 <li>
508 <b>missing keyword</b> means that the application has not been tested on
509 your architecture yet. Ask the architecture porting team to test the package
510 or test it for them and report your findings on our <uri
511 link="http://bugs.gentoo.org">bugzilla</uri> website.
512 </li>
513 <li>
514 <b>package.mask</b> means that the package has been found corrupt, unstable
515 or worse and has been deliberately marked as do-not-use.
516 </li>
517 <li>
518 <b>profile</b> means that the package has been found not suitable for your
519 profile. The application might break your system if you installed it or is
520 just not compatible with the profile you use.
521 </li>
522 </ul>
524 </body>
525 </subsection>
526 <subsection id="missingdependencies">
527 <title>Missing Dependencies</title>
528 <body>
530 <pre caption="Portage warning about missing dependency">
531 emerge: there are no ebuilds to satisfy "&gt;=sys-devel/gcc-3.4.2-r4".
533 !!! Problem with ebuild sys-devel/gcc-3.4.2-r2
534 !!! Possibly a DEPEND/*DEPEND problem.
535 </pre>
537 <p>
538 The application you are trying to install depends on another package that is not
539 available for your system. Please check <uri
540 link="http://bugs.gentoo.org">bugzilla</uri> if the issue is known and if not,
541 please report it. Unless you are mixing branches this should not occur and is
542 therefore a bug.
543 </p>
545 </body>
546 </subsection>
547 <subsection id="ambiguousebuild">
548 <title>Ambiguous Ebuild Name</title>
549 <body>
551 <pre caption="Portage warning about ambiguous ebuild names">
552 !!! The short ebuild name "aterm" is ambiguous. Please specify
553 !!! one of the following fully-qualified ebuild names instead:
555 dev-libs/aterm
556 x11-terms/aterm
557 </pre>
559 <p>
560 The application you want to install has a name that corresponds with more than
561 one package. You need to supply the category name as well. Portage will inform
562 you of possible matches to choose from.
563 </p>
565 </body>
566 </subsection>
567 <subsection id="circulardependencies">
568 <title>Circular Dependencies</title>
569 <body>
571 <pre caption="Portage warning about circular dependencies">
572 !!! Error: circular dependencies:
574 ebuild / net-print/cups-1.1.15-r2 depends on ebuild / app-text/ghostscript-7.05.3-r1
575 ebuild / app-text/ghostscript-7.05.3-r1 depends on ebuild / net-print/cups-1.1.15-r2
576 </pre>
578 <p>
579 Two (or more) packages you want to install depend on each other and can
580 therefore not be installed. This is most likely a bug in the Portage tree.
581 Please resync after a while and try again. You can also check <uri
582 link="http://bugs.gentoo.org">bugzilla</uri> if the issue is known and if not,
583 report it.
584 </p>
586 </body>
587 </subsection>
588 <subsection id="fetchfailed">
589 <title>Fetch failed</title>
590 <body>
592 <pre caption="Portage warning about fetch failed">
593 !!! Fetch failed for sys-libs/ncurses-5.4-r5, continuing...
594 <comment>(...)</comment>
595 !!! Some fetch errors were encountered. Please see above for details.
596 </pre>
598 <p>
599 Portage was unable to download the sources for the given application and will
600 try to continue installing the other applications (if applicable). This failure
601 can be due to a mirror that has not synchronised correctly or because the ebuild
602 points to an incorrect location. The server where the sources reside can also be
603 down for some reason.
604 </p>
606 <p>
607 Retry after one hour to see if the issue still persists.
608 </p>
610 </body>
611 </subsection>
612 <subsection id="profileprotect">
613 <title>System Profile Protection</title>
614 <body>
616 <pre caption="Portage warning about profile-protected package">
617 !!! Trying to unmerge package(s) in system profile. 'sys-apps/portage'
618 !!! This could be damaging to your system.
619 </pre>
621 <p>
622 You have asked to remove a package that is part of your system's core packages.
623 It is listed in your profile as required and should therefore not be removed
624 from the system.
625 </p>
627 </body>
628 </subsection>
629 <subsection id="digesterror">
630 <title>Digest Verification Failures</title>
631 <body>
633 <p>
634 Sometimes, when you attempt to emerge a package, it will fail with the message:
635 </p>
637 <pre caption="Digest verification failure">
638 &gt;&gt;&gt; checking ebuild checksums
639 !!! Digest verification failed:
640 </pre>
642 <p>
643 This is a sign that something is wrong with the Portage tree -- often, it is
644 because a developer may have made a mistake when committing a package to the
645 tree.
646 </p>
648 <p>
649 When the digest verification fails, do <e>not</e> try to re-digest the package
650 yourself. Running <c>ebuild foo digest</c> will not fix the problem; it will
651 almost certainly make it worse!
652 </p>
654 <p>
655 Instead, wait an hour or two for the tree to settle down. It's likely that the
656 error was noticed right away, but it can take a little time for the fix to
657 trickle down the Portage tree. While you're waiting, check <uri
658 link="http://bugs.gentoo.org">Bugzilla</uri> and see if anyone has reported
659 the problem yet. If not, go ahead and file a bug for the broken package.
660 </p>
662 <p>
663 Once you see that the bug has been fixed, you may want to re-sync to pick up
664 the fixed digest.
665 </p>
667 <impo>
668 This does <e>not</e> mean that you can re-sync your tree multiple times! As
669 stated in the rsync policy (when you run <c>emerge --sync</c>), users who sync
670 too often will be banned! In fact, it's better to just wait until your next
671 scheduled sync, so that you don't overload the rsync servers.
672 </impo>
674 </body>
675 </subsection>
676 </section>
677 </sections>

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