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1<?xml version='1.0' encoding='UTF-8'?> 1<?xml version='1.0' encoding='UTF-8'?>
2<!DOCTYPE sections SYSTEM "/dtd/book.dtd"> 2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3 3
4<!-- The content of this document is licensed under the CC-BY-SA license --> 4<!-- The content of this document is licensed under the CC-BY-SA license -->
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6 6
7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.16 2004/07/07 19:19:26 neysx Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.53 2013/02/09 08:46:08 swift Exp $ -->
8 8
9<sections> 9<sections>
10
11<abstract>
12USE flags are a very important aspect of Gentoo. In this chapter, you learn to
13work with USE flags and understand how USE flags interact with your system.
14</abstract>
15
16<version>4</version>
17<date>2013-02-09</date>
18
10<section> 19<section>
11<title>What are USE-flags?</title> 20<title>What are USE flags?</title>
12<subsection> 21<subsection>
13<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE flags</title>
14<body> 23<body>
15 24
16<p> 25<p>
17When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
18system for that matter) you make choices depending on the environment you are 27system for that matter) you make choices depending on the environment you are
23<p> 32<p>
24This is not only true for choosing what packages you want to install, but also 33This is not only true for choosing what packages you want to install, but also
25what features a certain package should support. If you don't need OpenGL, why 34what features a certain package should support. If you don't need OpenGL, why
26would you bother installing OpenGL and build OpenGL support in most of your 35would you bother installing OpenGL and build OpenGL support in most of your
27packages? If you don't want to use KDE, why would you bother compiling packages 36packages? If you don't want to use KDE, why would you bother compiling packages
28with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
29</p> 38</p>
30 39
31<p> 40<p>
32To help users in deciding what to install/activate and what not, we wanted the 41To help users in deciding what to install/activate and what not, we wanted the
33user to specify his/her environment in an easy way. This forces the user into 42user to specify his/her environment in an easy way. This forces the user into
34deciding what they really want and eases the process for Portage, our package 43deciding what they really want and eases the process for Portage, our package
35managment system, to make useful decisions. 44management system, to make useful decisions.
36</p> 45</p>
37 46
38</body> 47</body>
39</subsection>
40<subsection> 48</subsection>
49<subsection>
41<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
42<body> 51<body>
43 52
44<p> 53<p>
45Enter the USE-flags. Such a flag is a keyword that embodies support and 54Enter the USE flags. Such a flag is a keyword that embodies support and
46dependency-information for a certain concept. If you define a certain USE-flag, 55dependency-information for a certain concept. If you define a certain USE flag,
47Portage will know that you want support for the chosen keyword. Of course 56Portage will know that you want support for the chosen keyword. Of course
48this also alters the dependency information for a package. 57this also alters the dependency information for a package.
49</p> 58</p>
50 59
51<p> 60<p>
64</p> 73</p>
65 74
66</body> 75</body>
67</subsection> 76</subsection>
68<subsection> 77<subsection>
69<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
70<body> 79<body>
71 80
72<p> 81<p>
73There are two types of USE-flags: <e>global</e> and <e>local</e> USE-flags. 82There are two types of USE flags: <e>global</e> and <e>local</e> USE flags.
74</p> 83</p>
75 84
76<ul> 85<ul>
77 <li> 86 <li>
78 A <e>global</e> USE-flag is used by several packages, system-wide. This is 87 A <e>global</e> USE flag is used by several packages, system-wide. This is
79 what most people see as USE-flags. 88 what most people see as USE flags.
80 </li>
81 <li> 89 </li>
90 <li>
82 A <e>local</e> USE-flag is used by a single package to make package-specific 91 A <e>local</e> USE flag is used by a single package to make package-specific
83 decisions. 92 decisions.
84 </li> 93 </li>
85</ul> 94</ul>
86 95
87<p> 96<p>
88A list of available global USE-flags can be found <uri 97A list of available global USE flags can be found <uri
89link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml">online</uri> or locally in
90<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 99<path>/usr/portage/profiles/use.desc</path>.
91snippet: 100</p>
101
92</p> 102<p>
93 103A list of available local USE flags can be found locally in
94<pre caption="A short snippet of available USE-flags"> 104<path>/usr/portage/profiles/use.local.desc</path>.
95gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
96gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
97gtkhtml - Adds support for gnome-extra/gtkhtml
98guile - Adds support for dev-util/guile (interpreter for Scheme)
99icc - Use the Intel C++ Compiler if the package supports it
100icc-pgo - Enable PGO data generation or use when use icc.
101imap - Adds support for IMAP
102</pre> 105</p>
103 106
104</body> 107</body>
105</subsection> 108</subsection>
106</section> 109</section>
107<section> 110<section>
108<title>Using USE-flags</title> 111<title>Using USE flags</title>
109<subsection> 112<subsection>
110<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
111<body> 114<body>
112 115
113<p> 116<p>
114In the hope you are convinced of the importance of USE-flags we will now inform 117In the hope you are convinced of the importance of USE flags we will now inform
115you how to declare USE-flags. 118you how to declare USE flags.
116</p>
117
118<p> 119</p>
120
121<p>
119As previously mentioned, all USE-flags are declared inside the <c>USE</c> 122As previously mentioned, all USE flags are declared inside the <c>USE</c>
120variable. To make it easy for users to search and pick USE-flags, we already 123variable. To make it easy for users to search and pick USE flags, we already
121provide a <e>default</e> USE setting. This setting is a collection of USE-flags 124provide a <e>default</e> USE setting. This setting is a collection of USE flags
122we think are commonly used by the Gentoo users. This default setting is declared 125we think are commonly used by the Gentoo users. This default setting is declared
123in the <path>/etc/make.profile/make.defaults</path> file. Let us take a look at 126in the <path>make.defaults</path> files part of your profile.
124this default setting: 127</p>
128
125</p> 129<p>
130The profile your system listens to is pointed to by the
131<path>/etc/portage/make.profile</path> symlink. Each profile works on top of
132another, larger profile, the end result is therefore the sum of all profiles.
133The top profile is the <path>base</path> profile
134(<path>/usr/portage/profiles/base</path>).
135</p>
126 136
127<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 137<p>
128USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 138Let us take a look at this default setting for the 13.0 profile:
129 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 139</p>
130 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 140
131 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 141<pre caption="Cumulative make.defaults USE variable for the 13.0 profile">
142<comment>(This example is the sum of the settings in base, default/linux,
143 default/linux/x86 and default/linux/x86/13.0/)</comment>
144USE="a52 aac acpi alsa branding cairo cdr dbus dts dvd dvdr emboss encode exif
145fam firefox flac gif gpm gtk hal jpeg lcms ldap libnotify mad mikmod mng mp3
146mp4 mpeg ogg opengl pango pdf png ppds qt3support qt4 sdl spell
147startup-notification svg tiff truetype vorbis unicode usb X xcb x264 xml xv
148xvid"
132</pre> 149</pre>
133 150
134<p> 151<p>
135As you can see, this variable already contains quite a lot of keywords. Do 152As you can see, this variable already contains quite a lot of keywords. Do
136<b>not</b> alter the <path>/etc/make.profile/make.defaults</path> file to tailor 153<b>not</b> alter any <path>make.defaults</path> file to tailor
137the <c>USE</c> variable to your needs: changes in this file will be undone when 154the <c>USE</c> variable to your needs: changes in this file will be undone when
138you update Portage! 155you update Portage!
139</p> 156</p>
140 157
141<p> 158<p>
142To change this default setting, you need to add or remove keywords to the 159To change this default setting, you need to add or remove keywords to the
143<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable 160<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable
144in <path>/etc/make.conf</path>. In this variable you add the extra USE-flags you 161in <path>/etc/portage/make.conf</path>. In this variable you add the extra USE
145require, or remove the USE-flags you don't want. This latter is done by 162flags you require, or remove the USE flags you don't want. This latter is done
146prefixing the keyword with the minus-sign ("-"). 163by prefixing the keyword with the minus-sign ("-").
147</p> 164</p>
148 165
149<p> 166<p>
150For instance, to remove support for KDE and QT but add support for ldap, the 167For instance, to remove support for KDE and QT but add support for ldap, the
151following <c>USE</c> can be defined in <path>/etc/make.conf</path>: 168following <c>USE</c> can be defined in <path>/etc/portage/make.conf</path>:
152</p> 169</p>
153 170
154<pre caption="An example USE setting in /etc/make.conf"> 171<pre caption="An example USE setting in /etc/portage/make.conf">
155USE="-kde -qt ldap" 172USE="-kde -qt4 ldap"
156</pre> 173</pre>
157 174
158</body> 175</body>
159</subsection>
160<subsection> 176</subsection>
177<subsection>
178<title>Declaring USE flags for individual packages</title>
179<body>
180
181<p>
182Sometimes you want to declare a certain USE flag for one (or a couple) of
183applications but not system-wide. To accomplish this, you will need to create
184the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
185<path>/etc/portage/package.use</path>. This is usually a single file, but can
186also be a directory; see <c>man portage</c> for more information. The following
187examples assume <path>package.use</path> is a single file.
188</p>
189
190<p>
191For instance, if you don't want <c>berkdb</c> support globally but you do want
192it for <c>mysql</c>, you would add:
193</p>
194
195<pre caption="/etc/portage/package.use example">
196dev-db/mysql berkdb
197</pre>
198
199<p>
200You can of course also explicitly <e>disable</e> USE flags for a certain
201application. For instance, if you don't want <c>java</c> support in PHP:
202</p>
203
204<pre caption="/etc/portage/package.use 2nd example">
205dev-php/php -java
206</pre>
207
208</body>
209</subsection>
210<subsection>
161<title>Declare temporary USE-flags</title> 211<title>Declare temporary USE flags</title>
162<body> 212<body>
163 213
164<p> 214<p>
165Sometimes you want to set a certain USE-setting only once. Instead of editing 215Sometimes you want to set a certain USE setting only once. Instead of editing
166<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 216<path>/etc/portage/make.conf</path> twice (to do and undo the USE changes) you
167declare the USE-variable as environment variable. 217can just declare the USE variable as environment variable. Remember that, when
168</p> 218you re-emerge or update this application (either explicitly or as part of a
169 219system update) your changes will be lost!
170<p> 220</p>
221
222<p>
171As an example we will temporarily remove java from the USE-setting 223As an example we will temporarily remove java from the USE setting
172during the installation of mozilla. 224during the installation of seamonkey.
173</p> 225</p>
174
175<note>
176The <c>emerge</c> command will be discussed more thoroughly in <uri
177link="?part=2&amp;chap=2">Portage and Software</uri>.
178</note>
179 226
180<pre caption="Using USE as environment variable"> 227<pre caption="Using USE as environment variable">
181# <i>USE="-java" emerge mozilla</i> 228# <i>USE="-java" emerge seamonkey</i>
182</pre>
183
184</body>
185</subsection>
186<subsection>
187<title>Inheriting USE-flags</title>
188<body>
189
190<p>
191Some packages don't only listen to USE-flags, but also provide USE-flags. When
192you install such a package, the USE-flag they provide is added to your USE
193setting. To view the list of packages that provide a USE-flag, check
194<path>/etc/make.profile/use.defaults</path>:
195</p>
196
197<pre caption="A snippet from /etc/make.profile/use.defaults">
198gnome gnome-base/gnome
199gtk x11-libs/gtk+
200qt x11-libs/qt
201kde kde-base/kdebase
202motif x11-libs/openmotif
203</pre> 229</pre>
204 230
205</body> 231</body>
206</subsection> 232</subsection>
207<subsection> 233<subsection>
208<title>Precedence</title> 234<title>Precedence</title>
209<body> 235<body>
210 236
211<p> 237<p>
212Of course there is a certain precedence on what setting has priority over the 238Of course there is a certain precedence on what setting has priority over the
213USE setting. You don't want to declare <c>USE="-java"</c> only to see that 239USE setting. You don't want to declare <c>USE="-java"</c> only to see that
214<c>java</c> is declared anyway. The precedence for the USE setting is, ordered 240<c>java</c> is still used due to a setting that has a higher priority.
241The precedence for the USE setting is, ordered
215by priority (first has lowest priority): 242by priority (first has lowest priority):
216</p> 243</p>
217 244
218<ol> 245<ol>
219 <li> 246 <li>
220 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 247 Default USE setting declared in the <path>make.defaults</path> files part of
221 </li> 248 your profile
222 <li> 249 </li>
223 Inherited USE setting if a package from
224 <path>/etc/make.profile/use.defaults</path> is installed
225 </li> 250 <li>
226 <li>
227 User-defined USE setting in <path>/etc/make.conf</path> 251 User-defined USE setting in <path>/etc/portage/make.conf</path>
252 </li>
253 <li>
254 User-defined USE setting in <path>/etc/portage/package.use</path>
228 </li> 255 </li>
229 <li> 256 <li>
230 User-defined USE setting as environment variable 257 User-defined USE setting as environment variable
231 </li> 258 </li>
232</ol> 259</ol>
233 260
234<p> 261<p>
235To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 262To view the final <c>USE</c> setting as seen by Portage, run <c>emerge
236This will list all relevant variables (including the <c>USE</c> variable) with 263--info</c>. This will list all relevant variables (including the <c>USE</c>
237the content used by Portage. 264variable) with the content used by Portage.
238</p> 265</p>
239 266
240<pre caption="Running emerge info"> 267<pre caption="Running emerge --info">
241# <i>emerge info</i> 268# <i>emerge --info</i>
242</pre> 269</pre>
243 270
244</body> 271</body>
245</subsection> 272</subsection>
246<subsection> 273<subsection>
247<title>Adapting your Entire System to New USE Flags</title> 274<title>Adapting your Entire System to New USE Flags</title>
248<body> 275<body>
249 276
250<p> 277<p>
251If you have altered your USE flags and you wish to update your entire system to 278If you have altered your USE flags and you wish to update your entire system to
252use the new USE flags, you can try following the next steps to accomplish this. 279use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
253Note however that these steps will take a long time to finish and that work is
254on the way to adjust Portage to handle this behaviour quicker and automatically.
255</p>
256
257<p>
258First of all, rebuild your entire system using the new USE flags:
259</p> 280</p>
260 281
261<pre caption="Rebuilding your entire system"> 282<pre caption="Rebuilding your entire system">
262# <i>emerge --emptytree world</i> 283# <i>emerge --update --deep --newuse world</i>
263</pre> 284</pre>
264 285
265<p> 286<p>
266Next, run Portage' depclean to remove the conditional dependencies that 287Next, run Portage's depclean to remove the conditional dependencies that
267were emerged on your "old" system but that have been obsoleted by the new USE 288were emerged on your "old" system but that have been obsoleted by the new USE
268flags. 289flags.
269</p> 290</p>
270 291
271<warn> 292<warn>
272Running <c>emerge depclean</c> is a dangerous operation and should be handled 293Running <c>emerge --depclean</c> is a dangerous operation and should be handled
273with care. Double-check the provided list of "obsoleted" packages to make sure 294with care. Double-check the provided list of "obsoleted" packages to make sure
274it doesn't remove packages you need. In the following example we add the 295it doesn't remove packages you need. In the following example we add the
275<c>-p</c> switch to have depclean only list the packages without removing them. 296<c>-p</c> switch to have depclean only list the packages without removing them.
276</warn> 297</warn>
277 298
278<pre caption="Removing obsoleted packages"> 299<pre caption="Removing obsoleted packages">
279# <i>emerge -p depclean</i> 300# <i>emerge -p --depclean</i>
280</pre> 301</pre>
281 302
303<p>
304When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
305applications that are dynamically linked against shared objects provided by
306possibly removed packages. <c>revdep-rebuild</c> is part of the
307<c>gentoolkit</c> package; don't forget to emerge it first.
282<p> 308</p>
309
310<pre caption="Running revdep-rebuild">
311# <i>revdep-rebuild</i>
312</pre>
313
314<p>
283When depclean has finished, your system is using the new USE flag settings. 315When all this is accomplished, your system is using the new USE flag settings.
284</p> 316</p>
285 317
286</body> 318</body>
287</subsection> 319</subsection>
288</section> 320</section>
289<section> 321<section>
290<title>Package specific USE-flags</title> 322<title>Package specific USE flags</title>
291<subsection> 323<subsection>
292<title>Viewing available USE-flags</title> 324<title>Viewing available USE flags</title>
293<body> 325<body>
294 326
295<p>
296In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
297we will explain how to manage your installed software and how to work with
298<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
299you how to view what USE-flags a package uses.
300</p> 327<p>
301
302<p>
303Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 328Let us take the example of <c>seamonkey</c>: what USE flags does it listen to? To
304find out, we use <c>emerge</c> with the <c>--pretend</c> (don't really do 329find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
305anything) and <c>--verbose</c> (give more output) options: 330options:
306</p> 331</p>
307 332
308<pre caption="Viewing the used USE-flags"> 333<pre caption="Viewing the used USE flags">
309# <i>emerge --pretend --verbose mozilla</i> 334# <i>emerge --pretend --verbose seamonkey</i>
310These are the packages that I would merge, in order: 335These are the packages that I would merge, in order:
311 336
312Calculating dependencies ...done! 337Calculating dependencies ...done!
313[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 338[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
314+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 339-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
315-moznocompose -moznoxft 340-moznoroaming -postgres -xinerama -xprint" 0 kB
316</pre> 341</pre>
317 342
318<p> 343<p>
319<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 344<c>emerge</c> isn't the only tool for this job. In fact, we have a tool
320dedicated to package information called <c>etcat</c> which resides in the 345dedicated to package information called <c>equery</c> which resides in the
321<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 346<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
322</p> 347</p>
323 348
324<pre caption="Installing gentoolkit"> 349<pre caption="Installing gentoolkit">
325# <i>emerge --usepkg gentoolkit</i> 350# <i>emerge gentoolkit</i>
326</pre> 351</pre>
327 352
328<p> 353<p>
329Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 354Now run <c>equery</c> with the <c>uses</c> argument to view the USE flags of a
330certain package. For instance, for the <c>gnumeric</c> package: 355certain package. For instance, for the <c>gnumeric</c> package:
331</p> 356</p>
332 357
333<pre caption="Using etcat to view used USE-flags"> 358<pre caption="Using equery to view used USE flags">
334# <i>etcat uses gnumeric</i> 359# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
335[ Colour Code : <i>set</i> <comment>unset</comment> ] 360[ Searching for packages matching =gnumeric-1.6.3... ]
336[ Legend : (U) Col 1 - Current USE flags ] 361[ Colour Code : set unset ]
337[ : (I) Col 2 - Installed With USE flags ] 362[ Legend : Left column (U) - USE flags from make.conf ]
338 363[ : Right column (I) - USE flags packages was installed with ]
339 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 364[ Found these USE variables for app-office/gnumeric-1.6.3 ]
340 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 365 U I
341 - - <comment>gnomedb</comment> : unknown 366 - - debug : Enable extra debug codepaths, like asserts and extra output.
367 If you want to get meaningful backtraces see
368 http://www.gentoo.org/proj/en/qa/backtraces.xml .
369 + + gnome : Adds GNOME support
342 + + <i>python</i> : Adds support/bindings for the Python language 370 + + python : Adds support/bindings for the Python language
343 + + <i>bonobo</i> : Adds support for gnome-base/bonobo (Gnome CORBA interfaces) 371 - - static : !!do not set this during bootstrap!! Causes binaries to be
372 statically linked instead of dynamically
344</pre> 373</pre>
345 374
346</body> 375</body>
347</subsection> 376</subsection>
348</section> 377</section>

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