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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 1.36 2005/10/26 14:37:18 rane Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.49 2007/10/21 19:16:11 nightmorph Exp $ -->
8 8
9<sections> 9<sections>
10 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
11<version>1.31</version> 16<version>1.38</version>
12<date>2005-10-26</date> 17<date>2007-10-21</date>
13 18
14<section> 19<section>
15<title>What are USE-flags?</title> 20<title>What are USE flags?</title>
16<subsection> 21<subsection>
17<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE flags</title>
18<body> 23<body>
19 24
20<p> 25<p>
21When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
22system 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
27<p> 32<p>
28This 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
29what 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
30would 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
31packages? 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
32with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
33</p> 38</p>
34 39
35<p> 40<p>
36To 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
37user 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
38deciding 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
39managment system, to make useful decisions. 44management system, to make useful decisions.
40</p> 45</p>
41 46
42</body> 47</body>
43</subsection>
44<subsection> 48</subsection>
49<subsection>
45<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
46<body> 51<body>
47 52
48<p> 53<p>
49Enter 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
50dependency-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,
51Portage 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
52this also alters the dependency information for a package. 57this also alters the dependency information for a package.
53</p> 58</p>
54 59
55<p> 60<p>
68</p> 73</p>
69 74
70</body> 75</body>
71</subsection> 76</subsection>
72<subsection> 77<subsection>
73<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
74<body> 79<body>
75 80
76<p> 81<p>
77There 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.
78</p> 83</p>
79 84
80<ul> 85<ul>
81 <li> 86 <li>
82 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
83 what most people see as USE-flags. 88 what most people see as USE flags.
84 </li>
85 <li> 89 </li>
90 <li>
86 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
87 decisions. 92 decisions.
88 </li> 93 </li>
89</ul> 94</ul>
90 95
91<p> 96<p>
92A list of available global USE-flags can be found <uri 97A list of available global USE flags can be found <uri
93link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml">online</uri> or locally in
94<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 99<path>/usr/portage/profiles/use.desc</path>.
95snippet:
96</p>
97
98<pre caption="A short snippet of available USE-flags">
99gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
100gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
101gtkhtml - Adds support for gnome-extra/gtkhtml
102guile - Adds support for dev-util/guile (interpreter for Scheme)
103icc - Use the Intel C++ Compiler if the package supports it
104icc-pgo - Enable PGO data generation or use when use icc.
105imap - Adds support for IMAP
106</pre>
107
108<p> 100</p>
101
102<p>
109A list of available local USE-flags can be found locally in 103A list of available local USE flags can be found locally in
110<path>/usr/portage/profiles/use.local.desc</path>. 104<path>/usr/portage/profiles/use.local.desc</path>.
111</p> 105</p>
112 106
113</body> 107</body>
114</subsection> 108</subsection>
115</section> 109</section>
116<section> 110<section>
117<title>Using USE-flags</title> 111<title>Using USE flags</title>
118<subsection> 112<subsection>
119<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
120<body> 114<body>
121 115
122<p> 116<p>
123In 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
124you how to declare USE-flags. 118you how to declare USE flags.
125</p>
126
127<p> 119</p>
120
121<p>
128As 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>
129variable. 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
130provide 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
131we 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
132in the <path>make.defaults</path> files part of your profile. 126in the <path>make.defaults</path> files part of your profile.
133</p> 127</p>
134 128
135<p> 129<p>
146 140
147<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile"> 141<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile">
148<comment>(This example is the sum of the settings in base, default-linux, 142<comment>(This example is the sum of the settings in base, default-linux,
149 default-linux/x86 and default-linux/x86/2004.3)</comment> 143 default-linux/x86 and default-linux/x86/2004.3)</comment>
150USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77 144USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77
151 foomaticdb gdbm gif gpm gtk gtk2 imlib jpeg kde gnome libg++ libwww mad 145 foomaticdb gdbm gif gpm gtk imlib jpeg kde gnome libg++ libwww mad
152 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt 146 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt
153 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib" 147 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
154</pre> 148</pre>
155 149
156<p> 150<p>
161</p> 155</p>
162 156
163<p> 157<p>
164To change this default setting, you need to add or remove keywords to the 158To change this default setting, you need to add or remove keywords to the
165<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable 159<c>USE</c> variable. This is done globally by defining the <c>USE</c> variable
166in <path>/etc/make.conf</path>. In this variable you add the extra USE-flags you 160in <path>/etc/make.conf</path>. In this variable you add the extra USE flags you
167require, or remove the USE-flags you don't want. This latter is done by 161require, or remove the USE flags you don't want. This latter is done by
168prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
169</p> 163</p>
170 164
171<p> 165<p>
172For instance, to remove support for KDE and QT but add support for ldap, the 166For instance, to remove support for KDE and QT but add support for ldap, the
173following <c>USE</c> can be defined in <path>/etc/make.conf</path>: 167following <c>USE</c> can be defined in <path>/etc/make.conf</path>:
174</p> 168</p>
175 169
176<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
177USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
178</pre> 172</pre>
179 173
180</body> 174</body>
181</subsection> 175</subsection>
182<subsection> 176<subsection>
185 179
186<p> 180<p>
187Sometimes you want to declare a certain USE flag for one (or a couple) of 181Sometimes you want to declare a certain USE flag for one (or a couple) of
188applications but not system-wide. To accomplish this, you will need to create 182applications but not system-wide. To accomplish this, you will need to create
189the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit 183the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
190<path>/etc/portage/package.use</path>. 184<path>/etc/portage/package.use</path>. This is usually a single file, but can
185also be a directory; see <c>man portage</c> for more information. The following
186examples assume <path>package.use</path> is a single file.
191</p> 187</p>
192 188
193<p> 189<p>
194For instance, if you don't want <c>berkdb</c> support globally but you do want 190For instance, if you don't want <c>berkdb</c> support globally but you do want
195it for <c>mysql</c>, you would add: 191it for <c>mysql</c>, you would add:
209</pre> 205</pre>
210 206
211</body> 207</body>
212</subsection> 208</subsection>
213<subsection> 209<subsection>
214<title>Declare temporary USE-flags</title> 210<title>Declare temporary USE flags</title>
215<body> 211<body>
216 212
217<p> 213<p>
218Sometimes you want to set a certain USE-setting only once. Instead of editing 214Sometimes you want to set a certain USE setting only once. Instead of editing
219<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 215<path>/etc/make.conf</path> twice (to do and undo the USE changes) you can just
220declare the USE-variable as environment variable. Remember that, when you 216declare the USE variable as environment variable. Remember that, when you
221re-emerge or update this application (either explicitly or as part of a system 217re-emerge or update this application (either explicitly or as part of a system
222update) your changes will be lost! 218update) your changes will be lost!
223</p> 219</p>
224 220
225<p> 221<p>
226As an example we will temporarily remove java from the USE-setting 222As an example we will temporarily remove java from the USE setting
227during the installation of mozilla. 223during the installation of seamonkey.
228</p> 224</p>
229 225
230<pre caption="Using USE as environment variable"> 226<pre caption="Using USE as environment variable">
231# <i>USE="-java" emerge mozilla</i> 227# <i>USE="-java" emerge seamonkey</i>
232</pre>
233
234</body>
235</subsection>
236<subsection>
237<title>Automatic USE Flags</title>
238<body>
239
240<p>
241After certain packages are installed, additional USE flags will automatically
242be enabled for you if you do not explicitly disable them. To view the list
243of packages that trigger automatic USE-flags, check
244<path>/etc/make.profile/use.defaults</path> and the <path>use.defaults</path>
245files of the parent profiles.
246</p>
247
248<pre caption="A snippet from /etc/make.profile/use.defaults">
249gnome gnome-base/gnome
250gtk x11-libs/gtk+
251qt x11-libs/qt
252kde kde-base/kdebase
253motif x11-libs/openmotif
254</pre> 228</pre>
255 229
256</body> 230</body>
257</subsection> 231</subsection>
258<subsection> 232<subsection>
269 243
270<ol> 244<ol>
271 <li> 245 <li>
272 Default USE setting declared in the <path>make.defaults</path> files part of 246 Default USE setting declared in the <path>make.defaults</path> files part of
273 your profile 247 your profile
274 </li>
275 <li>
276 Inherited USE setting if a package from profile <path>use.defaults</path> is installed
277 </li> 248 </li>
278 <li> 249 <li>
279 User-defined USE setting in <path>/etc/make.conf</path> 250 User-defined USE setting in <path>/etc/make.conf</path>
280 </li> 251 </li>
281 <li> 252 <li>
345 316
346</body> 317</body>
347</subsection> 318</subsection>
348</section> 319</section>
349<section> 320<section>
350<title>Package specific USE-flags</title> 321<title>Package specific USE flags</title>
351<subsection> 322<subsection>
352<title>Viewing available USE-flags</title> 323<title>Viewing available USE flags</title>
353<body> 324<body>
354 325
355<p> 326<p>
356Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 327Let us take the example of <c>seamonkey</c>: what USE flags does it listen to? To
357find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c> 328find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
358options: 329options:
359</p> 330</p>
360 331
361<pre caption="Viewing the used USE-flags"> 332<pre caption="Viewing the used USE flags">
362# <i>emerge --pretend --verbose mozilla</i> 333# <i>emerge --pretend --verbose seamonkey</i>
363These are the packages that I would merge, in order: 334These are the packages that I would merge, in order:
364 335
365Calculating dependencies ...done! 336Calculating dependencies ...done!
366[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 337[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
367+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 338-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
368-moznocompose -moznoxft 339-moznoroaming -postgres -xinerama -xprint" 0 kB
369</pre> 340</pre>
370 341
371<p> 342<p>
372<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 343<c>emerge</c> isn't the only tool for this job. In fact, we have a tool
373dedicated to package information called <c>equery</c> which resides in the 344dedicated to package information called <c>equery</c> which resides in the
377<pre caption="Installing gentoolkit"> 348<pre caption="Installing gentoolkit">
378# <i>emerge gentoolkit</i> 349# <i>emerge gentoolkit</i>
379</pre> 350</pre>
380 351
381<p> 352<p>
382Now run <c>equery</c> with the <c>uses</c> argument to view the USE-flags of a 353Now run <c>equery</c> with the <c>uses</c> argument to view the USE flags of a
383certain package. For instance, for the <c>gnumeric</c> package: 354certain package. For instance, for the <c>gnumeric</c> package:
384</p> 355</p>
385 356
386<pre caption="Using equery to view used USE-flags"> 357<pre caption="Using equery to view used USE flags">
387# <i>equery uses gnumeric</i> 358# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
388[ Colour Code : <i>set</i> <comment>unset</comment> ] 359[ Searching for packages matching =gnumeric-1.6.3... ]
389[ Legend : (U) Col 1 - Current USE flags ] 360[ Colour Code : set unset ]
390[ : (I) Col 2 - Installed With USE flags ] 361[ Legend : Left column (U) - USE flags from make.conf ]
391 362[ : Right column (I) - USE flags packages was installed with ]
392 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 363[ Found these USE variables for app-office/gnumeric-1.6.3 ]
393 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 364 U I
394 - - <comment>gnomedb</comment> : unknown 365 - - debug : Enable extra debug codepaths, like asserts and extra output.
366 If you want to get meaningful backtraces see
367 http://www.gentoo.org/proj/en/qa/backtraces.xml .
368 + + gnome : Adds GNOME support
395 + + <i>python</i> : Adds support/bindings for the Python language 369 + + python : Adds support/bindings for the Python language
396 + + <i>bonobo</i> : Adds support for gnome-base/bonobo (Gnome CORBA interfaces) 370 - - static : !!do not set this during bootstrap!! Causes binaries to be
371 statically linked instead of dynamically
397</pre> 372</pre>
398 373
399</body> 374</body>
400</subsection> 375</subsection>
401</section> 376</section>

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