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7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.42 2006/09/04 11:29:36 rane Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.46 2007/04/14 03:09:30 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>1.34</version> 16<version>1.36</version>
12<date>2006-09-03</date> 17<date>2007-02-20</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
40</p> 45</p>
41 46
42</body> 47</body>
43</subsection> 48</subsection>
44<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>. 99<path>/usr/portage/profiles/use.desc</path>.
95</p> 100</p>
96 101
97<p> 102<p>
98A list of available local USE-flags can be found locally in 103A list of available local USE flags can be found locally in
99<path>/usr/portage/profiles/use.local.desc</path>. 104<path>/usr/portage/profiles/use.local.desc</path>.
100</p> 105</p>
101 106
102</body> 107</body>
103</subsection> 108</subsection>
104</section> 109</section>
105<section> 110<section>
106<title>Using USE-flags</title> 111<title>Using USE flags</title>
107<subsection> 112<subsection>
108<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
109<body> 114<body>
110 115
111<p> 116<p>
112In 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
113you how to declare USE-flags. 118you how to declare USE flags.
114</p>
115
116<p> 119</p>
120
121<p>
117As 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>
118variable. 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
119provide 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
120we 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
121in the <path>make.defaults</path> files part of your profile. 126in the <path>make.defaults</path> files part of your profile.
122</p> 127</p>
123 128
124<p> 129<p>
150</p> 155</p>
151 156
152<p> 157<p>
153To 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
154<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
155in <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
156require, 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
157prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
158</p> 163</p>
159 164
160<p> 165<p>
161For 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
162following <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>:
163</p> 168</p>
164 169
165<pre caption="An example USE setting in /etc/make.conf"> 170<pre caption="An example USE setting in /etc/make.conf">
166USE="-kde -qt ldap" 171USE="-kde -qt3 -qt4 ldap"
167</pre> 172</pre>
168 173
169</body> 174</body>
170</subsection> 175</subsection>
171<subsection> 176<subsection>
198</pre> 203</pre>
199 204
200</body> 205</body>
201</subsection> 206</subsection>
202<subsection> 207<subsection>
203<title>Declare temporary USE-flags</title> 208<title>Declare temporary USE flags</title>
204<body> 209<body>
205 210
206<p> 211<p>
207Sometimes you want to set a certain USE-setting only once. Instead of editing 212Sometimes you want to set a certain USE setting only once. Instead of editing
208<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 213<path>/etc/make.conf</path> twice (to do and undo the USE changes) you can just
209declare the USE-variable as environment variable. Remember that, when you 214declare the USE variable as environment variable. Remember that, when you
210re-emerge or update this application (either explicitly or as part of a system 215re-emerge or update this application (either explicitly or as part of a system
211update) your changes will be lost! 216update) your changes will be lost!
212</p> 217</p>
213 218
214<p> 219<p>
215As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE setting
216during the installation of mozilla. 221during the installation of seamonkey.
217</p> 222</p>
218 223
219<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
220# <i>USE="-java" emerge mozilla</i> 225# <i>USE="-java" emerge seamonkey</i>
221</pre> 226</pre>
222 227
223</body> 228</body>
224</subsection> 229</subsection>
225<subsection> 230<subsection>
309 314
310</body> 315</body>
311</subsection> 316</subsection>
312</section> 317</section>
313<section> 318<section>
314<title>Package specific USE-flags</title> 319<title>Package specific USE flags</title>
315<subsection> 320<subsection>
316<title>Viewing available USE-flags</title> 321<title>Viewing available USE flags</title>
317<body> 322<body>
318 323
319<p> 324<p>
320Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 325Let us take the example of <c>seamonkey</c>: what USE flags does it listen to? To
321find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c> 326find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
322options: 327options:
323</p> 328</p>
324 329
325<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE flags">
326# <i>emerge --pretend --verbose mozilla</i> 331# <i>emerge --pretend --verbose seamonkey</i>
327These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
328 333
329Calculating dependencies ...done! 334Calculating dependencies ...done!
330[ebuild R ] www-client/mozilla-1.7.12-r2 USE="crypt gnome java mozsvg ssl 335[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
331truetype xprint -debug -ipv6 -ldap -mozcalendar -mozdevelop -moznocompose 336-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
332-moznoirc -moznomail -moznoxft -postgres -xinerama" 0 kB 337-moznoroaming -postgres -xinerama -xprint" 0 kB
333</pre> 338</pre>
334 339
335<p> 340<p>
336<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 341<c>emerge</c> isn't the only tool for this job. In fact, we have a tool
337dedicated to package information called <c>equery</c> which resides in the 342dedicated to package information called <c>equery</c> which resides in the
341<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
342# <i>emerge gentoolkit</i> 347# <i>emerge gentoolkit</i>
343</pre> 348</pre>
344 349
345<p> 350<p>
346Now run <c>equery</c> with the <c>uses</c> argument to view the USE-flags of a 351Now run <c>equery</c> with the <c>uses</c> argument to view the USE flags of a
347certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
348</p> 353</p>
349 354
350<pre caption="Using equery to view used USE-flags"> 355<pre caption="Using equery to view used USE flags">
351# <i>equery uses =gnumeric-1.6.3 -a</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
352[ Searching for packages matching =gnumeric-1.6.3... ] 357[ Searching for packages matching =gnumeric-1.6.3... ]
353[ Colour Code : <comment>set</comment> <i>unset</i> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
354[ Legend : Left column (U) - USE flags from make.conf ] 359[ Legend : Left column (U) - USE flags from make.conf ]
355[ : Right column (I) - USE flags packages was installed with ] 360[ : Right column (I) - USE flags packages was installed with ]

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