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2<!DOCTYPE sections SYSTEM "/dtd/book.dtd"> 2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3 3
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7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.45 2007/02/20 22:07:04 nightmorph 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> 11<abstract>
12USE-flags are a very important aspect of Gentoo. In this chapter, you learn to 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. 13work with USE flags and understand how USE flags interact with your system.
14</abstract> 14</abstract>
15 15
16<version>1.36</version> 16<version>1.36</version>
17<date>2007-02-20</date> 17<date>2007-02-20</date>
18 18
19<section> 19<section>
20<title>What are USE-flags?</title> 20<title>What are USE flags?</title>
21<subsection> 21<subsection>
22<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE flags</title>
23<body> 23<body>
24 24
25<p> 25<p>
26When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
27system 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
32<p> 32<p>
33This 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
34what 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
35would 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
36packages? 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
37with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
38</p> 38</p>
39 39
40<p> 40<p>
41To 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
42user 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
45</p> 45</p>
46 46
47</body> 47</body>
48</subsection> 48</subsection>
49<subsection> 49<subsection>
50<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
51<body> 51<body>
52 52
53<p> 53<p>
54Enter 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
55dependency-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,
56Portage 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
57this also alters the dependency information for a package. 57this also alters the dependency information for a package.
58</p> 58</p>
59 59
60<p> 60<p>
73</p> 73</p>
74 74
75</body> 75</body>
76</subsection> 76</subsection>
77<subsection> 77<subsection>
78<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
79<body> 79<body>
80 80
81<p> 81<p>
82There 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.
83</p> 83</p>
84 84
85<ul> 85<ul>
86 <li> 86 <li>
87 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
88 what most people see as USE-flags. 88 what most people see as USE flags.
89 </li>
90 <li> 89 </li>
90 <li>
91 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
92 decisions. 92 decisions.
93 </li> 93 </li>
94</ul> 94</ul>
95 95
96<p> 96<p>
97A list of available global USE-flags can be found <uri 97A list of available global USE flags can be found <uri
98link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml">online</uri> or locally in
99<path>/usr/portage/profiles/use.desc</path>. 99<path>/usr/portage/profiles/use.desc</path>.
100</p> 100</p>
101 101
102<p> 102<p>
103A list of available local USE-flags can be found locally in 103A list of available local USE flags can be found locally in
104<path>/usr/portage/profiles/use.local.desc</path>. 104<path>/usr/portage/profiles/use.local.desc</path>.
105</p> 105</p>
106 106
107</body> 107</body>
108</subsection> 108</subsection>
109</section> 109</section>
110<section> 110<section>
111<title>Using USE-flags</title> 111<title>Using USE flags</title>
112<subsection> 112<subsection>
113<title>Declare permanent USE-flags</title> 113<title>Declare permanent USE flags</title>
114<body> 114<body>
115 115
116<p> 116<p>
117In 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
118you how to declare USE-flags. 118you how to declare USE flags.
119</p>
120
121<p> 119</p>
120
121<p>
122As 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>
123variable. 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
124provide 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
125we 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
126in the <path>make.defaults</path> files part of your profile. 126in the <path>make.defaults</path> files part of your profile.
127</p> 127</p>
128 128
129<p> 129<p>
155</p> 155</p>
156 156
157<p> 157<p>
158To 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
159<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
160in <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
161require, 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
162prefixing the keyword with the minus-sign ("-"). 162prefixing the keyword with the minus-sign ("-").
163</p> 163</p>
164 164
165<p> 165<p>
166For 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
203</pre> 203</pre>
204 204
205</body> 205</body>
206</subsection> 206</subsection>
207<subsection> 207<subsection>
208<title>Declare temporary USE-flags</title> 208<title>Declare temporary USE flags</title>
209<body> 209<body>
210 210
211<p> 211<p>
212Sometimes 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
213<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
214declare the USE-variable as environment variable. Remember that, when you 214declare the USE variable as environment variable. Remember that, when you
215re-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
216update) your changes will be lost! 216update) your changes will be lost!
217</p> 217</p>
218 218
219<p> 219<p>
220As an example we will temporarily remove java from the USE-setting 220As an example we will temporarily remove java from the USE setting
221during the installation of seamonkey. 221during the installation of seamonkey.
222</p> 222</p>
223 223
224<pre caption="Using USE as environment variable"> 224<pre caption="Using USE as environment variable">
225# <i>USE="-java" emerge seamonkey</i> 225# <i>USE="-java" emerge seamonkey</i>
314 314
315</body> 315</body>
316</subsection> 316</subsection>
317</section> 317</section>
318<section> 318<section>
319<title>Package specific USE-flags</title> 319<title>Package specific USE flags</title>
320<subsection> 320<subsection>
321<title>Viewing available USE-flags</title> 321<title>Viewing available USE flags</title>
322<body> 322<body>
323 323
324<p> 324<p>
325Let us take the example of <c>seamonkey</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
326find 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>
327options: 327options:
328</p> 328</p>
329 329
330<pre caption="Viewing the used USE-flags"> 330<pre caption="Viewing the used USE flags">
331# <i>emerge --pretend --verbose seamonkey</i> 331# <i>emerge --pretend --verbose seamonkey</i>
332These are the packages that I would merge, in order: 332These are the packages that I would merge, in order:
333 333
334Calculating dependencies ...done! 334Calculating dependencies ...done!
335[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6 335[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
346<pre caption="Installing gentoolkit"> 346<pre caption="Installing gentoolkit">
347# <i>emerge gentoolkit</i> 347# <i>emerge gentoolkit</i>
348</pre> 348</pre>
349 349
350<p> 350<p>
351Now 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
352certain package. For instance, for the <c>gnumeric</c> package: 352certain package. For instance, for the <c>gnumeric</c> package:
353</p> 353</p>
354 354
355<pre caption="Using equery to view used USE-flags"> 355<pre caption="Using equery to view used USE flags">
356# <i>equery uses =gnumeric-1.6.3 -a</i> 356# <i>equery uses =gnumeric-1.6.3 -a</i>
357[ Searching for packages matching =gnumeric-1.6.3... ] 357[ Searching for packages matching =gnumeric-1.6.3... ]
358[ Colour Code : <comment>set</comment> <i>unset</i> ] 358[ Colour Code : <comment>set</comment> <i>unset</i> ]
359[ Legend : Left column (U) - USE flags from make.conf ] 359[ Legend : Left column (U) - USE flags from make.conf ]
360[ : Right column (I) - USE flags packages was installed with ] 360[ : Right column (I) - USE flags packages was installed with ]

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