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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 -->
5<!-- See http://creativecommons.org/licenses/by-sa/1.0 --> 5<!-- See http://creativecommons.org/licenses/by-sa/2.5 -->
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 1.54 2013/07/23 20:14:45 swift 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>5</version>
12<date>2005-10-26</date> 17<date>2013-07-23</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#doc_chap1">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 <uri
104link="/dyn/use-index.xml#doc_chap2">online</uri> or locally in
110<path>/usr/portage/profiles/use.local.desc</path>. 105<path>/usr/portage/profiles/use.local.desc</path>.
111</p> 106</p>
112 107
113</body> 108</body>
114</subsection> 109</subsection>
115</section> 110</section>
116<section> 111<section>
117<title>Using USE-flags</title> 112<title>Using USE flags</title>
118<subsection> 113<subsection>
119<title>Declare permanent USE-flags</title> 114<title>Declare permanent USE flags</title>
120<body> 115<body>
121 116
122<p> 117<p>
123In the hope you are convinced of the importance of USE-flags we will now inform 118In the hope you are convinced of the importance of USE flags we will now inform
124you how to declare USE-flags. 119you how to declare USE flags.
125</p>
126
127<p> 120</p>
121
122<p>
128As previously mentioned, all USE-flags are declared inside the <c>USE</c> 123As 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 124variable. 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 125provide 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 126we think are commonly used by the Gentoo users. This default setting is declared
132in the <path>make.defaults</path> files part of your profile. 127in the <path>make.defaults</path> files part of your profile.
133</p> 128</p>
134 129
135<p> 130<p>
136The profile your system listens to is pointed to by the 131The profile your system listens to is pointed to by the
137<path>/etc/make.profile</path> symlink. Each profile works on top of another, 132<path>/etc/portage/make.profile</path> symlink. Each profile works on top of
138larger profile, the end result is therefore the sum of all profiles. The top 133another, larger profile, the end result is therefore the sum of all profiles.
139profile is the <path>base</path> profile 134The top profile is the <path>base</path> profile
140(<path>/usr/portage/profiles/base</path>). 135(<path>/usr/portage/profiles/base</path>).
141</p> 136</p>
142 137
143<p> 138<p>
144Let us take a look at this default setting for the 2004.3 profile: 139Let us take a look at this default setting for the 13.0 profile:
145</p> 140</p>
146 141
147<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile"> 142<pre caption="Cumulative make.defaults USE variable for the 13.0 profile">
148<comment>(This example is the sum of the settings in base, default-linux, 143<comment>(This example is the sum of the settings in base, default/linux,
149 default-linux/x86 and default-linux/x86/2004.3)</comment> 144 default/linux/x86 and default/linux/x86/13.0/)</comment>
150USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77 145USE="a52 aac acpi alsa branding cairo cdr dbus dts dvd dvdr emboss encode exif
151 foomaticdb gdbm gif gpm gtk gtk2 imlib jpeg kde gnome libg++ libwww mad 146fam firefox flac gif gpm gtk hal jpeg lcms ldap libnotify mad mikmod mng mp3
152 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt 147mp4 mpeg ogg opengl pango pdf png ppds qt3support qt4 sdl spell
153 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib" 148startup-notification svg tiff truetype vorbis unicode usb X xcb x264 xml xv
149xvid"
154</pre> 150</pre>
155 151
156<p> 152<p>
157As you can see, this variable already contains quite a lot of keywords. Do 153As you can see, this variable already contains quite a lot of keywords. Do
158<b>not</b> alter any <path>make.defaults</path> file to tailor 154<b>not</b> alter any <path>make.defaults</path> file to tailor
161</p> 157</p>
162 158
163<p> 159<p>
164To change this default setting, you need to add or remove keywords to the 160To 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 161<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 162in <path>/etc/portage/make.conf</path>. In this variable you add the extra USE
167require, or remove the USE-flags you don't want. This latter is done by 163flags you require, or remove the USE flags you don't want. This latter is done
168prefixing the keyword with the minus-sign ("-"). 164by prefixing the keyword with the minus-sign ("-").
169</p> 165</p>
170 166
171<p> 167<p>
172For instance, to remove support for KDE and QT but add support for ldap, the 168For 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>: 169following <c>USE</c> can be defined in <path>/etc/portage/make.conf</path>:
174</p> 170</p>
175 171
176<pre caption="An example USE setting in /etc/make.conf"> 172<pre caption="An example USE setting in /etc/portage/make.conf">
177USE="-kde -qt ldap" 173USE="-kde -qt4 ldap"
178</pre> 174</pre>
179 175
180</body> 176</body>
181</subsection> 177</subsection>
182<subsection> 178<subsection>
185 181
186<p> 182<p>
187Sometimes you want to declare a certain USE flag for one (or a couple) of 183Sometimes 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 184applications 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 185the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
190<path>/etc/portage/package.use</path>. 186<path>/etc/portage/package.use</path>. This is usually a single file, but can
187also be a directory; see <c>man portage</c> for more information. The following
188examples assume <path>package.use</path> is a single file.
191</p> 189</p>
192 190
193<p> 191<p>
194For instance, if you don't want <c>berkdb</c> support globally but you do want 192For instance, if you don't want <c>berkdb</c> support globally but you do want
195it for <c>mysql</c>, you would add: 193it for <c>mysql</c>, you would add:
209</pre> 207</pre>
210 208
211</body> 209</body>
212</subsection> 210</subsection>
213<subsection> 211<subsection>
214<title>Declare temporary USE-flags</title> 212<title>Declare temporary USE flags</title>
215<body> 213<body>
216 214
217<p> 215<p>
218Sometimes you want to set a certain USE-setting only once. Instead of editing 216Sometimes 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 217<path>/etc/portage/make.conf</path> twice (to do and undo the USE changes) you
220declare the USE-variable as environment variable. Remember that, when you 218can just declare the USE variable as environment variable. Remember that, when
221re-emerge or update this application (either explicitly or as part of a system 219you re-emerge or update this application (either explicitly or as part of a
222update) your changes will be lost! 220system update) your changes will be lost!
223</p>
224
225<p> 221</p>
222
223<p>
226As an example we will temporarily remove java from the USE-setting 224As an example we will temporarily remove java from the USE setting
227during the installation of mozilla. 225during the installation of seamonkey.
228</p> 226</p>
229 227
230<pre caption="Using USE as environment variable"> 228<pre caption="Using USE as environment variable">
231# <i>USE="-java" emerge mozilla</i> 229# <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> 230</pre>
255 231
256</body> 232</body>
257</subsection> 233</subsection>
258<subsection> 234<subsection>
271 <li> 247 <li>
272 Default USE setting declared in the <path>make.defaults</path> files part of 248 Default USE setting declared in the <path>make.defaults</path> files part of
273 your profile 249 your profile
274 </li> 250 </li>
275 <li> 251 <li>
276 Inherited USE setting if a package from profile <path>use.defaults</path> is installed
277 </li>
278 <li>
279 User-defined USE setting in <path>/etc/make.conf</path> 252 User-defined USE setting in <path>/etc/portage/make.conf</path>
280 </li> 253 </li>
281 <li> 254 <li>
282 User-defined USE setting in <path>/etc/portage/package.use</path> 255 User-defined USE setting in <path>/etc/portage/package.use</path>
283 </li> 256 </li>
284 <li> 257 <li>
345 318
346</body> 319</body>
347</subsection> 320</subsection>
348</section> 321</section>
349<section> 322<section>
350<title>Package specific USE-flags</title> 323<title>Package specific USE flags</title>
351<subsection> 324<subsection>
352<title>Viewing available USE-flags</title> 325<title>Viewing available USE flags</title>
353<body> 326<body>
354 327
355<p> 328<p>
356Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 329Let 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> 330find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
358options: 331options:
359</p> 332</p>
360 333
361<pre caption="Viewing the used USE-flags"> 334<pre caption="Viewing the used USE flags">
362# <i>emerge --pretend --verbose mozilla</i> 335# <i>emerge --pretend --verbose seamonkey</i>
363These are the packages that I would merge, in order: 336These are the packages that I would merge, in order:
364 337
365Calculating dependencies ...done! 338Calculating dependencies ...done!
366[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 339[ebuild R ] www-client/seamonkey-1.0.7 USE="crypt gnome java -debug -ipv6
367+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 340-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
368-moznocompose -moznoxft 341-moznoroaming -postgres -xinerama -xprint" 0 kB
369</pre> 342</pre>
370 343
371<p> 344<p>
372<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 345<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 346dedicated to package information called <c>equery</c> which resides in the
377<pre caption="Installing gentoolkit"> 350<pre caption="Installing gentoolkit">
378# <i>emerge gentoolkit</i> 351# <i>emerge gentoolkit</i>
379</pre> 352</pre>
380 353
381<p> 354<p>
382Now run <c>equery</c> with the <c>uses</c> argument to view the USE-flags of a 355Now 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: 356certain package. For instance, for the <c>gnumeric</c> package:
384</p> 357</p>
385 358
386<pre caption="Using equery to view used USE-flags"> 359<pre caption="Using equery to view used USE flags">
387# <i>equery uses gnumeric</i> 360# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
388[ Colour Code : <i>set</i> <comment>unset</comment> ] 361[ Searching for packages matching =gnumeric-1.6.3... ]
389[ Legend : (U) Col 1 - Current USE flags ] 362[ Colour Code : set unset ]
390[ : (I) Col 2 - Installed With USE flags ] 363[ Legend : Left column (U) - USE flags from make.conf ]
391 364[ : Right column (I) - USE flags packages was installed with ]
392 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 365[ Found these USE variables for app-office/gnumeric-1.6.3 ]
393 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 366 U I
394 - - <comment>gnomedb</comment> : unknown 367 - - debug : Enable extra debug codepaths, like asserts and extra output.
368 If you want to get meaningful backtraces see
369 http://www.gentoo.org/proj/en/qa/backtraces.xml .
370 + + gnome : Adds GNOME support
395 + + <i>python</i> : Adds support/bindings for the Python language 371 + + python : Adds support/bindings for the Python language
396 + + <i>bonobo</i> : Adds support for gnome-base/bonobo (Gnome CORBA interfaces) 372 - - static : !!do not set this during bootstrap!! Causes binaries to be
373 statically linked instead of dynamically
397</pre> 374</pre>
398 375
399</body> 376</body>
400</subsection> 377</subsection>
401</section> 378</section>

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