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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 1.24 2004/11/20 22:23:30 neysx Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.50 2010/06/07 09:20:00 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>1.21</version> 16<version>1.39</version>
12<date>2004-10-21</date> 17<date>2010-06-07</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>/etc/make.profile/make.defaults</path> file. Let us take a look at 126in the <path>make.defaults</path> files part of your profile.
133this default setting: 127</p>
128
134</p> 129<p>
130The profile your system listens to is pointed to by the
131<path>/etc/make.profile</path> symlink. Each profile works on top of another,
132larger profile, the end result is therefore the sum of all profiles. The top
133profile is the <path>base</path> profile
134(<path>/usr/portage/profiles/base</path>).
135</p>
135 136
136<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 137<p>
137USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 138Let us take a look at this default setting for the 10.0 profile:
138 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 139</p>
139 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 140
140 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 141<pre caption="Cumulative make.defaults USE variable for the 10.0 profile">
142<comment>(This example is the sum of the settings in base, default/linux,
143 default/linux/x86 and default/linux/x86/10.0/)</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
148xulrunner xv xvid"
141</pre> 149</pre>
142 150
143<p> 151<p>
144As 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
145<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
146the <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
147you update Portage! 155you update Portage!
148</p> 156</p>
149 157
150<p> 158<p>
151To 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
152<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
153in <path>/etc/make.conf</path>. In this variable you add the extra USE-flags you 161in <path>/etc/make.conf</path>. In this variable you add the extra USE flags you
154require, or remove the USE-flags you don't want. This latter is done by 162require, or remove the USE flags you don't want. This latter is done by
155prefixing the keyword with the minus-sign ("-"). 163prefixing the keyword with the minus-sign ("-").
156</p> 164</p>
157 165
158<p> 166<p>
159For 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
160following <c>USE</c> can be defined in <path>/etc/make.conf</path>: 168following <c>USE</c> can be defined in <path>/etc/make.conf</path>:
161</p> 169</p>
162 170
163<pre caption="An example USE setting in /etc/make.conf"> 171<pre caption="An example USE setting in /etc/make.conf">
164USE="-kde -qt ldap" 172USE="-kde -qt4 ldap"
165</pre> 173</pre>
166 174
167</body> 175</body>
168</subsection> 176</subsection>
169<subsection> 177<subsection>
172 180
173<p> 181<p>
174Sometimes you want to declare a certain USE flag for one (or a couple) of 182Sometimes you want to declare a certain USE flag for one (or a couple) of
175applications but not system-wide. To accomplish this, you will need to create 183applications but not system-wide. To accomplish this, you will need to create
176the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit 184the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
177<path>/etc/portage/package.use</path>. 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.
178</p> 188</p>
179 189
180<p> 190<p>
181For instance, if you don't want <c>berkdb</c> support globally but you do want 191For instance, if you don't want <c>berkdb</c> support globally but you do want
182it for <c>mysql</c>, you would add: 192it for <c>mysql</c>, you would add:
196</pre> 206</pre>
197 207
198</body> 208</body>
199</subsection> 209</subsection>
200<subsection> 210<subsection>
201<title>Declare temporary USE-flags</title> 211<title>Declare temporary USE flags</title>
202<body> 212<body>
203 213
204<p> 214<p>
205Sometimes 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
206<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 216<path>/etc/make.conf</path> twice (to do and undo the USE changes) you can just
207declare the USE-variable as environment variable. Remember that, when you 217declare the USE variable as environment variable. Remember that, when you
208re-emerge or update this application (either explicitly or as part of a system 218re-emerge or update this application (either explicitly or as part of a system
209update) your changes will be lost! 219update) your changes will be lost!
210</p> 220</p>
211 221
212<p> 222<p>
213As an example we will temporarily remove java from the USE-setting 223As an example we will temporarily remove java from the USE setting
214during the installation of mozilla. 224during the installation of seamonkey.
215</p> 225</p>
216 226
217<pre caption="Using USE as environment variable"> 227<pre caption="Using USE as environment variable">
218# <i>USE="-java" emerge mozilla</i> 228# <i>USE="-java" emerge seamonkey</i>
219</pre>
220
221</body>
222</subsection>
223<subsection>
224<title>Inheriting USE-flags</title>
225<body>
226
227<p>
228Some packages don't only listen to USE-flags, but also provide USE-flags. When
229you install such a package, the USE-flag they provide is added to your USE
230setting. To view the list of packages that provide a USE-flag, check
231<path>/etc/make.profile/use.defaults</path>:
232</p>
233
234<pre caption="A snippet from /etc/make.profile/use.defaults">
235gnome gnome-base/gnome
236gtk x11-libs/gtk+
237qt x11-libs/qt
238kde kde-base/kdebase
239motif x11-libs/openmotif
240</pre> 229</pre>
241 230
242</body> 231</body>
243</subsection> 232</subsection>
244<subsection> 233<subsection>
245<title>Precedence</title> 234<title>Precedence</title>
246<body> 235<body>
247 236
248<p> 237<p>
249Of 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
250USE 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
251<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
252by priority (first has lowest priority): 242by priority (first has lowest priority):
253</p> 243</p>
254 244
255<ol> 245<ol>
256 <li> 246 <li>
257 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
258 </li> 248 your profile
259 <li>
260 Inherited USE setting if a package from
261 <path>/etc/make.profile/use.defaults</path> is installed
262 </li> 249 </li>
263 <li> 250 <li>
264 User-defined USE setting in <path>/etc/make.conf</path> 251 User-defined USE setting in <path>/etc/make.conf</path>
265 </li> 252 </li>
266 <li> 253 <li>
270 User-defined USE setting as environment variable 257 User-defined USE setting as environment variable
271 </li> 258 </li>
272</ol> 259</ol>
273 260
274<p> 261<p>
275To 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
276This 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>
277the content used by Portage. 264variable) with the content used by Portage.
278</p> 265</p>
279 266
280<pre caption="Running emerge info"> 267<pre caption="Running emerge --info">
281# <i>emerge info</i> 268# <i>emerge --info</i>
282</pre> 269</pre>
283 270
284</body> 271</body>
285</subsection> 272</subsection>
286<subsection> 273<subsection>
301were 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
302flags. 289flags.
303</p> 290</p>
304 291
305<warn> 292<warn>
306Running <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
307with 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
308it 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
309<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.
310</warn> 297</warn>
311 298
312<pre caption="Removing obsoleted packages"> 299<pre caption="Removing obsoleted packages">
313# <i>emerge -p depclean</i> 300# <i>emerge -p --depclean</i>
314</pre> 301</pre>
315 302
316<p> 303<p>
317When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 304When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
318applications that are dynamically linked against shared objects provided by 305applications that are dynamically linked against shared objects provided by
330 317
331</body> 318</body>
332</subsection> 319</subsection>
333</section> 320</section>
334<section> 321<section>
335<title>Package specific USE-flags</title> 322<title>Package specific USE flags</title>
336<subsection> 323<subsection>
337<title>Viewing available USE-flags</title> 324<title>Viewing available USE flags</title>
338<body> 325<body>
339 326
340<p> 327<p>
341Let 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
342find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c> 329find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
343options: 330options:
344</p> 331</p>
345 332
346<pre caption="Viewing the used USE-flags"> 333<pre caption="Viewing the used USE flags">
347# <i>emerge --pretend --verbose mozilla</i> 334# <i>emerge --pretend --verbose seamonkey</i>
348These are the packages that I would merge, in order: 335These are the packages that I would merge, in order:
349 336
350Calculating dependencies ...done! 337Calculating dependencies ...done!
351[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
352+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 339-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
353-moznocompose -moznoxft 340-moznoroaming -postgres -xinerama -xprint" 0 kB
354</pre> 341</pre>
355 342
356<p> 343<p>
357<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
358dedicated to package information called <c>etcat</c> which resides in the 345dedicated to package information called <c>equery</c> which resides in the
359<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 346<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
360</p> 347</p>
361 348
362<pre caption="Installing gentoolkit"> 349<pre caption="Installing gentoolkit">
363# <i>emerge gentoolkit</i> 350# <i>emerge gentoolkit</i>
364</pre> 351</pre>
365 352
366<p> 353<p>
367Now 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
368certain package. For instance, for the <c>gnumeric</c> package: 355certain package. For instance, for the <c>gnumeric</c> package:
369</p> 356</p>
370 357
371<pre caption="Using etcat to view used USE-flags"> 358<pre caption="Using equery to view used USE flags">
372# <i>etcat uses gnumeric</i> 359# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
373[ Colour Code : <i>set</i> <comment>unset</comment> ] 360[ Searching for packages matching =gnumeric-1.6.3... ]
374[ Legend : (U) Col 1 - Current USE flags ] 361[ Colour Code : set unset ]
375[ : (I) Col 2 - Installed With USE flags ] 362[ Legend : Left column (U) - USE flags from make.conf ]
376 363[ : Right column (I) - USE flags packages was installed with ]
377 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 ]
378 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 365 U I
379 - - <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
380 + + <i>python</i> : Adds support/bindings for the Python language 370 + + python : Adds support/bindings for the Python language
381 + + <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
382</pre> 373</pre>
383 374
384</body> 375</body>
385</subsection> 376</subsection>
386</section> 377</section>

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