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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 1.20 2004/10/10 11:09:27 swift Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.55 2013/12/17 11:29:20 swift Exp $ -->
8 8
9<sections> 9<sections>
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
16<version>6</version>
17<date>2013-12-17</date>
18
10<section> 19<section>
11<title>What are USE-flags?</title> 20<title>What are USE flags?</title>
12<subsection> 21<subsection>
13<title>The ideas behind USE-flags</title> 22<title>The ideas behind USE flags</title>
14<body> 23<body>
15 24
16<p> 25<p>
17When you are installing Gentoo (or any other distribution, or even operating 26When you are installing Gentoo (or any other distribution, or even operating
18system 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
23<p> 32<p>
24This 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
25what 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
26would 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
27packages? 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
28with KDE-support if those packages work flawlessly without? 37with KDE support if those packages work flawlessly without?
29</p> 38</p>
30 39
31<p> 40<p>
32To 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
33user 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
34deciding 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
35managment system, to make useful decisions. 44management system, to make useful decisions.
36</p> 45</p>
37 46
38</body> 47</body>
39</subsection>
40<subsection> 48</subsection>
49<subsection>
41<title>Definition of a USE-flag</title> 50<title>Definition of a USE flag</title>
42<body> 51<body>
43 52
44<p> 53<p>
45Enter 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
46dependency-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,
47Portage 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
48this also alters the dependency information for a package. 57this also alters the dependency information for a package.
49</p> 58</p>
50 59
51<p> 60<p>
64</p> 73</p>
65 74
66</body> 75</body>
67</subsection> 76</subsection>
68<subsection> 77<subsection>
69<title>What USE-flags exist?</title> 78<title>What USE flags exist?</title>
70<body> 79<body>
71 80
72<p> 81<p>
73There 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.
74</p> 83</p>
75 84
76<ul> 85<ul>
77 <li> 86 <li>
78 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
79 what most people see as USE-flags. 88 what most people see as USE flags.
80 </li>
81 <li> 89 </li>
90 <li>
82 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
83 decisions. 92 decisions.
84 </li> 93 </li>
85</ul> 94</ul>
86 95
87<p> 96<p>
88A list of available global USE-flags can be found <uri 97A list of available global USE flags can be found <uri
89link="/dyn/use-index.xml">online</uri> or locally in 98link="/dyn/use-index.xml#doc_chap1">online</uri> or locally in
90<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 99<path>/usr/portage/profiles/use.desc</path>.
91snippet:
92</p>
93
94<pre caption="A short snippet of available USE-flags">
95gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
96gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
97gtkhtml - Adds support for gnome-extra/gtkhtml
98guile - Adds support for dev-util/guile (interpreter for Scheme)
99icc - Use the Intel C++ Compiler if the package supports it
100icc-pgo - Enable PGO data generation or use when use icc.
101imap - Adds support for IMAP
102</pre>
103
104<p> 100</p>
101
102<p>
105A 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
106<path>/usr/portage/profiles/use.local.desc</path>. 105<path>/usr/portage/profiles/use.local.desc</path>.
107</p> 106</p>
108 107
109</body> 108</body>
110</subsection> 109</subsection>
111</section> 110</section>
112<section> 111<section>
113<title>Using USE-flags</title> 112<title>Using USE flags</title>
114<subsection> 113<subsection>
115<title>Declare permanent USE-flags</title> 114<title>Declare permanent USE flags</title>
116<body> 115<body>
117 116
118<p> 117<p>
119In 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
120you how to declare USE-flags. 119you how to declare USE flags.
121</p>
122
123<p> 120</p>
121
122<p>
124As 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>
125variable. 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
126provide 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
127we 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
128in the <path>/etc/make.profile/make.defaults</path> file. Let us take a look at 127in the <path>make.defaults</path> files part of your profile.
129this default setting: 128</p>
129
130</p> 130<p>
131The profile your system listens to is pointed to by the
132<path>/etc/portage/make.profile</path> symlink. Each profile works on top of
133another, larger profile, the end result is therefore the sum of all profiles.
134The top profile is the <path>base</path> profile
135(<path>/usr/portage/profiles/base</path>).
136</p>
131 137
132<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 138<p>
133USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 139Let us take a look at this default setting for the 13.0 profile:
134 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 140</p>
135 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 141
136 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 142<pre caption="Cumulative make.defaults USE variable for the 13.0 profile">
143<comment>(This example is the sum of the settings in base, default/linux,
144 default/linux/x86 and default/linux/x86/13.0/)</comment>
145USE="a52 aac acpi alsa branding cairo cdr dbus dts dvd dvdr emboss encode exif
146fam firefox flac gif gpm gtk hal jpeg lcms ldap libnotify mad mikmod mng mp3
147mp4 mpeg ogg opengl pango pdf png ppds qt3support qt4 sdl spell
148startup-notification svg tiff truetype vorbis unicode usb X xcb x264 xml xv
149xvid"
137</pre> 150</pre>
138 151
139<p> 152<p>
140As 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
141<b>not</b> alter the <path>/etc/make.profile/make.defaults</path> file to tailor 154<b>not</b> alter any <path>make.defaults</path> file to tailor
142the <c>USE</c> variable to your needs: changes in this file will be undone when 155the <c>USE</c> variable to your needs: changes in this file will be undone when
143you update Portage! 156you update Portage!
144</p> 157</p>
145 158
146<p> 159<p>
147To 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
148<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
149in <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
150require, 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
151prefixing the keyword with the minus-sign ("-"). 164by prefixing the keyword with the minus-sign ("-").
152</p> 165</p>
153 166
154<p> 167<p>
155For 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
156following <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>:
157</p> 170</p>
158 171
159<pre caption="An example USE setting in /etc/make.conf"> 172<pre caption="An example USE setting in /etc/portage/make.conf">
160USE="-kde -qt ldap" 173USE="-kde -qt4 ldap"
161</pre> 174</pre>
162 175
163</body> 176</body>
164</subsection> 177</subsection>
165<subsection> 178<subsection>
168 181
169<p> 182<p>
170Sometimes 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
171applications 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
172the <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
173<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.
174</p> 189</p>
175 190
176<p> 191<p>
177For 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
178it for <c>mysql</c>, you would add: 193it for <c>mysql</c>, you would add:
192</pre> 207</pre>
193 208
194</body> 209</body>
195</subsection> 210</subsection>
196<subsection> 211<subsection>
197<title>Declare temporary USE-flags</title> 212<title>Declare temporary USE flags</title>
198<body> 213<body>
199 214
200<p> 215<p>
201Sometimes 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
202<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
203declare the USE-variable as environment variable. Remember that, when you 218can just declare the USE variable as environment variable. Remember that, when
204re-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
205update) your changes will be lost! 220system update) your changes will be lost!
206</p>
207
208<p> 221</p>
222
223<p>
209As an example we will temporarily remove java from the USE-setting 224As an example we will temporarily remove java from the USE setting
210during the installation of mozilla. 225during the installation of seamonkey.
211</p> 226</p>
212
213<note>
214The <c>emerge</c> command will be discussed more thoroughly in <uri
215link="?part=2&amp;chap=2">Portage and Software</uri>.
216</note>
217 227
218<pre caption="Using USE as environment variable"> 228<pre caption="Using USE as environment variable">
219# <i>USE="-java" emerge mozilla</i> 229# <i>USE="-java" emerge seamonkey</i>
220</pre>
221
222</body>
223</subsection>
224<subsection>
225<title>Inheriting USE-flags</title>
226<body>
227
228<p>
229Some packages don't only listen to USE-flags, but also provide USE-flags. When
230you install such a package, the USE-flag they provide is added to your USE
231setting. To view the list of packages that provide a USE-flag, check
232<path>/etc/make.profile/use.defaults</path>:
233</p>
234
235<pre caption="A snippet from /etc/make.profile/use.defaults">
236gnome gnome-base/gnome
237gtk x11-libs/gtk+
238qt x11-libs/qt
239kde kde-base/kdebase
240motif x11-libs/openmotif
241</pre> 230</pre>
242 231
243</body> 232</body>
244</subsection> 233</subsection>
245<subsection> 234<subsection>
246<title>Precedence</title> 235<title>Precedence</title>
247<body> 236<body>
248 237
249<p> 238<p>
250Of course there is a certain precedence on what setting has priority over the 239Of course there is a certain precedence on what setting has priority over the
251USE setting. You don't want to declare <c>USE="-java"</c> only to see that 240USE setting. You don't want to declare <c>USE="-java"</c> only to see that
252<c>java</c> is declared anyway. The precedence for the USE setting is, ordered 241<c>java</c> is still used due to a setting that has a higher priority.
242The precedence for the USE setting is, ordered
253by priority (first has lowest priority): 243by priority (first has lowest priority):
254</p> 244</p>
255 245
256<ol> 246<ol>
257 <li> 247 <li>
258 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 248 Default USE setting declared in the <path>make.defaults</path> files part of
259 </li> 249 your profile
260 <li> 250 </li>
261 Inherited USE setting if a package from
262 <path>/etc/make.profile/use.defaults</path> is installed
263 </li> 251 <li>
264 <li>
265 User-defined USE setting in <path>/etc/make.conf</path> 252 User-defined USE setting in <path>/etc/portage/make.conf</path>
266 </li> 253 </li>
267 <li> 254 <li>
268 User-defined USE setting in <path>/etc/portage/package.use</path> 255 User-defined USE setting in <path>/etc/portage/package.use</path>
269 </li> 256 </li>
270 <li> 257 <li>
271 User-defined USE setting as environment variable 258 User-defined USE setting as environment variable
272 </li> 259 </li>
273</ol> 260</ol>
274 261
275<p> 262<p>
276To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 263To view the final <c>USE</c> setting as seen by Portage, run <c>emerge
277This will list all relevant variables (including the <c>USE</c> variable) with 264--info</c>. This will list all relevant variables (including the <c>USE</c>
278the content used by Portage. 265variable) with the content used by Portage.
279</p> 266</p>
280 267
281<pre caption="Running emerge info"> 268<pre caption="Running emerge --info">
282# <i>emerge info</i> 269# <i>emerge --info</i>
283</pre> 270</pre>
284 271
285</body> 272</body>
286</subsection> 273</subsection>
287<subsection> 274<subsection>
288<title>Adapting your Entire System to New USE Flags</title> 275<title>Adapting your Entire System to New USE Flags</title>
289<body> 276<body>
290 277
291<p> 278<p>
292If you have altered your USE flags and you wish to update your entire system to 279If you have altered your USE flags and you wish to update your entire system to
293use the new USE flags, you can try following the next steps to accomplish this. 280use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
294Note however that these steps will take a long time to finish and that work is
295on the way to adjust Portage to handle this behaviour quicker and automatically.
296</p>
297
298<p>
299First of all, rebuild your entire system using the new USE flags:
300</p> 281</p>
301 282
302<pre caption="Rebuilding your entire system"> 283<pre caption="Rebuilding your entire system">
303# <i>emerge --emptytree world</i> 284# <i>emerge --update --deep --newuse @world</i>
304</pre> 285</pre>
305 286
306<p> 287<p>
307Next, run Portage's depclean to remove the conditional dependencies that 288Next, run Portage's depclean to remove the conditional dependencies that
308were emerged on your "old" system but that have been obsoleted by the new USE 289were emerged on your "old" system but that have been obsoleted by the new USE
309flags. 290flags.
310</p> 291</p>
311 292
312<warn> 293<warn>
313Running <c>emerge depclean</c> is a dangerous operation and should be handled 294Running <c>emerge --depclean</c> is a dangerous operation and should be handled
314with care. Double-check the provided list of "obsoleted" packages to make sure 295with care. Double-check the provided list of "obsoleted" packages to make sure
315it doesn't remove packages you need. In the following example we add the 296it doesn't remove packages you need. In the following example we add the
316<c>-p</c> switch to have depclean only list the packages without removing them. 297<c>-p</c> switch to have depclean only list the packages without removing them.
317</warn> 298</warn>
318 299
319<pre caption="Removing obsoleted packages"> 300<pre caption="Removing obsoleted packages">
320# <i>emerge -p depclean</i> 301# <i>emerge -p --depclean</i>
321</pre> 302</pre>
322 303
304<p>
305When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
306applications that are dynamically linked against shared objects provided by
307possibly removed packages. <c>revdep-rebuild</c> is part of the
308<c>gentoolkit</c> package; don't forget to emerge it first.
323<p> 309</p>
310
311<pre caption="Running revdep-rebuild">
312# <i>revdep-rebuild</i>
313</pre>
314
315<p>
324When depclean has finished, your system is using the new USE flag settings. 316When all this is accomplished, your system is using the new USE flag settings.
325</p> 317</p>
326 318
327</body> 319</body>
328</subsection> 320</subsection>
329</section> 321</section>
330<section> 322<section>
331<title>Package specific USE-flags</title> 323<title>Package specific USE flags</title>
332<subsection> 324<subsection>
333<title>Viewing available USE-flags</title> 325<title>Viewing available USE flags</title>
334<body> 326<body>
335 327
336<p>
337In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
338we will explain how to manage your installed software and how to work with
339<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
340you how to view what USE-flags a package uses.
341</p> 328<p>
342
343<p>
344Let 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
345find out, we use <c>emerge</c> with the <c>--pretend</c> (don't really do 330find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
346anything) and <c>--verbose</c> (give more output) options: 331options:
347</p> 332</p>
348 333
349<pre caption="Viewing the used USE-flags"> 334<pre caption="Viewing the used USE flags">
350# <i>emerge --pretend --verbose mozilla</i> 335# <i>emerge --pretend --verbose seamonkey</i>
351These are the packages that I would merge, in order: 336These are the packages that I would merge, in order:
352 337
353Calculating dependencies ...done! 338Calculating dependencies ...done!
354[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
355+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 340-ldap -mozcalendar -mozdevelop -moznocompose -moznoirc -moznomail -moznopango
356-moznocompose -moznoxft 341-moznoroaming -postgres -xinerama -xprint" 0 kB
357</pre> 342</pre>
358 343
359<p> 344<p>
360<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
361dedicated to package information called <c>etcat</c> which resides in the 346dedicated to package information called <c>equery</c> which resides in the
362<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 347<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
363</p> 348</p>
364 349
365<pre caption="Installing gentoolkit"> 350<pre caption="Installing gentoolkit">
366# <i>emerge --usepkg gentoolkit</i> 351# <i>emerge gentoolkit</i>
367</pre> 352</pre>
368 353
369<p> 354<p>
370Now run <c>etcat</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
371certain package. For instance, for the <c>gnumeric</c> package: 356certain package. For instance, for the <c>gnumeric</c> package:
372</p> 357</p>
373 358
374<pre caption="Using etcat to view used USE-flags"> 359<pre caption="Using equery to view used USE flags">
375# <i>etcat uses gnumeric</i> 360# <i>equery --nocolor uses =gnumeric-1.6.3 -a</i>
376[ Colour Code : <i>set</i> <comment>unset</comment> ] 361[ Searching for packages matching =gnumeric-1.6.3... ]
377[ Legend : (U) Col 1 - Current USE flags ] 362[ Colour Code : set unset ]
378[ : (I) Col 2 - Installed With USE flags ] 363[ Legend : Left column (U) - USE flags from make.conf ]
379 364[ : Right column (I) - USE flags packages was installed with ]
380 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 ]
381 - - <comment>libgda</comment> : Adds GNU Data Access (CORBA wrapper) support for gnumeric 366 U I
382 - - <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
383 + + <i>python</i> : Adds support/bindings for the Python language 371 + + python : Adds support/bindings for the Python language
384 + + <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
385</pre> 374</pre>
386 375
387</body> 376</body>
388</subsection> 377</subsection>
389</section> 378</section>

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