/[gentoo]/xml/htdocs/doc/en/handbook/hb-working-use.xml
Gentoo

Diff of /xml/htdocs/doc/en/handbook/hb-working-use.xml

Parent Directory Parent Directory | Revision Log Revision Log | View Patch Patch

Revision 1.5 Revision 1.28
1<?xml version='1.0' encoding='UTF-8'?>
2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
3
1<!-- 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 -->
2<!-- See http://creativecommons.org/licenses/by-sa/1.0 --> 5<!-- See http://creativecommons.org/licenses/by-sa/1.0 -->
3 6
4<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.5 2003/12/16 18:08:56 swift Exp $ --> 7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.28 2005/01/23 08:47:30 swift Exp $ -->
5 8
6<sections> 9<sections>
10
11<version>1.25</version>
12<date>2005-01-23</date>
13
7<section> 14<section>
8<title>What are USE-flags?</title> 15<title>What are USE-flags?</title>
9<subsection> 16<subsection>
10<title>The ideas behind USE-flags</title> 17<title>The ideas behind USE-flags</title>
11<body> 18<body>
25with KDE-support if those packages work flawlessly without? 32with KDE-support if those packages work flawlessly without?
26</p> 33</p>
27 34
28<p> 35<p>
29To help users in deciding what to install/activate and what not, we wanted the 36To help users in deciding what to install/activate and what not, we wanted the
30user to specify his environment in an easy way. This forces the user into 37user to specify his/her environment in an easy way. This forces the user into
31deciding what he really wants and eases the process for Portage, our package 38deciding what they really want and eases the process for Portage, our package
32managment system, to make useful decisions. 39managment system, to make useful decisions.
33</p> 40</p>
34 41
35</body> 42</body>
36</subsection> 43</subsection>
44Portage will know that you want support for the chosen keyword. Of course 51Portage will know that you want support for the chosen keyword. Of course
45this also alters the dependency information for a package. 52this also alters the dependency information for a package.
46</p> 53</p>
47 54
48<p> 55<p>
49Lets take a look at a specific example: the <c>kde</c> keyword. If you do not 56Let us take a look at a specific example: the <c>kde</c> keyword. If you do not
50have this keyword in your <c>USE</c> variable, all packages that have 57have this keyword in your <c>USE</c> variable, all packages that have
51<e>optional</e> KDE support will be compiled <e>without</e> KDE support. All 58<e>optional</e> KDE support will be compiled <e>without</e> KDE support. All
52packages that have an <e>optional</e> KDE dependency will be installed 59packages that have an <e>optional</e> KDE dependency will be installed
53<e>without</e> installing the KDE libraries (as dependency). If you have defined 60<e>without</e> installing the KDE libraries (as dependency). If you have defined
54the <c>kde</c> keyword, then those packages <e>will</e> be compiled with KDE 61the <c>kde</c> keyword, then those packages <e>will</e> be compiled with KDE
74 <li> 81 <li>
75 A <e>global</e> USE-flag is used by several packages, system-wide. This is 82 A <e>global</e> USE-flag is used by several packages, system-wide. This is
76 what most people see as USE-flags. 83 what most people see as USE-flags.
77 </li> 84 </li>
78 <li> 85 <li>
79 A <e>local</e> USE-fag is used by a single package to make package-specific 86 A <e>local</e> USE-flag is used by a single package to make package-specific
80 decisions. 87 decisions.
81 </li> 88 </li>
82</ul> 89</ul>
83 90
84<p> 91<p>
96icc - Use the Intel C++ Compiler if the package supports it 103icc - Use the Intel C++ Compiler if the package supports it
97icc-pgo - Enable PGO data generation or use when use icc. 104icc-pgo - Enable PGO data generation or use when use icc.
98imap - Adds support for IMAP 105imap - Adds support for IMAP
99</pre> 106</pre>
100 107
108<p>
109A list of available local USE-flags can be found locally in
110<path>/usr/portage/profiles/use.local.desc</path>.
111</p>
112
101</body> 113</body>
102</subsection> 114</subsection>
103</section> 115</section>
104<section> 116<section>
105<title>Using USE-flags</title> 117<title>Using USE-flags</title>
115<p> 127<p>
116As previously mentioned, all USE-flags are declared inside the <c>USE</c> 128As previously mentioned, all USE-flags are declared inside the <c>USE</c>
117variable. To make it easy for users to search and pick USE-flags, we already 129variable. To make it easy for users to search and pick USE-flags, we already
118provide a <e>default</e> USE setting. This setting is a collection of USE-flags 130provide a <e>default</e> USE setting. This setting is a collection of USE-flags
119we think are commonly used by the Gentoo users. This default setting is declared 131we think are commonly used by the Gentoo users. This default setting is declared
120in the <path>/etc/make.profile/make.defaults</path> file. Let us take a look at 132in the <path>make.defaults</path> files part of your profile.
121this default setting: 133</p>
134
122</p> 135<p>
136The profile your system listens to is pointed to by the
137<path>/etc/make.profile</path> symlink. Each profile works on top of another,
138larger profile, the end result is therefore the sum of all profiles. The top
139profile is the <path>base</path> profile
140(<path>/usr/portage/profiles/base</path>).
141</p>
123 142
124<pre caption="/etc/make.profile/make.defaults USE variable"> 143<p>
125USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm gtk 144Let us take a look at this default setting:
126 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses nls 145</p>
127 oggvorbis opengl pam pdflib png python qt quicktime readline sdl slang 146
147<pre caption="Cumulated /usr/portage/profiles/default-linux/x86/2004.3/make.defaults USE variable">
148<comment>(This example is the sum of the settings in base, default-linux,
149 default-linux/x86 and default-linux/x86/2004.3)</comment>
150USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77
151 foomaticdb gdbm gif gpm gtk gtk2 imlib jpeg kde gnome libg++ libwww mad
152 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt
128 spell ssl svga tcpd truetype X xml2 xmms xv zlib" 153 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
129</pre> 154</pre>
130 155
131<p> 156<p>
132As you can see, this variable already contains quite a lot of keywords. Do 157As you can see, this variable already contains quite a lot of keywords. Do
133<b>not</b> alter the <path>/etc/make.profile/make.defaults</path> file to tailor 158<b>not</b> alter any <path>make.defaults</path> file to tailor
134the <c>USE</c> variable to your needs: changes in this file will be undone when 159the <c>USE</c> variable to your needs: changes in this file will be undone when
135you update Portage! 160you update Portage!
136</p> 161</p>
137 162
138<p> 163<p>
153</pre> 178</pre>
154 179
155</body> 180</body>
156</subsection> 181</subsection>
157<subsection> 182<subsection>
183<title>Declaring USE flags for individual packages</title>
184<body>
185
186<p>
187Sometimes 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
189the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
190<path>/etc/portage/package.use</path>.
191</p>
192
193<p>
194For instance, if you don't want <c>berkdb</c> support globally but you do want
195it for <c>mysql</c>, you would add:
196</p>
197
198<pre caption="/etc/portage/package.use example">
199dev-db/mysql berkdb
200</pre>
201
202<p>
203You can of course also explicitly <e>disable</e> USE flags for a certain
204application. For instance, if you don't want <c>java</c> support in PHP:
205</p>
206
207<pre caption="/etc/portage/package.use 2nd example">
208dev-php/php -java
209</pre>
210
211</body>
212</subsection>
213<subsection>
158<title>Declare temporary USE-flags</title> 214<title>Declare temporary USE-flags</title>
159<body> 215<body>
160 216
161<p> 217<p>
162Sometimes you want to set a certain USE-setting only once. Instead of editing 218Sometimes you want to set a certain USE-setting only once. Instead of editing
163<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just 219<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just
164declare the USE-variable as environment variable. 220declare the USE-variable as environment variable. Remember that, when you
221re-emerge or update this application (either explicitly or as part of a system
222update) your changes will be lost!
165</p> 223</p>
166 224
167<p> 225<p>
168As an example we will temporarily remove java from the USE-setting 226As an example we will temporarily remove java from the USE-setting
169during the installation of mozilla. 227during the installation of mozilla.
170</p> 228</p>
171 229
172<note>
173The <c>emerge</c> command will be discussed more thoroughly in <uri
174link="?part=2&amp;chap=2">Portage and Software</uri>.
175</note>
176
177<pre caption="Using USE as evironment variable"> 230<pre caption="Using USE as environment variable">
178# <i>USE="-java" emerge mozilla</i> 231# <i>USE="-java" emerge mozilla</i>
179</pre> 232</pre>
180 233
181</body> 234</body>
182</subsection> 235</subsection>
200</pre> 253</pre>
201 254
202</body> 255</body>
203</subsection> 256</subsection>
204<subsection> 257<subsection>
205<title>Precendence</title> 258<title>Precedence</title>
206<body> 259<body>
207 260
208<p> 261<p>
209Of course there is a certain precendence on what setting has priority over the 262Of course there is a certain precedence on what setting has priority over the
210USE setting. You don't want to declare <c>USE="-java"</c> only to see that 263USE setting. You don't want to declare <c>USE="-java"</c> only to see that
211<c>java</c> is declared anyway. The precedence for the USE setting is, ordered 264<c>java</c> is declared anyway. The precedence for the USE setting is, ordered
212by priority (first has lowest priority): 265by priority (first has lowest priority):
213</p> 266</p>
214 267
215<ol> 268<ol>
216 <li> 269 <li>
217 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 270 Default USE setting declared in the <path>make.defaults</path> files part of
271 your profile
218 </li> 272 </li>
219 <li> 273 <li>
220 Inherited USE setting if a package from 274 Inherited USE setting if a package from
221 <path>/etc/make.profile/use.defaults</path> is installed 275 <path>/etc/make.profile/use.defaults</path> is installed
222 </li> 276 </li>
223 <li> 277 <li>
224 User-defined USE setting in <path>/etc/make.conf</path> 278 User-defined USE setting in <path>/etc/make.conf</path>
225 </li> 279 </li>
226 <li> 280 <li>
281 User-defined USE setting in <path>/etc/portage/package.use</path>
282 </li>
283 <li>
227 User-defined USE setting as environment variable 284 User-defined USE setting as environment variable
228 </li> 285 </li>
229</ol> 286</ol>
230 287
231<p> 288<p>
232To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 289To view the final <c>USE</c> setting as seen by Portage, run <c>emerge
233This will list all relevant variables (including the <c>USE</c> variable) with 290--info</c>. This will list all relevant variables (including the <c>USE</c>
234the content used by Portage. 291variable) with the content used by Portage.
235</p> 292</p>
236 293
237<pre caption="Running emerge info"> 294<pre caption="Running emerge --info">
238# <i>emerge info</i> 295# <i>emerge --info</i>
296</pre>
297
298</body>
299</subsection>
300<subsection>
301<title>Adapting your Entire System to New USE Flags</title>
302<body>
303
304<p>
305If you have altered your USE flags and you wish to update your entire system to
306use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
239</pre> 307</p>
308
309<pre caption="Rebuilding your entire system">
310# <i>emerge --update --deep --newuse world</i>
311</pre>
312
313<p>
314Next, run Portage's depclean to remove the conditional dependencies that
315were emerged on your "old" system but that have been obsoleted by the new USE
316flags.
317</p>
318
319<warn>
320Running <c>emerge --depclean</c> is a dangerous operation and should be handled
321with care. Double-check the provided list of "obsoleted" packages to make sure
322it doesn't remove packages you need. In the following example we add the
323<c>-p</c> switch to have depclean only list the packages without removing them.
324</warn>
325
326<pre caption="Removing obsoleted packages">
327# <i>emerge -p --depclean</i>
328</pre>
329
330<p>
331When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
332applications that are dynamically linked against shared objects provided by
333possibly removed packages. <c>revdep-rebuild</c> is part of the
334<c>gentoolkit</c> package; don't forget to emerge it first.
335</p>
336
337<pre caption="Running revdep-rebuild">
338# <i>revdep-rebuild</i>
339</pre>
340
341<p>
342When all this is accomplished, your system is using the new USE flag settings.
343</p>
240 344
241</body> 345</body>
242</subsection> 346</subsection>
243</section> 347</section>
244<section> 348<section>
246<subsection> 350<subsection>
247<title>Viewing available USE-flags</title> 351<title>Viewing available USE-flags</title>
248<body> 352<body>
249 353
250<p> 354<p>
251In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
252we will explain how to manage your installed software and how to work with
253<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
254you how to view what USE-flags a package uses.
255</p>
256
257<p>
258Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 355Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To
259find out, we use <c>emerge</c> with the <c>--pretend</c> (don't really do 356find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
260anything) and <c>--verbose</c> (give more output) options: 357options:
261</p> 358</p>
262 359
263<pre caption="Viewing the used USE-flags"> 360<pre caption="Viewing the used USE-flags">
264# <i>emerge --pretend --verbose mozilla</i> 361# <i>emerge --pretend --verbose mozilla</i>
265These are the packages that I would merge, in order: 362These are the packages that I would merge, in order:
275dedicated to package information called <c>etcat</c> which resides in the 372dedicated to package information called <c>etcat</c> which resides in the
276<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 373<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
277</p> 374</p>
278 375
279<pre caption="Installing gentoolkit"> 376<pre caption="Installing gentoolkit">
280# <i>emerge --usepkg gentoolkit</i> 377# <i>emerge gentoolkit</i>
281</pre> 378</pre>
282 379
283<p> 380<p>
284Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 381Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a
285certain package. For instance, for the <c>gnumeric</c> package: 382certain package. For instance, for the <c>gnumeric</c> package:

Legend:
Removed from v.1.5  
changed lines
  Added in v.1.28

  ViewVC Help
Powered by ViewVC 1.1.20