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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 1.36 2005/10/26 14:37:18 rane Exp $ -->
8 8
9<sections> 9<sections>
10 10
11<version>1.21</version> 11<version>1.31</version>
12<date>2004-10-21</date> 12<date>2005-10-26</date>
13 13
14<section> 14<section>
15<title>What are USE-flags?</title> 15<title>What are USE-flags?</title>
16<subsection> 16<subsection>
17<title>The ideas behind USE-flags</title> 17<title>The ideas behind USE-flags</title>
127<p> 127<p>
128As 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>
129variable. 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
130provide 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
131we 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
132in 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.
133this default setting: 133</p>
134
134</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>
135 142
136<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 143<p>
137USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 144Let us take a look at this default setting for the 2004.3 profile:
138 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 145</p>
139 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 146
147<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile">
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
140 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 153 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
141</pre> 154</pre>
142 155
143<p> 156<p>
144As 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
145<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
146the <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
147you update Portage! 160you update Portage!
148</p> 161</p>
149 162
150<p> 163<p>
219</pre> 232</pre>
220 233
221</body> 234</body>
222</subsection> 235</subsection>
223<subsection> 236<subsection>
224<title>Inheriting USE-flags</title> 237<title>Automatic USE Flags</title>
225<body> 238<body>
226 239
227<p> 240<p>
228Some packages don't only listen to USE-flags, but also provide USE-flags. When 241After certain packages are installed, additional USE flags will automatically
229you install such a package, the USE-flag they provide is added to your USE 242be enabled for you if you do not explicitly disable them. To view the list
230setting. To view the list of packages that provide a USE-flag, check 243of packages that trigger automatic USE-flags, check
231<path>/etc/make.profile/use.defaults</path>: 244<path>/etc/make.profile/use.defaults</path> and the <path>use.defaults</path>
245files of the parent profiles.
232</p> 246</p>
233 247
234<pre caption="A snippet from /etc/make.profile/use.defaults"> 248<pre caption="A snippet from /etc/make.profile/use.defaults">
235gnome gnome-base/gnome 249gnome gnome-base/gnome
236gtk x11-libs/gtk+ 250gtk x11-libs/gtk+
245<title>Precedence</title> 259<title>Precedence</title>
246<body> 260<body>
247 261
248<p> 262<p>
249Of course there is a certain precedence on what setting has priority over the 263Of 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 264USE 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 265<c>java</c> is still used due to a setting that has a higher priority.
266The precedence for the USE setting is, ordered
252by priority (first has lowest priority): 267by priority (first has lowest priority):
253</p> 268</p>
254 269
255<ol> 270<ol>
256 <li> 271 <li>
257 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 272 Default USE setting declared in the <path>make.defaults</path> files part of
258 </li> 273 your profile
259 <li> 274 </li>
260 Inherited USE setting if a package from 275 <li>
261 <path>/etc/make.profile/use.defaults</path> is installed 276 Inherited USE setting if a package from profile <path>use.defaults</path> is installed
262 </li> 277 </li>
263 <li> 278 <li>
264 User-defined USE setting in <path>/etc/make.conf</path> 279 User-defined USE setting in <path>/etc/make.conf</path>
265 </li> 280 </li>
266 <li> 281 <li>
270 User-defined USE setting as environment variable 285 User-defined USE setting as environment variable
271 </li> 286 </li>
272</ol> 287</ol>
273 288
274<p> 289<p>
275To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 290To 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 291--info</c>. This will list all relevant variables (including the <c>USE</c>
277the content used by Portage. 292variable) with the content used by Portage.
278</p> 293</p>
279 294
280<pre caption="Running emerge info"> 295<pre caption="Running emerge --info">
281# <i>emerge info</i> 296# <i>emerge --info</i>
282</pre> 297</pre>
283 298
284</body> 299</body>
285</subsection> 300</subsection>
286<subsection> 301<subsection>
301were emerged on your "old" system but that have been obsoleted by the new USE 316were emerged on your "old" system but that have been obsoleted by the new USE
302flags. 317flags.
303</p> 318</p>
304 319
305<warn> 320<warn>
306Running <c>emerge depclean</c> is a dangerous operation and should be handled 321Running <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 322with 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 323it 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. 324<c>-p</c> switch to have depclean only list the packages without removing them.
310</warn> 325</warn>
311 326
312<pre caption="Removing obsoleted packages"> 327<pre caption="Removing obsoleted packages">
313# <i>emerge -p depclean</i> 328# <i>emerge -p --depclean</i>
314</pre> 329</pre>
315 330
316<p> 331<p>
317When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 332When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
318applications that are dynamically linked against shared objects provided by 333applications that are dynamically linked against shared objects provided by
353-moznocompose -moznoxft 368-moznocompose -moznoxft
354</pre> 369</pre>
355 370
356<p> 371<p>
357<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 372<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 373dedicated to package information called <c>equery</c> which resides in the
359<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 374<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
360</p> 375</p>
361 376
362<pre caption="Installing gentoolkit"> 377<pre caption="Installing gentoolkit">
363# <i>emerge gentoolkit</i> 378# <i>emerge gentoolkit</i>
364</pre> 379</pre>
365 380
366<p> 381<p>
367Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 382Now 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: 383certain package. For instance, for the <c>gnumeric</c> package:
369</p> 384</p>
370 385
371<pre caption="Using etcat to view used USE-flags"> 386<pre caption="Using equery to view used USE-flags">
372# <i>etcat uses gnumeric</i> 387# <i>equery uses gnumeric</i>
373[ Colour Code : <i>set</i> <comment>unset</comment> ] 388[ Colour Code : <i>set</i> <comment>unset</comment> ]
374[ Legend : (U) Col 1 - Current USE flags ] 389[ Legend : (U) Col 1 - Current USE flags ]
375[ : (I) Col 2 - Installed With USE flags ] 390[ : (I) Col 2 - Installed With USE flags ]
376 391
377 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 392 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ]

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