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7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.18 2004/09/11 14:05:49 swift 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
11<version>1.31</version>
12<date>2005-10-26</date>
13
10<section> 14<section>
11<title>What are USE-flags?</title> 15<title>What are USE-flags?</title>
12<subsection> 16<subsection>
13<title>The ideas behind USE-flags</title> 17<title>The ideas behind USE-flags</title>
14<body> 18<body>
123<p> 127<p>
124As 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>
125variable. 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
126provide 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
127we 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
128in 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.
129this default setting: 133</p>
134
130</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>
131 142
132<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 143<p>
133USE="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:
134 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 145</p>
135 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
136 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"
137</pre> 154</pre>
138 155
139<p> 156<p>
140As 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
141<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
142the <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
143you update Portage! 160you update Portage!
144</p> 161</p>
145 162
146<p> 163<p>
158 175
159<pre caption="An example USE setting in /etc/make.conf"> 176<pre caption="An example USE setting in /etc/make.conf">
160USE="-kde -qt ldap" 177USE="-kde -qt ldap"
161</pre> 178</pre>
162 179
180</body>
181</subsection>
182<subsection>
183<title>Declaring USE flags for individual packages</title>
184<body>
185
163<p> 186<p>
164Sometimes you want to declare a certain USE flag for one (or a couple) of 187Sometimes you want to declare a certain USE flag for one (or a couple) of
165applications but not system-wide. To accomplish this, you will need to create 188applications but not system-wide. To accomplish this, you will need to create
166the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit 189the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
167<path>/etc/portage/package.use</path>. 190<path>/etc/portage/package.use</path>.
202<p> 225<p>
203As an example we will temporarily remove java from the USE-setting 226As an example we will temporarily remove java from the USE-setting
204during the installation of mozilla. 227during the installation of mozilla.
205</p> 228</p>
206 229
207<note>
208The <c>emerge</c> command will be discussed more thoroughly in <uri
209link="?part=2&amp;chap=2">Portage and Software</uri>.
210</note>
211
212<pre caption="Using USE as environment variable"> 230<pre caption="Using USE as environment variable">
213# <i>USE="-java" emerge mozilla</i> 231# <i>USE="-java" emerge mozilla</i>
214</pre> 232</pre>
215 233
216</body> 234</body>
217</subsection> 235</subsection>
218<subsection> 236<subsection>
219<title>Inheriting USE-flags</title> 237<title>Automatic USE Flags</title>
220<body> 238<body>
221 239
222<p> 240<p>
223Some packages don't only listen to USE-flags, but also provide USE-flags. When 241After certain packages are installed, additional USE flags will automatically
224you 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
225setting. To view the list of packages that provide a USE-flag, check 243of packages that trigger automatic USE-flags, check
226<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.
227</p> 246</p>
228 247
229<pre caption="A snippet from /etc/make.profile/use.defaults"> 248<pre caption="A snippet from /etc/make.profile/use.defaults">
230gnome gnome-base/gnome 249gnome gnome-base/gnome
231gtk x11-libs/gtk+ 250gtk x11-libs/gtk+
240<title>Precedence</title> 259<title>Precedence</title>
241<body> 260<body>
242 261
243<p> 262<p>
244Of 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
245USE 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
246<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
247by priority (first has lowest priority): 267by priority (first has lowest priority):
248</p> 268</p>
249 269
250<ol> 270<ol>
251 <li> 271 <li>
252 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
253 </li> 273 your profile
254 <li> 274 </li>
255 Inherited USE setting if a package from 275 <li>
256 <path>/etc/make.profile/use.defaults</path> is installed 276 Inherited USE setting if a package from profile <path>use.defaults</path> is installed
257 </li> 277 </li>
258 <li> 278 <li>
259 User-defined USE setting in <path>/etc/make.conf</path> 279 User-defined USE setting in <path>/etc/make.conf</path>
260 </li> 280 </li>
261 <li> 281 <li>
265 User-defined USE setting as environment variable 285 User-defined USE setting as environment variable
266 </li> 286 </li>
267</ol> 287</ol>
268 288
269<p> 289<p>
270To 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
271This 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>
272the content used by Portage. 292variable) with the content used by Portage.
273</p> 293</p>
274 294
275<pre caption="Running emerge info"> 295<pre caption="Running emerge --info">
276# <i>emerge info</i> 296# <i>emerge --info</i>
277</pre> 297</pre>
278 298
279</body> 299</body>
280</subsection> 300</subsection>
281<subsection> 301<subsection>
282<title>Adapting your Entire System to New USE Flags</title> 302<title>Adapting your Entire System to New USE Flags</title>
283<body> 303<body>
284 304
285<p> 305<p>
286If you have altered your USE flags and you wish to update your entire system to 306If you have altered your USE flags and you wish to update your entire system to
287use the new USE flags, you can try following the next steps to accomplish this. 307use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
288Note however that these steps will take a long time to finish and that work is
289on the way to adjust Portage to handle this behaviour quicker and automatically.
290</p>
291
292<p>
293First of all, rebuild your entire system using the new USE flags:
294</p> 308</p>
295 309
296<pre caption="Rebuilding your entire system"> 310<pre caption="Rebuilding your entire system">
297# <i>emerge --emptytree world</i> 311# <i>emerge --update --deep --newuse world</i>
298</pre> 312</pre>
299 313
300<p> 314<p>
301Next, run Portage' depclean to remove the conditional dependencies that 315Next, run Portage's depclean to remove the conditional dependencies that
302were 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
303flags. 317flags.
304</p> 318</p>
305 319
306<warn> 320<warn>
307Running <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
308with 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
309it 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
310<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.
311</warn> 325</warn>
312 326
313<pre caption="Removing obsoleted packages"> 327<pre caption="Removing obsoleted packages">
314# <i>emerge -p depclean</i> 328# <i>emerge -p --depclean</i>
315</pre> 329</pre>
316 330
331<p>
332When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
333applications that are dynamically linked against shared objects provided by
334possibly removed packages. <c>revdep-rebuild</c> is part of the
335<c>gentoolkit</c> package; don't forget to emerge it first.
317<p> 336</p>
337
338<pre caption="Running revdep-rebuild">
339# <i>revdep-rebuild</i>
340</pre>
341
342<p>
318When depclean has finished, your system is using the new USE flag settings. 343When all this is accomplished, your system is using the new USE flag settings.
319</p> 344</p>
320 345
321</body> 346</body>
322</subsection> 347</subsection>
323</section> 348</section>
326<subsection> 351<subsection>
327<title>Viewing available USE-flags</title> 352<title>Viewing available USE-flags</title>
328<body> 353<body>
329 354
330<p> 355<p>
331In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
332we will explain how to manage your installed software and how to work with
333<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
334you how to view what USE-flags a package uses.
335</p>
336
337<p>
338Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To 356Let us take the example of <c>mozilla</c>: what USE-flags does it listen to? To
339find out, we use <c>emerge</c> with the <c>--pretend</c> (don't really do 357find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
340anything) and <c>--verbose</c> (give more output) options: 358options:
341</p> 359</p>
342 360
343<pre caption="Viewing the used USE-flags"> 361<pre caption="Viewing the used USE-flags">
344# <i>emerge --pretend --verbose mozilla</i> 362# <i>emerge --pretend --verbose mozilla</i>
345These are the packages that I would merge, in order: 363These are the packages that I would merge, in order:
350-moznocompose -moznoxft 368-moznocompose -moznoxft
351</pre> 369</pre>
352 370
353<p> 371<p>
354<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
355dedicated to package information called <c>etcat</c> which resides in the 373dedicated to package information called <c>equery</c> which resides in the
356<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 374<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
357</p> 375</p>
358 376
359<pre caption="Installing gentoolkit"> 377<pre caption="Installing gentoolkit">
360# <i>emerge --usepkg gentoolkit</i> 378# <i>emerge gentoolkit</i>
361</pre> 379</pre>
362 380
363<p> 381<p>
364Now 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
365certain package. For instance, for the <c>gnumeric</c> package: 383certain package. For instance, for the <c>gnumeric</c> package:
366</p> 384</p>
367 385
368<pre caption="Using etcat to view used USE-flags"> 386<pre caption="Using equery to view used USE-flags">
369# <i>etcat uses gnumeric</i> 387# <i>equery uses gnumeric</i>
370[ Colour Code : <i>set</i> <comment>unset</comment> ] 388[ Colour Code : <i>set</i> <comment>unset</comment> ]
371[ Legend : (U) Col 1 - Current USE flags ] 389[ Legend : (U) Col 1 - Current USE flags ]
372[ : (I) Col 2 - Installed With USE flags ] 390[ : (I) Col 2 - Installed With USE flags ]
373 391
374 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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