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7<!-- $Header: /var/cvsroot/gentoo/xml/htdocs/doc/en/handbook/hb-working-use.xml,v 1.17 2004/08/01 13:08:35 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>
99icc - Use the Intel C++ Compiler if the package supports it 103icc - Use the Intel C++ Compiler if the package supports it
100icc-pgo - Enable PGO data generation or use when use icc. 104icc-pgo - Enable PGO data generation or use when use icc.
101imap - Adds support for IMAP 105imap - Adds support for IMAP
102</pre> 106</pre>
103 107
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
104</body> 113</body>
105</subsection> 114</subsection>
106</section> 115</section>
107<section> 116<section>
108<title>Using USE-flags</title> 117<title>Using USE-flags</title>
118<p> 127<p>
119As 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>
120variable. 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
121provide 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
122we 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
123in 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.
124this default setting: 133</p>
134
125</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>
126 142
127<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 143<p>
128USE="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:
129 gtk gtk2 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses 145</p>
130 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
131 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"
132</pre> 154</pre>
133 155
134<p> 156<p>
135As 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
136<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
137the <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
138you update Portage! 160you update Portage!
139</p> 161</p>
140 162
141<p> 163<p>
153 175
154<pre caption="An example USE setting in /etc/make.conf"> 176<pre caption="An example USE setting in /etc/make.conf">
155USE="-kde -qt ldap" 177USE="-kde -qt ldap"
156</pre> 178</pre>
157 179
180</body>
181</subsection>
182<subsection>
183<title>Declaring USE flags for individual packages</title>
184<body>
185
158<p> 186<p>
159Sometimes 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
160applications 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
161the <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
162<path>/etc/portage/package.use</path>. 190<path>/etc/portage/package.use</path>.
197<p> 225<p>
198As an example we will temporarily remove java from the USE-setting 226As an example we will temporarily remove java from the USE-setting
199during the installation of mozilla. 227during the installation of mozilla.
200</p> 228</p>
201 229
202<note>
203The <c>emerge</c> command will be discussed more thoroughly in <uri
204link="?part=2&amp;chap=2">Portage and Software</uri>.
205</note>
206
207<pre caption="Using USE as environment variable"> 230<pre caption="Using USE as environment variable">
208# <i>USE="-java" emerge mozilla</i> 231# <i>USE="-java" emerge mozilla</i>
209</pre> 232</pre>
210 233
211</body> 234</body>
212</subsection> 235</subsection>
213<subsection> 236<subsection>
214<title>Inheriting USE-flags</title> 237<title>Automatic USE Flags</title>
215<body> 238<body>
216 239
217<p> 240<p>
218Some packages don't only listen to USE-flags, but also provide USE-flags. When 241After certain packages are installed, additional USE flags will automatically
219you 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
220setting. To view the list of packages that provide a USE-flag, check 243of packages that trigger automatic USE-flags, check
221<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.
222</p> 246</p>
223 247
224<pre caption="A snippet from /etc/make.profile/use.defaults"> 248<pre caption="A snippet from /etc/make.profile/use.defaults">
225gnome gnome-base/gnome 249gnome gnome-base/gnome
226gtk x11-libs/gtk+ 250gtk x11-libs/gtk+
235<title>Precedence</title> 259<title>Precedence</title>
236<body> 260<body>
237 261
238<p> 262<p>
239Of 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
240USE 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
241<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
242by priority (first has lowest priority): 267by priority (first has lowest priority):
243</p> 268</p>
244 269
245<ol> 270<ol>
246 <li> 271 <li>
247 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
248 </li> 273 your profile
249 <li> 274 </li>
250 Inherited USE setting if a package from 275 <li>
251 <path>/etc/make.profile/use.defaults</path> is installed 276 Inherited USE setting if a package from profile <path>use.defaults</path> is installed
252 </li> 277 </li>
253 <li> 278 <li>
254 User-defined USE setting in <path>/etc/make.conf</path> 279 User-defined USE setting in <path>/etc/make.conf</path>
255 </li> 280 </li>
256 <li> 281 <li>
260 User-defined USE setting as environment variable 285 User-defined USE setting as environment variable
261 </li> 286 </li>
262</ol> 287</ol>
263 288
264<p> 289<p>
265To 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
266This 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>
267the content used by Portage. 292variable) with the content used by Portage.
268</p> 293</p>
269 294
270<pre caption="Running emerge info"> 295<pre caption="Running emerge --info">
271# <i>emerge info</i> 296# <i>emerge --info</i>
272</pre> 297</pre>
273 298
274</body> 299</body>
275</subsection> 300</subsection>
276<subsection> 301<subsection>
277<title>Adapting your Entire System to New USE Flags</title> 302<title>Adapting your Entire System to New USE Flags</title>
278<body> 303<body>
279 304
280<p> 305<p>
281If 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
282use 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:
283Note however that these steps will take a long time to finish and that work is
284on the way to adjust Portage to handle this behaviour quicker and automatically.
285</p>
286
287<p>
288First of all, rebuild your entire system using the new USE flags:
289</p> 308</p>
290 309
291<pre caption="Rebuilding your entire system"> 310<pre caption="Rebuilding your entire system">
292# <i>emerge --emptytree world</i> 311# <i>emerge --update --deep --newuse world</i>
293</pre> 312</pre>
294 313
295<p> 314<p>
296Next, run Portage' depclean to remove the conditional dependencies that 315Next, run Portage's depclean to remove the conditional dependencies that
297were 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
298flags. 317flags.
299</p> 318</p>
300 319
301<warn> 320<warn>
302Running <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
303with 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
304it 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
305<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.
306</warn> 325</warn>
307 326
308<pre caption="Removing obsoleted packages"> 327<pre caption="Removing obsoleted packages">
309# <i>emerge -p depclean</i> 328# <i>emerge -p --depclean</i>
310</pre> 329</pre>
311 330
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.
312<p> 336</p>
337
338<pre caption="Running revdep-rebuild">
339# <i>revdep-rebuild</i>
340</pre>
341
342<p>
313When 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.
314</p> 344</p>
315 345
316</body> 346</body>
317</subsection> 347</subsection>
318</section> 348</section>
321<subsection> 351<subsection>
322<title>Viewing available USE-flags</title> 352<title>Viewing available USE-flags</title>
323<body> 353<body>
324 354
325<p> 355<p>
326In the next chapter on <uri link="?part=2&amp;chap=2">Portage and Software</uri>
327we will explain how to manage your installed software and how to work with
328<c>emerge</c>. However, we will give you a primer on <c>emerge</c> by showing
329you how to view what USE-flags a package uses.
330</p>
331
332<p>
333Let 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
334find 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>
335anything) and <c>--verbose</c> (give more output) options: 358options:
336</p> 359</p>
337 360
338<pre caption="Viewing the used USE-flags"> 361<pre caption="Viewing the used USE-flags">
339# <i>emerge --pretend --verbose mozilla</i> 362# <i>emerge --pretend --verbose mozilla</i>
340These are the packages that I would merge, in order: 363These are the packages that I would merge, in order:
345-moznocompose -moznoxft 368-moznocompose -moznoxft
346</pre> 369</pre>
347 370
348<p> 371<p>
349<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
350dedicated to package information called <c>etcat</c> which resides in the 373dedicated to package information called <c>equery</c> which resides in the
351<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 374<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
352</p> 375</p>
353 376
354<pre caption="Installing gentoolkit"> 377<pre caption="Installing gentoolkit">
355# <i>emerge --usepkg gentoolkit</i> 378# <i>emerge gentoolkit</i>
356</pre> 379</pre>
357 380
358<p> 381<p>
359Now 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
360certain package. For instance, for the <c>gnumeric</c> package: 383certain package. For instance, for the <c>gnumeric</c> package:
361</p> 384</p>
362 385
363<pre caption="Using etcat to view used USE-flags"> 386<pre caption="Using equery to view used USE-flags">
364# <i>etcat uses gnumeric</i> 387# <i>equery uses gnumeric</i>
365[ Colour Code : <i>set</i> <comment>unset</comment> ] 388[ Colour Code : <i>set</i> <comment>unset</comment> ]
366[ Legend : (U) Col 1 - Current USE flags ] 389[ Legend : (U) Col 1 - Current USE flags ]
367[ : (I) Col 2 - Installed With USE flags ] 390[ : (I) Col 2 - Installed With USE flags ]
368 391
369 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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