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2<!DOCTYPE sections SYSTEM "/dtd/book.dtd">
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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 1.38 2006/01/13 22:15:20 neysx Exp $ -->
5 8
6<sections> 9<sections>
10
11<version>1.32</version>
12<date>2006-01-13</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>
85A list of available global USE-flags can be found <uri 92A list of available global USE-flags can be found <uri
86link="/dyn/use-index.xml">online</uri> or locally in 93link="/dyn/use-index.xml">online</uri> or locally in
87<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 94<path>/usr/portage/profiles/use.desc</path>.
88snippet: 95</p>
96
89</p> 97<p>
90 98A list of available local USE-flags can be found locally in
91<pre caption="A short snippet of available USE-flags"> 99<path>/usr/portage/profiles/use.local.desc</path>.
92gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
93gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
94gtkhtml - Adds support for gnome-extra/gtkhtml
95guile - Adds support for dev-util/guile (interpreter for Scheme)
96icc - Use the Intel C++ Compiler if the package supports it
97icc-pgo - Enable PGO data generation or use when use icc.
98imap - Adds support for IMAP
99</pre> 100</p>
100 101
101</body> 102</body>
102</subsection> 103</subsection>
103</section> 104</section>
104<section> 105<section>
115<p> 116<p>
116As previously mentioned, all USE-flags are declared inside the <c>USE</c> 117As 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 118variable. 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 119provide 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 120we 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 121in the <path>make.defaults</path> files part of your profile.
121this default setting: 122</p>
123
122</p> 124<p>
125The profile your system listens to is pointed to by the
126<path>/etc/make.profile</path> symlink. Each profile works on top of another,
127larger profile, the end result is therefore the sum of all profiles. The top
128profile is the <path>base</path> profile
129(<path>/usr/portage/profiles/base</path>).
130</p>
123 131
124<pre caption="/etc/make.profile/make.defaults USE variable"> 132<p>
125USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm gtk 133Let us take a look at this default setting for the 2004.3 profile:
126 imlib jpeg kde gnome libg++ libwww mad mikmod motif mpeg ncurses nls 134</p>
127 oggvorbis opengl pam pdflib png python qt quicktime readline sdl slang 135
136<pre caption="Cumulative make.defaults USE variable for the 2004.3 profile">
137<comment>(This example is the sum of the settings in base, default-linux,
138 default-linux/x86 and default-linux/x86/2004.3)</comment>
139USE="x86 oss apm arts avi berkdb bitmap-fonts crypt cups encode fortran f77
140 foomaticdb gdbm gif gpm gtk imlib jpeg kde gnome libg++ libwww mad
141 mikmod motif mpeg ncurses nls oggvorbis opengl pam pdflib png python qt
128 spell ssl svga tcpd truetype X xml2 xmms xv zlib" 142 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
129</pre> 143</pre>
130 144
131<p> 145<p>
132As you can see, this variable already contains quite a lot of keywords. Do 146As 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 147<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 148the <c>USE</c> variable to your needs: changes in this file will be undone when
135you update Portage! 149you update Portage!
136</p> 150</p>
137 151
138<p> 152<p>
153</pre> 167</pre>
154 168
155</body> 169</body>
156</subsection> 170</subsection>
157<subsection> 171<subsection>
172<title>Declaring USE flags for individual packages</title>
173<body>
174
175<p>
176Sometimes you want to declare a certain USE flag for one (or a couple) of
177applications but not system-wide. To accomplish this, you will need to create
178the <path>/etc/portage</path> directory (if it doesn't exist yet) and edit
179<path>/etc/portage/package.use</path>.
180</p>
181
182<p>
183For instance, if you don't want <c>berkdb</c> support globally but you do want
184it for <c>mysql</c>, you would add:
185</p>
186
187<pre caption="/etc/portage/package.use example">
188dev-db/mysql berkdb
189</pre>
190
191<p>
192You can of course also explicitly <e>disable</e> USE flags for a certain
193application. For instance, if you don't want <c>java</c> support in PHP:
194</p>
195
196<pre caption="/etc/portage/package.use 2nd example">
197dev-php/php -java
198</pre>
199
200</body>
201</subsection>
202<subsection>
158<title>Declare temporary USE-flags</title> 203<title>Declare temporary USE-flags</title>
159<body> 204<body>
160 205
161<p> 206<p>
162Sometimes you want to set a certain USE-setting only once. Instead of editing 207Sometimes 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 208<path>/etc/make.conf</path> twice (to do and undo the USE-changes) you can just
164declare the USE-variable as environment variable. 209declare the USE-variable as environment variable. Remember that, when you
210re-emerge or update this application (either explicitly or as part of a system
211update) your changes will be lost!
165</p> 212</p>
166 213
167<p> 214<p>
168As an example we will temporarily remove java from the USE-setting 215As an example we will temporarily remove java from the USE-setting
169during the installation of mozilla. 216during the installation of mozilla.
170</p> 217</p>
171 218
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"> 219<pre caption="Using USE as environment variable">
178# <i>USE="-java" emerge mozilla</i> 220# <i>USE="-java" emerge mozilla</i>
179</pre> 221</pre>
180 222
181</body> 223</body>
182</subsection> 224</subsection>
183<subsection> 225<subsection>
184<title>Inheriting USE-flags</title> 226<title>Automatic USE Flags</title>
185<body> 227<body>
186 228
187<p> 229<p>
188Some packages don't only listen to USE-flags, but also provide USE-flags. When 230After certain packages are installed, additional USE flags will automatically
189you install such a package, the USE-flag they provide is added to your USE 231be enabled for you if you do not explicitly disable them. To view the list
190setting. To view the list of packages that provide a USE-flag, check 232of packages that trigger automatic USE-flags, check
191<path>/etc/make.profile/use.defaults</path>: 233<path>/etc/make.profile/use.defaults</path> and the <path>use.defaults</path>
234files of the parent profiles.
192</p> 235</p>
193 236
194<pre caption="A snippet from /etc/make.profile/use.defaults"> 237<pre caption="A snippet from /etc/make.profile/use.defaults">
195gnome gnome-base/gnome 238gnome gnome-base/gnome
196gtk x11-libs/gtk+ 239gtk x11-libs/gtk+
200</pre> 243</pre>
201 244
202</body> 245</body>
203</subsection> 246</subsection>
204<subsection> 247<subsection>
205<title>Precendence</title> 248<title>Precedence</title>
206<body> 249<body>
207 250
208<p> 251<p>
209Of course there is a certain precendence on what setting has priority over the 252Of 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 253USE 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 254<c>java</c> is still used due to a setting that has a higher priority.
255The precedence for the USE setting is, ordered
212by priority (first has lowest priority): 256by priority (first has lowest priority):
213</p> 257</p>
214 258
215<ol> 259<ol>
216 <li> 260 <li>
217 Default USE setting declared in <path>/etc/make.profile/make.defaults</path> 261 Default USE setting declared in the <path>make.defaults</path> files part of
218 </li> 262 your profile
219 <li> 263 </li>
220 Inherited USE setting if a package from 264 <li>
221 <path>/etc/make.profile/use.defaults</path> is installed 265 Inherited USE setting if a package from profile <path>use.defaults</path>
266 is installed
222 </li> 267 </li>
223 <li> 268 <li>
224 User-defined USE setting in <path>/etc/make.conf</path> 269 User-defined USE setting in <path>/etc/make.conf</path>
225 </li> 270 </li>
226 <li> 271 <li>
272 User-defined USE setting in <path>/etc/portage/package.use</path>
273 </li>
274 <li>
227 User-defined USE setting as environment variable 275 User-defined USE setting as environment variable
228 </li> 276 </li>
229</ol> 277</ol>
230 278
231<p> 279<p>
232To view the final <c>USE</c> setting as seen by Portage, run <c>emerge info</c>. 280To 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 281--info</c>. This will list all relevant variables (including the <c>USE</c>
234the content used by Portage. 282variable) with the content used by Portage.
235</p> 283</p>
236 284
237<pre caption="Running emerge info"> 285<pre caption="Running emerge --info">
238# <i>emerge info</i> 286# <i>emerge --info</i>
287</pre>
288
289</body>
290</subsection>
291<subsection>
292<title>Adapting your Entire System to New USE Flags</title>
293<body>
294
295<p>
296If you have altered your USE flags and you wish to update your entire system to
297use the new USE flags, use <c>emerge</c>'s <c>--newuse</c> option:
239</pre> 298</p>
299
300<pre caption="Rebuilding your entire system">
301# <i>emerge --update --deep --newuse world</i>
302</pre>
303
304<p>
305Next, run Portage's depclean to remove the conditional dependencies that
306were emerged on your "old" system but that have been obsoleted by the new USE
307flags.
308</p>
309
310<warn>
311Running <c>emerge --depclean</c> is a dangerous operation and should be handled
312with care. Double-check the provided list of "obsoleted" packages to make sure
313it doesn't remove packages you need. In the following example we add the
314<c>-p</c> switch to have depclean only list the packages without removing them.
315</warn>
316
317<pre caption="Removing obsoleted packages">
318# <i>emerge -p --depclean</i>
319</pre>
320
321<p>
322When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
323applications that are dynamically linked against shared objects provided by
324possibly removed packages. <c>revdep-rebuild</c> is part of the
325<c>gentoolkit</c> package; don't forget to emerge it first.
326</p>
327
328<pre caption="Running revdep-rebuild">
329# <i>revdep-rebuild</i>
330</pre>
331
332<p>
333When all this is accomplished, your system is using the new USE flag settings.
334</p>
240 335
241</body> 336</body>
242</subsection> 337</subsection>
243</section> 338</section>
244<section> 339<section>
246<subsection> 341<subsection>
247<title>Viewing available USE-flags</title> 342<title>Viewing available USE-flags</title>
248<body> 343<body>
249 344
250<p> 345<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 346Let 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 347find out, we use <c>emerge</c> with the <c>--pretend</c> and <c>--verbose</c>
260anything) and <c>--verbose</c> (give more output) options: 348options:
261</p> 349</p>
262 350
263<pre caption="Viewing the used USE-flags"> 351<pre caption="Viewing the used USE-flags">
264# <i>emerge --pretend --verbose mozilla</i> 352# <i>emerge --pretend --verbose mozilla</i>
265These are the packages that I would merge, in order: 353These are the packages that I would merge, in order:
266 354
267Calculating dependencies ...done! 355Calculating dependencies ...done!
268[ebuild N ] net-www/mozilla-1.5-r1 +java +crypt -ipv6 -gtk2 +ssl +ldap 356[ebuild R ] www-client/mozilla-1.7.12-r2 USE="crypt gnome java mozsvg ssl
269+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 357truetype xprint -debug -ipv6 -ldap -mozcalendar -mozdevelop -moznocompose
270-moznocompose -moznoxft 358-moznoirc -moznomail -moznoxft -postgres -xinerama" 0 kB
271</pre> 359</pre>
272 360
273<p> 361<p>
274<c>emerge</c> isn't the only tool for this job. In fact, we have a tool 362<c>emerge</c> isn't the only tool for this job. In fact, we have a tool
275dedicated to package information called <c>etcat</c> which resides in the 363dedicated to package information called <c>equery</c> which resides in the
276<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 364<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
277</p> 365</p>
278 366
279<pre caption="Installing gentoolkit"> 367<pre caption="Installing gentoolkit">
280# <i>emerge --usepkg gentoolkit</i> 368# <i>emerge gentoolkit</i>
281</pre> 369</pre>
282 370
283<p> 371<p>
284Now run <c>etcat</c> with the <c>uses</c> argument to view the USE-flags of a 372Now run <c>equery</c> with the <c>uses</c> argument to view the USE-flags of a
285certain package. For instance, for the <c>gnumeric</c> package: 373certain package. For instance, for the <c>gnumeric</c> package:
286</p> 374</p>
287 375
288<pre caption="Using etcat to view used USE-flags"> 376<pre caption="Using equery to view used USE-flags">
289# <i>etcat uses gnumeric</i> 377# <i>equery uses gnumeric</i>
290[ Colour Code : <i>set</i> <comment>unset</comment> ] 378[ Colour Code : <i>set</i> <comment>unset</comment> ]
291[ Legend : (U) Col 1 - Current USE flags ] 379[ Legend : (U) Col 1 - Current USE flags ]
292[ : (I) Col 2 - Installed With USE flags ] 380[ : (I) Col 2 - Installed With USE flags ]
293 381
294 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ] 382 U I [ Found these USE variables in : app-office/gnumeric-1.2.0 ]

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