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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 1.38 2006/01/13 22:15:20 neysx Exp $ -->
8 8
9<sections> 9<sections>
10 10
11<version>1.21</version> 11<version>1.32</version>
12<date>2004-10-21</date> 12<date>2006-01-13</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>
89</ul> 89</ul>
90 90
91<p> 91<p>
92A list of available global USE-flags can be found <uri 92A list of available global USE-flags can be found <uri
93link="/dyn/use-index.xml">online</uri> or locally in 93link="/dyn/use-index.xml">online</uri> or locally in
94<path>/usr/portage/profiles/use.desc</path>. A short (<e>very</e> incomplete) 94<path>/usr/portage/profiles/use.desc</path>.
95snippet:
96</p>
97
98<pre caption="A short snippet of available USE-flags">
99gtk - Adds support for x11-libs/gtk+ (The GIMP Toolkit)
100gtk2 - Use gtk+-2.0.0 over gtk+-1.2 in cases where a program supports both.
101gtkhtml - Adds support for gnome-extra/gtkhtml
102guile - Adds support for dev-util/guile (interpreter for Scheme)
103icc - Use the Intel C++ Compiler if the package supports it
104icc-pgo - Enable PGO data generation or use when use icc.
105imap - Adds support for IMAP
106</pre> 95</p>
107 96
108<p> 97<p>
109A list of available local USE-flags can be found locally in 98A list of available local USE-flags can be found locally in
110<path>/usr/portage/profiles/use.local.desc</path>. 99<path>/usr/portage/profiles/use.local.desc</path>.
111</p> 100</p>
127<p> 116<p>
128As 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>
129variable. 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
130provide 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
131we 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
132in 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.
133this default setting: 122</p>
123
134</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>
135 131
136<pre caption="/etc/make.profile/make.defaults USE variable on an x86 system"> 132<p>
137USE="x86 oss apm arts avi berkdb crypt cups encode foomaticdb gdbm gif gpm 133Let 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 134</p>
139 nls oggvorbis opengl pam pdflib png python qt quicktime readline sdl 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
140 slang spell ssl svga tcpd truetype X xml2 xmms xv zlib" 142 quicktime readline sdl spell ssl svga tcpd truetype X xml2 xmms xv zlib"
141</pre> 143</pre>
142 144
143<p> 145<p>
144As 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
145<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
146the <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
147you update Portage! 149you update Portage!
148</p> 150</p>
149 151
150<p> 152<p>
219</pre> 221</pre>
220 222
221</body> 223</body>
222</subsection> 224</subsection>
223<subsection> 225<subsection>
224<title>Inheriting USE-flags</title> 226<title>Automatic USE Flags</title>
225<body> 227<body>
226 228
227<p> 229<p>
228Some packages don't only listen to USE-flags, but also provide USE-flags. When 230After certain packages are installed, additional USE flags will automatically
229you 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
230setting. To view the list of packages that provide a USE-flag, check 232of packages that trigger automatic USE-flags, check
231<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.
232</p> 235</p>
233 236
234<pre caption="A snippet from /etc/make.profile/use.defaults"> 237<pre caption="A snippet from /etc/make.profile/use.defaults">
235gnome gnome-base/gnome 238gnome gnome-base/gnome
236gtk x11-libs/gtk+ 239gtk x11-libs/gtk+
245<title>Precedence</title> 248<title>Precedence</title>
246<body> 249<body>
247 250
248<p> 251<p>
249Of course there is a certain precedence on what setting has priority over the 252Of 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 253USE 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 254<c>java</c> is still used due to a setting that has a higher priority.
255The precedence for the USE setting is, ordered
252by priority (first has lowest priority): 256by priority (first has lowest priority):
253</p> 257</p>
254 258
255<ol> 259<ol>
256 <li> 260 <li>
257 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
258 </li> 262 your profile
259 <li> 263 </li>
260 Inherited USE setting if a package from 264 <li>
261 <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
262 </li> 267 </li>
263 <li> 268 <li>
264 User-defined USE setting in <path>/etc/make.conf</path> 269 User-defined USE setting in <path>/etc/make.conf</path>
265 </li> 270 </li>
266 <li> 271 <li>
270 User-defined USE setting as environment variable 275 User-defined USE setting as environment variable
271 </li> 276 </li>
272</ol> 277</ol>
273 278
274<p> 279<p>
275To 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
276This 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>
277the content used by Portage. 282variable) with the content used by Portage.
278</p> 283</p>
279 284
280<pre caption="Running emerge info"> 285<pre caption="Running emerge --info">
281# <i>emerge info</i> 286# <i>emerge --info</i>
282</pre> 287</pre>
283 288
284</body> 289</body>
285</subsection> 290</subsection>
286<subsection> 291<subsection>
301were emerged on your "old" system but that have been obsoleted by the new USE 306were emerged on your "old" system but that have been obsoleted by the new USE
302flags. 307flags.
303</p> 308</p>
304 309
305<warn> 310<warn>
306Running <c>emerge depclean</c> is a dangerous operation and should be handled 311Running <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 312with 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 313it 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. 314<c>-p</c> switch to have depclean only list the packages without removing them.
310</warn> 315</warn>
311 316
312<pre caption="Removing obsoleted packages"> 317<pre caption="Removing obsoleted packages">
313# <i>emerge -p depclean</i> 318# <i>emerge -p --depclean</i>
314</pre> 319</pre>
315 320
316<p> 321<p>
317When depclean has finished, run <c>revdep-rebuild</c> to rebuild the 322When depclean has finished, run <c>revdep-rebuild</c> to rebuild the
318applications that are dynamically linked against shared objects provided by 323applications that are dynamically linked against shared objects provided by
346<pre caption="Viewing the used USE-flags"> 351<pre caption="Viewing the used USE-flags">
347# <i>emerge --pretend --verbose mozilla</i> 352# <i>emerge --pretend --verbose mozilla</i>
348These are the packages that I would merge, in order: 353These are the packages that I would merge, in order:
349 354
350Calculating dependencies ...done! 355Calculating dependencies ...done!
351[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
352+gnome -debug +mozcalendar -mozaccess -mozxmlterm -moznoirc -moznomail 357truetype xprint -debug -ipv6 -ldap -mozcalendar -mozdevelop -moznocompose
353-moznocompose -moznoxft 358-moznoirc -moznomail -moznoxft -postgres -xinerama" 0 kB
354</pre> 359</pre>
355 360
356<p> 361<p>
357<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
358dedicated to package information called <c>etcat</c> which resides in the 363dedicated to package information called <c>equery</c> which resides in the
359<c>gentoolkit</c> package. First, install <c>gentoolkit</c>: 364<c>gentoolkit</c> package. First, install <c>gentoolkit</c>:
360</p> 365</p>
361 366
362<pre caption="Installing gentoolkit"> 367<pre caption="Installing gentoolkit">
363# <i>emerge gentoolkit</i> 368# <i>emerge gentoolkit</i>
364</pre> 369</pre>
365 370
366<p> 371<p>
367Now 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
368certain package. For instance, for the <c>gnumeric</c> package: 373certain package. For instance, for the <c>gnumeric</c> package:
369</p> 374</p>
370 375
371<pre caption="Using etcat to view used USE-flags"> 376<pre caption="Using equery to view used USE-flags">
372# <i>etcat uses gnumeric</i> 377# <i>equery uses gnumeric</i>
373[ Colour Code : <i>set</i> <comment>unset</comment> ] 378[ Colour Code : <i>set</i> <comment>unset</comment> ]
374[ Legend : (U) Col 1 - Current USE flags ] 379[ Legend : (U) Col 1 - Current USE flags ]
375[ : (I) Col 2 - Installed With USE flags ] 380[ : (I) Col 2 - Installed With USE flags ]
376 381
377 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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