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1/*! \page buildroot Using a build root2 3The build root is very similar to Root: (which is now legacy).4By using Buildroot: in your spec file you are indicating5that your package can be built (installed into and packaged from)6a user-definable directory.  This helps package building by normal7users.8 9\section buildroot_specfile The Spec File10 11Simply use12\verbatim13  Buildroot: <dir>14\endverbatim15 16in your spec file.  The actual buildroot used by RPM during the17build will be available to you (and your %prep, %build, and %install18sections) as the environment variable RPM_BUILD_ROOT.  You must19make sure that the files for the package are installed into the20proper buildroot.  As with Root:, the files listed in the %files21section should *not* contain the buildroot.  For example, the22following hypothetical spec file:23 24\verbatim25  Name: foo26  ...27  Root: /tmp28  29  %prep30  ...31  32  %build33  ...34  35  %install36  install -m755 fooprog /tmp/usr/bin/fooprog37  38  %files39  /usr/bin/fooprog40\endverbatim41 42would be changed to:43 44\verbatim45  Name: foo46  ...47  BuildRoot: /tmp48  49  %prep50  ...51  52  %build53  ...54  55  %install56  install -m755 fooprog $RPM_BUILD_ROOT/usr/bin/fooprog57  58  %files59  /usr/bin/fooprog60\endverbatim61 62\section buildroot_building Building With a Build Root63 64RPM will use the buildroot listed in the spec file as the default65buildroot.  There are two ways to override this.  First, you can66have "buildroot: <dir>" in your rpmrc.  Second, you can override67the default, and any entry in an rpmrc by using "--buildroot <dir>"68on the RPM command line.69 70\section buildroot_caveats Caveats using Build Roots71 72Care should be taken when using buildroots that the install directory73is owned by the correct package.  For example the file74 75\verbatim76	/usr/lib/perl5/site_perl/MD5.pm77\endverbatim78 79is installed by the package perl-MD5.  If we were to use a buildroot80and specified 81 82\verbatim83	%files  84	/usr/lib/perl5/site_perl85\endverbatim86 87we would end up with the directory /usr/lib/perl5/site_perl being88owned by the library package. This directory is in fact used by ALL89perl libraries and should be owned by the package for perl not any of90its libraries. It is important that the %files command specifies all91the known directories explicitly. So this would be preferable:92 93\verbatim94	/usr/lib/perl5/site_perl/*95\endverbatim96 97Since we only want the files and directories that the package perl-MD598installed into /usr/lib/perl5/site_perl/ to be owned by the package.99The directory /usr/lib/perl5/site_perl/ is created when perl is100installed.101 102If we were to use the bad %files line shown above, then when the MD5103package is removed, RPM will try to remove each of the perl-MD5 files and104then try to remove the dir itself. If there's still files in the105site_perl directory (e.g. from other packages) then the Unix rmdir(2)106will fail and you will get a non-zero return code from RPM. If the107rmdir succeeds then you will no longer have a site_perl directory on108your machine even though this directory was created when Perl was109installed.110 111The other common problem is that two packages could install two files112with the the same name into the same directory. This would lead to113other collision problems when removing the file. Care should be taken114by the packager to ensure that all packages install unique files.115Explicit use of %files can help make the packager aware of potential116problems before they happen. When you try to install a package which117contains file names already used by other packages on the system then118RPM will warn you of the problem and give a fatal error. This error can119be overridden with --force and the installed file will be replaced by the120new file and when the new package is removed the file will be removed as well.121 122*/123