file manipulation

       fakeroot [-l|--lib library] [--faked faked-binary] [-i  load-file]  [-s
       save-file]   [-u|--unknown-is-real   ]  [-b|--fd-base  ]  [-h|--help  ]
       [-v|--version ] [--] [command]

       fakeroot runs a command in an environment wherein it  appears  to  have
       root  privileges  for  file  manipulation.  This is useful for allowing
       users to create archives (tar, ar, .deb etc.) with files in  them  with
       root  permissions/ownership.   Without  fakeroot one would need to have
       root privileges to create the constituent files of  the  archives  with
       the  correct  permissions  and ownership, and then pack them up, or one
       would have to  construct  the  archives  directly,  without  using  the

       fakeroot  works  by  replacing  the file manipulation library functions
       (chmod(2), stat(2) etc.) by ones that  simulate  the  effect  the  real
       library  functions would have had, had the user really been root. These
       wrapper functions are  in  a  shared  library  /usr/lib/libfakeroot.so*
       which is loaded through the LD_PRELOAD mechanism of the dynamic loader.
       (See ld.so(8))

       If you intend to build packages with fakeroot, please try building  the
       fakeroot  package first: the "debian/rules build" stage has a few tests
       (testing mostly for bugs in old fakeroot versions). If those tests fail
       (for  example  because you have certain libc5 programs on your system),
       other packages you build with fakeroot will quite likely fail too,  but
       possibly in much more subtle ways.

       Also,  note that it's best not to do the building of the binaries them-
       selves under fakeroot. Especially configure and friends don't  like  it
       when  the  system  suddenly  behaves differently from what they expect.
       (or, they randomly unset some  environment  variables,  some  of  which
       fakeroot needs).

       -l library, --lib library
              Specify an alternative wrapper library.

       --faked binary
              Specify an alternative binary to use as faked.

       [--] command
              Any  command  you want to be ran as fakeroot. Use '--' if in the
              command you have  other  options  that  may  confuse  fakeroot's
              option parsing.

       -s save-file
              Save  the  fakeroot  environment to save-file on exit. This file
              can be used to restore the environment later using -i.  However,
              this  file will leak and fakeroot will behave in odd ways unless

       -u, --unknown-is-real
              Use the real ownership of files previously unknown  to  fakeroot
              instead of pretending they are owned by root:root.

       -b fd  Specify fd base (TCP mode only). fd is the minimum file descrip-
              tor number to use for TCP connections; this may be important  to
              avoid  conflicts  with the file descriptors used by the programs
              being run under fakeroot.

       -h     Display help.

       -v     Display version.

       Here is an example session with fakeroot.  Notice that inside the  fake
       root  environment  file manipulation that requires root privileges suc-
       ceeds, but is not really happening.

       $  whoami
       $ fakeroot /bin/bash
       #  whoami
       # mknod hda3 b 3 1
       # ls -ld hda3
       brw-r--r--   1 root     root       3,   1 Jul  2 22:58 hda3
       # chown joost:root hda3
       # ls -ld hda3
       brw-r--r--   1 joost    root       3,   1 Jul  2 22:58 hda3
       # ls -ld /
       drwxr-xr-x  20 root     root         1024 Jun 17 21:50 /
       # chown joost:users /
       # chmod a+w /
       # ls -ld /
       drwxrwxrwx  20 joost    users        1024 Jun 17 21:50 /
       # exit
       $ ls -ld /
       drwxr-xr-x  20 root     root         1024 Jun 17 21:50 //
       $ ls -ld hda3
       -rw-r--r--   1 joost    users           0 Jul  2 22:58 hda3

       Only the effects that user joost could do anyway happen for real.

       fakeroot was specifically written to  enable  users  to  create  Debian
       GNU/Linux  packages  (in  the  deb(5)  format) without giving them root
       privileges.  This  can  be  done  by  commands  like  dpkg-buildpackage
       -rfakeroot  or  debuild  -rfakeroot (actually, -rfakeroot is default in
       debuild nowadays, so you don't need that argument).

       fakeroot is a regular, non-setuid program. It does not enhance a user's
       privileges, or decrease the system's security.
              started by the same user).


              Fakeroot  is  implemented  by  wrapping  system  calls.  This is
              accomplished by  setting  LD_LIBRARY_PATH=/usr/lib/fakeroot  and
              LD_PRELOAD=libfakeroot.so.0.   That library is loaded before the
              system's C library, and so most of  the  library  functions  are
              intercepted by it.  If you need to set either LD_LIBRARY_PATH or
              LD_PRELOAD from within a fakeroot environment, it should be  set
              relative      to      the      given      paths,      as      in

       Library versions
              Every command executed within fakeroot needs to be linked to the
              same version of the C library as fakeroot itself.

              fakeroot  doesn't  wrap open(), create(), etc. So, if user joost
              does either

              touch foo
              ls -al foo

              or the other way around,

              touch foo
              ls -al foo

              fakeroot has no way of knowing that in the first case, the owner
              of  foo  really  should be joost while the second case it should
              have been root.  For the Debian packaging, defaulting to  giving
              all "unknown" files uid=gid=0, is always OK. The real way around
              this is to wrap open() and  create(),  but  that  creates  other
              problems, as demonstrated by the libtricks package. This package
              wrapped many more functions, and tried to do  a  lot  more  than
              fakeroot .  It turned out that a minor upgrade of libc (from one
              where the stat() function didn't use open() to one with a stat()
              function that did (in some cases) use open()), would cause unex-
              plainable segfaults  (that  is,  the  libc6  stat()  called  the
              wrapped  open(),  which  would then call the libc6 stat(), etc).
              Fixing them wasn't all that easy, but once fixed, it was just  a
              matter  of  time  before another function started to use open(),
              never mind trying to port it to a  different  operating  system.
              Thus  I decided to keep the number of functions wrapped by fake-
              root as small as possible, to limit the  likelihood  of  'colli-

       GNU configure (and other such programs)
       of the file will be 000. The bug is that if root does the same,  open()
       will succeed, as the file permissions aren't checked at all for root. I
       choose not to wrap open(), as open() is used by many other functions in
       libc  (also  those  that  are already wrapped), thus creating loops (or
       possible future loops, when the implementation of  various  libc  func-
       tions slightly change).

       fakeroot is distributed under the GNU General Public License.  (GPL 2.0
       or greater).

       joost witteveen

       Clint Adams

       Timo Savola

       mostly by J.H.M. Dassen <jdassen@debian.org> Rather  a  lot  mods/addi-
       tions by joost and Clint.

       faked(1) dpkg-buildpackage(1), debuild(1) /usr/share/doc/fakeroot/DEBUG

Debian Project                   6 August 2004                     fakeroot(1)
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