xauth - X authority file utility


   xauth [ -f authfile ] [ -vqibn ] [ command arg ... ]


   The  xauth  program  is  used  to  edit  and  display the authorization
   information used in connecting  to  the  X  server.   This  program  is
   usually  used  to  extract  authorization  records from one machine and
   merge them in on another (as is the case when using  remote  logins  or
   granting  access  to  other  users).  Commands (described below) may be
   entered interactively, on the xauth command line, or in scripts.   Note
   that  this  program  does  not  contact  the  X  server except when the
   generate command is used.  Normally xauth is not  used  to  create  the
   authority  file entry in the first place; the program that starts the X
   server (often xdm or startx) does that.


   The following options may be  used  with  xauth.   They  may  be  given
   individually (e.g., -q -i) or may combined (e.g., -qi).

   -f authfile
           This  option  specifies  the name of the authority file to use.
           By default, xauth will use the file specified by the XAUTHORITY
           environment   variable   or  .Xauthority  in  the  user's  home

   -q      This option indicates that xauth should operate quietly and not
           print  unsolicited  status messages.  This is the default if an
           xauth command is given on the command line or if  the  standard
           output is not directed to a terminal.

   -v      This  option  indicates that xauth should operate verbosely and
           print  status  messages  indicating  the  results  of   various
           operations (e.g., how many records have been read in or written
           out).  This is the default if xauth is  reading  commands  from
           its  standard  input  and  its standard output is directed to a

   -i      This option indicates that xauth should  ignore  any  authority
           file  locks.   Normally,  xauth will refuse to read or edit any
           authority  files  that  have  been  locked  by  other  programs
           (usually xdm or another xauth).

   -b      This  option  indicates  that xauth should attempt to break any
           authority file locks before proceeding.  Use this  option  only
           to clean up stale locks.

   -n      This  option indicates that xauth should not attempt to resolve
           any hostnames, but should simply always print the host  address
           as stored in the authority file.

   -V      This option shows the version number of the xauth executable.


   The following commands may be used to manipulate authority files:

   add displayname protocolname hexkey
           An  authorization  entry  for  the  indicated display using the
           given protocol and key data is added to the authorization file.
           The data is specified as an even-lengthed string of hexadecimal
           digits, each pair representing one octet.  The first  digit  of
           each  pair  gives the most significant 4 bits of the octet, and
           the second digit of the pair  gives  the  least  significant  4
           bits.   For  example,  a  32 character hexkey would represent a
           128-bit value.  A protocol name consisting  of  just  a  single
           period is treated as an abbreviation for MIT-MAGIC-COOKIE-1.

   generate displayname protocolname [trusted|untrusted]
           [timeout seconds] [group group-id] [data hexdata]

           This  command  is  similar to add.  The main difference is that
           instead of requiring the  user  to  supply  the  key  data,  it
           connects  to  the  server specified in displayname and uses the
           SECURITY extension in order to get the key data to store in the
           authorization file.  If the server cannot be contacted or if it
           does not support the SECURITY  extension,  the  command  fails.
           Otherwise,  an  authorization  entry  for the indicated display
           using the given protocol is added to the authorization file.  A
           protocol  name consisting of just a single period is treated as
           an abbreviation for MIT-MAGIC-COOKIE-1.

           If the trusted option is used, clients that connect using  this
           authorization  will have full run of the display, as usual.  If
           untrusted  is   used,   clients   that   connect   using   this
           authorization  will  be considered untrusted and prevented from
           stealing or tampering with data belonging to  trusted  clients.
           See  the  SECURITY  extension specification for full details on
           the restrictions imposed on untrusted clients.  The default  is

           The   timeout   option  specifies  how  long  in  seconds  this
           authorization will be  valid.   If  the  authorization  remains
           unused  (no clients are connected with it) for longer than this
           time period, the server purges the  authorization,  and  future
           attempts  to connect using it will fail.  Note that the purging
           done by the server does not delete the authorization entry from
           the authorization file.  The default timeout is 60 seconds.

           The  group  option specifies the application group that clients
           connecting with this authorization should belong to.   See  the
           application  group  extension  specification  for more details.
           The default is to not belong to an application group.

           The data option specifies data that the server  should  use  to
           generate  the  authorization.   Note  that this is not the same
           data  that  gets  written  to  the  authorization  file.    The
           interpretation  of  this  data  depends  on  the  authorization
           protocol.  The hexdata is in the  same  format  as  the  hexkey
           described in the add command.  The default is to send no data.

   [n]extract filename displayname...
           Authorization  entries  for  each of the specified displays are
           written to the indicated file.   If  the  nextract  command  is
           used,  the entries are written in a numeric format suitable for
           non-binary transmission (such as secure electronic mail).   The
           extracted  entries  can  be  read  back  in using the merge and
           nmerge commands.  If the filename consists  of  just  a  single
           dash, the entries will be written to the standard output.

   [n]list [displayname...]
           Authorization  entries  for  each of the specified displays (or
           all if no displays are  named)  are  printed  on  the  standard
           output.  If the nlist command is used, entries will be shown in
           the numeric format used by  the  nextract  command;  otherwise,
           they  are  shown  in  a  textual  format.   Key  data is always
           displayed in the hexadecimal format given in the description of
           the add command.

   [n]merge [filename...]
           Authorization entries are read from the specified files and are
           merged  into  the  authorization  database,   superseding   any
           matching  existing  entries. If the nmerge command is used, the
           numeric format given in the description of the extract  command
           is  used.   If  a  filename consists of just a single dash, the
           standard input will be read if it hasn't been read before.

   remove displayname...
           Authorization  entries  matching  the  specified  displays  are
           removed from the authority file.

   source filename
           The  specified  file  is  treated  as a script containing xauth
           commands to execute.  Blank lines and lines  beginning  with  a
           sharp  sign  (#)  are  ignored.   A  single dash may be used to
           indicate the standard input, if it hasn't already been read.

   info    Information describing the authorization file, whether  or  not
           any  changes  have been made, and from where xauth commands are
           being read is printed on the standard output.

   exit    If any modifications have been  made,  the  authority  file  is
           written  out  (if  allowed),  and the program exits.  An end of
           file is treated as an implicit exit command.

   quit    The program exits, ignoring any modifications.  This  may  also
           be accomplished by pressing the interrupt character.

   version This command shows the version number of the xauth executable.

   help [string]
           A  description of all commands that begin with the given string
           (or all commands if no string  is  given)  is  printed  on  the
           standard output.

   ?       A  short  list of the valid commands is printed on the standard


   Display names for the add, [n]extract, [n]list,  [n]merge,  and  remove
   commands  use  the  same format as the DISPLAY environment variable and
   the  common   -display   command   line   argument.    Display-specific
   information  (such  as  the  screen  number) is unnecessary and will be
   ignored.  Same-machine connections (such as local-host sockets,  shared
   memory,  and  the Internet Protocol hostname localhost) are referred to
   as hostname/unix:displaynumber so  that  local  entries  for  different
   machines may be stored in one authority file.


   The  most  common use for xauth is to extract the entry for the current
   display, copy it to another machine,  and  merge  it  into  the  user's
   authority file on the remote machine:

           %  xauth extract - $DISPLAY | ssh otherhost xauth merge -

   The following command contacts the server :0 to create an authorization
   using the MIT-MAGIC-COOKIE-1 protocol.  Clients that connect with  this
   authorization will be untrusted.
        %  xauth generate :0 .


   This xauth program uses the following environment variables:

           to  get  the name of the authority file to use if the -f option
           isn't used.

   HOME    to get the user's home directory if XAUTHORITY isn't defined.


           default authority file if XAUTHORITY isn't defined.


   X(7), Xsecurity(7), xhost(1), Xserver(1), xdm(1), startx(1), Xau(3).


   Users that have unsecure networks should take  care  to  use  encrypted
   file   transfer   mechanisms  to  copy  authorization  entries  between
   machines.  Similarly,  the  MIT-MAGIC-COOKIE-1  protocol  is  not  very
   useful   in  unsecure  environments.   Sites  that  are  interested  in
   additional security may need to use encrypted authorization  mechanisms
   such as Kerberos.

   Spaces  are  currently not allowed in the protocol name.  Quoting could
   be added for the truly perverse.


   Jim Fulton, MIT X Consortium


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