xauth - X authority file utility
xauth [-f authfile] [-vqib] [commandarg...]
The following options may be used with xauth. They may be
given individually (for example, -q -i) or may combined
(for example, -qi). 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
in the user's home directory. 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. This option indicates that
xauth should operate verbosely and print status messages
indicating the results of various operations (for example,
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 terminal.
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). This option
indicates that xauth should attempt to break any authority
file locks before proceeding. Use this option only to
clean up stale locks.
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. Normally
xauth is not used to create the authority file entry
in the first place; xdm does that.
The following commands may be used to manipulate authority
files: 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 evenlengthed
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.
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. 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.
Authorization entries are read from the specified
files and are merged into the authorization database,
superceding 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 has not been read before. Authorization
entries matching the specified displays are removed from
the authority file. 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 has not already been read. 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. 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. The program exits, ignoring any
modifications. This may also be accomplished by pressing
the interrupt character. 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
output.
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. Samemachine
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 | rsh otherhost xauth
merge -
This xauth program uses the following environment variables:
to get the name of the authority file to use if the
-f option is not used. to get the user's home directory
if XAUTHORITY is not defined.
default authority file if XAUTHORITY is not defined.
Users that have unsecure networks should take care to use
encrypted file transfer mechanisms to copy authorization
entries between machines. Similarly, the MIT-MAGICCOOKIE-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
xauth(1X)
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