NAME

xauth − X authority file utility. 

SYNTAX

xauth [options] [command arguments]

DESCRIPTION

The xauth program is used to edit and display authorization information used when connecting to the X server.  xdm can be configured to generate this authorization information when a user logs on.  xauth is then used to extract authorization records from one machine and merge them in on another (as is the case when using remote logins or to grant access to other users).  Note that this program does not contact the X server. 

For an introduction to user-based access control and the xauth program, see Appendix A, Managing Your Environment. 

OPTIONS

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

-bIndicates that xauth should attempt to break any authority file locks before proceeding and should only be used to clean up stale locks. 

-f authfile
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 directory. 

−iIndicates 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). 

-qIndicates 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. 

-vIndicates 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. 

COMMANDS

Commands may be entered interactively, on the xauth command line, or in scripts.  The following commands may be used to manipulate authority files (or obtain information):

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

add displayname protocolname hexkey
An authorization entry for the indicated displayname using the given protocolname and hexkey data is added to the authorization file.  At present, three protocolnames are supported in the standard X distribution:  MIT-MAGIC-COOKIE-1, XDM-AUTHORIZATION-1, and SUN-DES-1.  Note that xauth will not give you an error if you specify an invalid protocol name.  A protocol name consisting of just a single period is treated as an abbreviation for MIT-MAGIC-COOKIE-1.  The hexkey 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. 

exitIf 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. 

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. 

infoInformation 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. 

[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, 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 hasn’t been read before. 

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

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

source filename
The specified filename is treated as a script containing xauth commands to execute.  In such a file, 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. 

DISPLAY NAMES

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 option.  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. 

EXAMPLE

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 other xauth merge -

ENVIRONMENT VARIABLES

This xauth program uses the following environment variables:

XAUTHORITY
To get the name of the authority file to use if the -f option isn’t used.  If this variable is not set, xauth will use .Xauthority in the user’s home directory. 

HOMETo get the user’s home directory if XAUTHORITY isn’t defined. 

BUGS

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. 

SEE ALSO

X, Xserver, xdm; Appendix A, Managing Your Environment. 

AUTHOR

Jim Fulton, MIT X Consortium.