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U9FS(4) Kernel Interfaces Manual U9FS(4) NAME
u9fs - serve 9P from Unix SYNOPSIS
u9fs [ directory ] DESCRIPTION
U9fs is not a Plan 9 program. Instead it is a program that serves Unix files to Plan 9 machines using the 9P protocol (see intro(5)). It is to be invoked on a Unix machine by inetd with its standard input, output, and error connected to a network connection, typically TCP on an Ethernet. It runs as user root and multiplexes access to multiple Plan 9 clients over the single wire. It simulates Unix permissions itself by assuming Plan 9 uids match Unix login names. If a directory is specified u9fs first does a Unix chroot system call to that directory. Plan 9 calls this service 9fs with TCP service number 564 on the Ethernet. Set up this way on a machine called, say, kremvax, u9fs may be connected to the name space of a Plan 9 process by 9fs kremvax Due to a bug in some versions of the IP software, some systems will not accept the service name 9fs, thinking it a service number because of the initial digit. If so, run the service as u9fs or 564 and do the srv and mount by hand: srv tcp!kremvax!u9fs mount -c /srv/tcp!kremvax!u9fs /n/kremvax For more information on this procedure, see srv(4) and bind(1). U9fs serves the entire file system of the Unix machine. It forbids access to devices because the program is single-threaded and may block unpredictably. Using the attach specifier device connects to a file system identical to the usual system except it permits device access (and may block unpredictably): srv tcp!kremvax!9fs mount -c /srv/tcp!kremvax!9fs /n/kremvax device (The 9fs command does not accept an attach specifier.) Even so, device access may produce unpredictable results if the block size of the device is greater than 8192, the maximum data size of a 9P message. The source to u9fs is in the Plan 9 directory /sys/src/cmd/unix/u9fs. To install u9fs on a Unix system, copy the source to a directory on that system. Edit the makefile to set LOG to a proper place for a log file and to set the compile-time configuration correctly. Then com- pile with an ANSI C compiler and install in /usr/etc/u9fs. Install this line in inetd.conf: 9fs stream tcp nowait root /usr/etc/u9fs u9fs and this in services: 9fs 564/tcp 9fs # Plan 9 fs SOURCE
/sys/src/cmd/unix/u9fs DIAGNOSTICS
Problems are reported to /tmp/u9fs.log. A compile-time flag enables chatty debugging. SEE ALSO
bind(1), srv(4), ip(3), nfsserver(8) BUGS
The implementation of devices is unsatisfactory. U9FS(4)
