BIND(1)BIND(1)NAME
bind, mount, unmount - change name space
SYNOPSISbind [ option ... ] source target
mount [ option ... ] source target [ spec ]
unmount [ source ] target
DESCRIPTION
The bind and mount commands modify the file name space of the current
process and other processes in the same name space group (see sys-
pctl(2)). For both calls, target is the name of an existing file or
directory in the current name space where the modification is to be
made.
For bind, source is the name of an existing file or directory in the
current name space. After a successful bind, the file name target is
an alias for the object originally named by source; if the modification
doesn't hide it, source will also still refer to its original file.
The evaluation of source (see sys-intro(2)) happens at the time of the
bind, not when the binding is later used.
Both source and target files must be of the same type: either both
directories or both files.
For mount, source can be a shell command, a network address, or a file
name. If source is surrounded by brace characters ({ and }), it is
invoked as a sh(1) command and its standard input is mounted (no
authentication takes place in this case). If source contains an excla‐
mation mark (!), or there is no file of that name, it is assumed to be
a network address for a machine acting as a file server. This argument
should then conform to the conventions described in dial(2). Otherwise
source should be the name of a file that when opened gives a connection
to a file server, something serving the 9P protocol described in
intro(5), formerly called `Styx'. The optional spec argument to mount
is passed in the attach(5) message and selects amongst different file
trees offered by the server.
The effects of bind and mount can be undone by unmount. If two argu‐
ments are given to unmount, the effect is to undo a bind or mount with
the same arguments. If only one argument is given, everything bound to
or mounted on target is unmounted.
By default, bind and mount replace the target file by the new one,
source. Henceforth, an evaluation of the pathname target will be
translated to the new file. If they are directories (for mount, this
condition is true by definition), target becomes a union directory con‐
sisting of one directory (the source directory).
A union directory unites the contents of the source and target directo‐
ries. If the same name appears in both directories, the name used is
the one in the directory that is bound before the other. In particu‐
lar, if the directories have subdirectories of the same name, only the
contents of the subdirectory in the top directory will be seen. If the
subdirectory contents are themselves to be united, that must be done
first in a separate bind or mount.
Note that the # character in the name of a kernel device must be quoted
when used in a bind or unmount command, or the shell will take it as
the start of a comment.
Options control aspects of the modification to the name space:
-b Both files must be directories. Add the source directory to the
beginning of the union directory represented by the target
directory.
-a Both files must be directories. Add the source directory to the
end of the union directory represented by the target directory.
-c This can be used in addition to any of the above to permit cre‐
ation in a union directory. When a new file is created in a
union directory, it is placed in the first element of the union
that has been bound or mounted with the -c option. If that
directory has not got write permission, the create fails.
-q Exit quietly without printing a diagnostic if the bind or mount
fails.
-A For mount only. Do not authenticate the connection to the server
before proceeding with mount. Otherwise the connection is
authenticated by security-auth(2).
-C alg For mount only, specify the algorithm, alg, to be used following
authentication for digesting or encryption. See ssl(3) for the
supported algorithms. The default is none: ssl(3) is not used
after authentication.
-k kfile
For mount only, specify the keyfile to be used when authenticat‐
ing. The default is /usr/user/keyring/default. See keyring-
auth(2) for more details. (If the -9 option is given, this
option is interpreted differently: see below.)
-9 For mount only, and only when hosted on Plan 9. Source is a
Plan 9 file server; use Plan 9's factotum as authentication
agent to authenticate the mount. (Note that a Plan 9 file ser‐
vice that is known not to authenticate can be mounted from any
Inferno host, by using the -A option to suppress Inferno authen‐
tication.) The existing Plan 9 file servers do not encrypt con‐
nections, so the -C option is ignored. The value of the -k
option is added to the key specification for factotum(4) for
authentication.
-P When source is a network address, use styxpersist(2) to try to
simulate a permanent connection, even should the server reboot.
Note the caveats on that page.
-o For mount only, the file server serves the 1995 version of
Inferno's Styx protocol, and mount inserts a process that trans‐
lates to the current version.
SOURCE
/appl/cmd/bind.b
/appl/cmd/mount.b
/appl/cmd/unmount.b
SEE ALSOsh(1), dial(2), keyring-auth(2), security-auth(2), sys-intro(2), sys-
bind(2), intro(3), getauthinfo(8)BIND(1)
