man(1) Manual page archive

     BIND(1)                                                   BIND(1)

          bind, mount, unmount - change name space

          bind [ option ... ] source target

          mount [ option ... ] source target [ spec ]

          unmount [ source ] target

          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 direc-
          tory 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 exclamation 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 argu-
          ment should then conform to the conventions described in
          sys-dial(2). Otherwise source should be the name of a file
          that when opened gives a connection to a file server, some-
          thing serving the Styx protocol described in intro(5). 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 arguments 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

          By default, bind and mount replace the target file by the

     BIND(1)                                                   BIND(1)

          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 defini-
          tion), target becomes a union directory consisting of one
          directory (the source directory).

          A union directory unites the contents of the source and tar-
          get directories.  If the same name appears in both directo-
          ries, the name used is the one in the directory that is
          bound before the other.  In particular, 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

          -b   Both files must be directories.  Add the source direc-
               tory to the beginning of the union directory repre-
               sented by the target directory.

          -a   Both files must be directories.  Add the  source direc-
               tory 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 creation 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

     BIND(1)                                                   BIND(1)

               authenticating.  The default is
               /usr/user/keyring/default.  See keyring-auth(2) for
               more details.

          -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 service that is known not to authen-
               ticate can be mounted from any Inferno host, by using
               the -A option to suppress Inferno authentication.)  The
               existing Plan 9 file servers do not encrypt connec-
               tions, so the -C and -k options are ignored.

          -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 original
               version of the Styx protocol, and mount inserts a pro-
               cess that translates to the current version.


          sh(1), keyring-auth(2), security-auth(2), sys-intro(2),
          sys-bind(2), sys-dial(2), intro(3), getauthinfo(8)