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     STAT(5)                                                   STAT(5)

     NAME
          stat, wstat - inquire or change file attributes

     SYNOPSIS
          Tstat   tag[2] fid[2]
          Rstat   tag[2] fid[2] stat[116]

          Twstat  tag[2] fid[2] stat[116]
          Rwstat  tag[2] fid[2]

     DESCRIPTION
          The stat transaction inquires about the file identified by
          fid. The reply will contain a 116-byte (DIRLEN in <libc.h>)
          machine-independent directory entry laid out as follows:

          name[28]       file name; must be / if the file is the root
                         directory of the server
          uid[28]        owner name
          gid[28]        group name
          qid.path[4]    the file server's identification for the file
          qid.vers[4]    version number for given path
          mode[4]        permissions and flags
          atime[4]       last access time
          mtime[4]       last modification time
          length[8]      length of file in bytes
          type[2]        for kernel use
          dev[2]         for kernel use

          Integers in this encoding are in little-endian order (least
          significant byte first).  The convM2D and convD2M routines
          (see fcall(2)) convert between directory entries and C
          structs.

          This encoding may be turned into a machine dependent Dir
          structure (see stat(2)) using routines defined in fcall(2).

          The mode contains permission bits as described in intro(5)
          and the following: 0x80000000 (this file is a directory),
          0x40000000 (append only), 0x20000000 (exclusive use).
          Writes to append-only files always place their data at the
          end of the file; the offset in the read or write message is
          ignored, as is the OTRUNC bit in an open.  Exclusive use
          files may be open for I/O by only one fid at a time across
          all clients of the server.  If a second open is attempted,
          it draws an error.  Servers may implement a timeout on the
          lock on an exclusive use file: if the fid holding the file
          open has been unused for an extended period (of order at
          least minutes), it is reasonable to break the lock and deny
          the initial fid further I/O.

     STAT(5)                                                   STAT(5)

          The two time fields are measured in seconds since the epoch
          (Jan 1 00:00 1970 GMT).  The mtime field reflects the time
          of the last change of content.  For a plain file, mtime is
          the time of the most recent create, open with truncation, or
          write; for a directory it is the time of the most recent
          remove, create, or wstat of a file in the directory.  Simi-
          larly, the atime field records the last read of the con-
          tents; also it is set whenever mtime is set.  In addition,
          for a directory, it is set by an attach, walk, or create,
          all whether successful or not.

          The length records the number of bytes in the file.  Direc-
          tories and most files representing devices have a conven-
          tional length of 0.

          The stat request requires no special permissions.

          The wstat request can change some of the file status infor-
          mation.  The name can be changed by anyone with write per-
          mission in the parent directory; it is an error to change
          the name to that of an existing file.  The mode and mtime
          can be changed by the owner of the file or the group leader
          of the file's current group.  The directory bit cannot be
          changed by a wstat; the other defined permission and mode
          bits can.  The gid can be changed: by the owner if also a
          member of the new group; or by the group leader of the
          file's current group if also leader of the new group (see
          intro(5) for more information about permissions and users(6)
          for users and groups).  None of the other data can be
          altered by a wstat.  In particular, there is no way to
          change the owner of a file.

          A read of a directory yields an integral number of directory
          entries in the machine independent encoding given above (see
          read(5)).

     ENTRY POINTS
          Stat messages are generated by fstat and stat.

          Wstat messages are generated by fwstat and wstat.