READ(5) 							File Formats Manual							   READ(5)

NAME

       read, write - transfer data from and to a file

SYNOPSIS

       Tread   tag[2] fid[2] offset[8] count[2]
       Rread   tag[2] fid[2] count[2] pad[1] data[count]

       Twrite  tag[2] fid[2] offset[8] count[2] pad[1] data[count]
       Rwrite  tag[2] fid[2] count[2]

DESCRIPTION

       The  read  request  asks  for  count bytes of data from the file identified by fid, which must be opened for reading, starting offset bytes
       after the beginning of the file.  Count must be less than or equal to MAXFDATA (8192, defined in <fcall.h>).  The bytes are  returned  with
       the read reply message.

       The  count  field in the reply indicates the number of bytes returned.  This may be less than the requested amount.  If the offset field is
       greater than the number of bytes in the file, a count of zero will be returned.	For directories, read returns an integral number of direc-
       tory  entries  exactly as in stat (see stat(5)), one for each member of the directory.  The read request message must have offset and count
       zero modulo DIRLEN.

       The write request asks that count bytes of data be recorded in the file identified by fid, which must be opened for writing, starting  off-
       set bytes after the beginning of the file.  If the file has been opened append only, the data will be placed at the end of the file regard-
       less of offset.	Directories may not be written.

       The write reply records the number of bytes actually written.  It is usually an error if this is not the same as requested.

ENTRY POINTS

       Read and write messages are generated by the corresponding calls.  Because of the MAXFDATA limit, more than one message may be produced	by
       a single call.

																	   READ(5)