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     CONS(3)                                                   CONS(3)

          cons - console device

          bind #c /dev


          The console device serves a one-level directory giving
          access to the console and miscellaneous information.

          Reading the cons file returns characters typed on the key-
          board.  Normally, characters are buffered to enable erase
          and kill processing.  A control-U, `^U', typed at the key-
          board kills the current input line (removes all characters
          from the buffer of characters not yet read via cons), and a
          backspace erases the previous non-kill, non-erase character
          from the input buffer.  Killing and erasing only delete
          characters back to, but not including, the last newline.
          Typed keystrokes produce 16-bit characters that are trans-
          lated into the variable-length UTF encoding (see utf(6))
          before putting them into the buffer.  A read of length
          greater than zero causes the process to wait until a newline
          or a `^D' ends the buffer, and then returns as much of the
          buffer as the argument to read allows, but only up to one
          complete line.  A terminating `^D' is not put into the
          buffer.  If part of the line remains, the next read will
          return bytes from that remainder and not part of any new
          line that has been typed since. A single line containing a
          `^D' can be used as an end of file indication to programs
          that take interactive input.

     CONS(3)                                                   CONS(3)

          If the string rawon has been written to the consctl file and
          the file is still open, cons is in raw mode: characters are
          not echoed as they are typed, backspace and `^D' are not
          treated specially, and characters are available to read as
          soon as they are typed.  Ordinary mode is reentered when
          rawoff is written to consctl or this file is closed.

          A write to cons causes the characters to be printed on the
          console screen.

          The keyboard file returns the underlying tokens produced by
          the keyboard hardware as they are produced; in the emulation
          environment, it is like an always-raw cons file.

          The null file throws away anything written to it and always
          returns zero bytes when read.

          The klog file returns the tail of messages written by the
          native kernel debugging function kprint (mainly used when
          debugging interrupt handlers in device drivers).  It is
          available only in native kernel implementations.

          The kprint file returns console output: messages written by
          kernel print statements and messages written by processes to
          this driver's cons file.  Until kprint is opened, system
          console output is handled normally.  Once kprint has been
          opened, if the machine's console is a serial line, the data
          is sent both to the serial console and to kprint; if the
          console is a graphics screen, the data is sent only to

          A read of the pointer file returns the status of the mouse
          or other pointing device: its position and button state.
          The read blocks until the state has changed since the last
          read.  The read returns 49 bytes: the letter m followed by
          four fields containing decimal integers, each 11 characters
          wide followed by a blank.  The integers are: x and y, coor-
          dinates of the pointer on the screen; a bit mask with the 1,
          2, and 4 bits when the pointer's left, middle, and right
          buttons, respectively, are down; and a time stamp in units
          of milliseconds.

          Writing to the pointer file, using the same format, causes
          the pointer to move to the specified x, y position (the but-
          ton and millisecond fields are ignored, and optional).  If
          there is a visible image representing the pointer's posi-
          tion, that will move too.

          The random device returns as many bytes of random data as
          are requested in the read.

          The notquiterandom device returns as many bytes of pseudo-

     CONS(3)                                                   CONS(3)

          random data as are requested in the read; this is typically
          faster than random but the results are more predictable.

          The scancode device provides access to the raw scan codes of
          the primary keyboard . While it is open, key strokes are
          diverted from cons and keyboard . The first read(2) after
          opening returns an identifier string which defines the for-
          mat of data delivered by subsequent reads. Known ones are
          defined in scancode(6). The most common format is a single
          byte per scan code, where the top bit is 1 for up and 0 for
          down, and the bottom 7 bits are the scan code. Some input
          devices have a larger scan code space; in this case scan
          codes are often delivered as two byte little endian quanti-
          ties, where the top bit is the up/down signifier, and the
          bottom 15 bits are the scan code. In all cases the meaning
          of the individual scan codes is device specific.

          The rest of the files contain (mostly) read-only strings.
          Each string has a fixed length: a read (see sys-read(2)) of
          more than that gives a result of that fixed length (the
          result does not include a terminating zero byte); a read of
          less than that length leaves the file offset so the rest of
          the string (but no more) will be read the next time.  To
          reread the file without closing it, seek must be used to
          reset the offset.  When the file contains numeric data, each
          number is formatted in decimal as an 11-digit number with
          leading blanks and one trailing blank: twelve bytes total.

          The sysctl file can be read to return the current Inferno
          version. Writing the string reboot to it attempts to reboot
          the system, writing halt attempts to halt the system. Writ-
          ing nobroken ensures that broken processes have all associ-
          ated memory freed before being destroyed, writing broken
          ensures that they are left in this state to allow debugging
          (the default).  Only the privileged user is allowed to write
          to this file.

          The sysname file holds the textual name of the machine.  It
          can only be written by the privileged user.

          The user file contains the name of the user associated with
          the current process.  It can only be written by the privi-
          leged user. In the emulation environment, writing to this
          file also attempts to set the user id in the host operating
          system to the specified value.

          The memory file returns a formatted presentation of the
          state of the memory allocation pools in the system.  Each
          line of output returned reports, for a single pool, the
          amount of memory in use, the upper size limit, the high
          water mark, the number of allocations done, the number of
          frees done, the number of extensions done, the largest chunk

     CONS(3)                                                   CONS(3)

          available and the name of the pool.

          The drivers file returns a list of the device drivers loaded
          in the system.  Each line gives the name of the device for
          bind(1), such as #c, followed by the name of the driver as
          used in the system configuration file.

          The other files served by the cons device are all single

          jit  non-zero if `just in time' compilation is configured
               (can be written to change the state). Writing 0 turns
               off JIT compilation, 1 turns it on and larger values
               give increasingly detailed traces of the compilation
               for debugging purposes.

          msec the value of a millisecond counter

          time number of microseconds since the epoch 00:00:00 GMT,
               Jan. 1, 1970.  (Can be written once by the privileged
               user, to set at boot time.)


          draw(3), keyboard(6), utf(6), eve(10.2)

          For debugging, on native systems only, two control-T's fol-
          lowed by a letter generate console output: `^T^Tp' prints
          data about kernel processes, `^T^Ts' prints the kernel
          stack, `^T^Tx' prints data about memory allocation.

          The system can be rebooted by typing `^T^Tr'.