CONS(3)                                                   CONS(3)

     NAME
          cons - console device

     SYNOPSIS
          bind #c /dev

          /dev/cons
          /dev/consctl
          /dev/drivers
          /dev/jit
          /dev/keyboard
          /dev/klog
          /dev/kprint
          /dev/memory
          /dev/msec
          /dev/null
          /dev/notquiterandom
          /dev/pgrpid
          /dev/pin
          /dev/pointer
          /dev/random
          /dev/sysname
          /dev/time
          /dev/user

     DESCRIPTION
          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.

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     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 kernel
          logging statements.

          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
          kprint.

          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 an m character followed by three
          integers in the standard Inferno 12-character decimal for-
          mat: right-adjusted numerals with leading blanks to fill the
          field to 11 characters, followed by a blank.  The integers
          are the device's coordinates on the screen and a bit mask
          with the 1, 2, and 4 bits when the pointer's left, middle,
          and right buttons, respectively, are down.

          The pin file, when read, returns either the string no pin if
          no PIN has been set for authentication, or pin set if one
          has.  The pin file may be written once with a decimal repre-
          sentation of the PIN to use on this Inferno machine.

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

     Page 2                       Plan 9             (printed 3/28/24)

     CONS(3)                                                   CONS(3)

          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 sysname file holds the textual name of the machine.

          The user file contains the name of the user associated with
          the current process.

          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 number of
          allocations done, the number of frees done, the number of
          extensions done, 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
          numbers:

          jit  non-zero if `just in time' compilation is configured
               (can be written to change the state).

          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, to set at boot
               time.)

     SOURCE
          /emu/devcon.c
          /os/port/devcons.c

     SEE ALSO
          draw(3), keyboard(6), utf(6)

     BUGS
          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.

     Page 3                       Plan 9             (printed 3/28/24)

     CONS(3)                                                   CONS(3)

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

     Page 4                       Plan 9             (printed 3/28/24)