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NAME

       write - write to another user

SYNOPSIS

       write user_name [terminal]

DESCRIPTION

       The  write  utility shall read lines from the user’s standard input and
       write them to the terminal of another  user.  When  first  invoked,  it
       shall write the message:

              Message from sender-login-id (sending-terminal) [date]...

       to  user_name.  When  it has successfully completed the connection, the
       sender’s terminal shall be alerted twice  to  indicate  that  what  the
       sender is typing is being written to the recipient’s terminal.

       If the recipient wants to reply, this can be accomplished by typing:

              write sender-login-id [sending-terminal]

       upon  receipt  of  the  initial  message.  Whenever  a line of input as
       delimited by an NL,  EOF,  or  EOL  special  character  (see  the  Base
       Definitions   volume   of  IEEE Std 1003.1-2001,  Chapter  11,  General
       Terminal Interface) is accumulated while in canonical input  mode,  the
       accumulated  data  shall  be  written  on  the  other  user’s terminal.
       Characters shall be processed as follows:

        * Typing <alert> shall write the alert character  to  the  recipient’s
          terminal.

        * Typing  the  erase  and  kill  characters  shall affect the sender’s
          terminal in the manner described by the  termios  interface  in  the
          Base Definitions volume of IEEE Std 1003.1-2001, Chapter 11, General
          Terminal Interface.

        * Typing the interrupt or end-of-file characters shall cause write  to
          write  an  appropriate message ( "EOT\n" in the POSIX locale) to the
          recipient’s terminal and exit.

        * Typing characters from LC_CTYPE classifications print or space shall
          cause those characters to be sent to the recipient’s terminal.

        * When  and  only  when  the  stty  iexten  local mode is enabled, the
          existence and processing of additional  special  control  characters
          and multi-byte or single-byte functions is implementation-defined.

        * Typing  other  non-printable  characters shall cause implementation-
          defined sequences of printable  characters  to  be  written  to  the
          recipient’s terminal.

       To  write  to  a  user  who  is  logged in more than once, the terminal
       argument can be used to indicate which terminal to write to; otherwise,
       the  recipient’s  terminal  is  selected  in  an implementation-defined
       manner and an informational message is written to the sender’s standard
       output, indicating which terminal was chosen.

       Permission  to  be  a  recipient  of  a  write message can be denied or
       granted by use of the mesg utility. However,  a  user’s  privilege  may
       further   constrain   the  domain  of  accessibility  of  other  users’
       terminals. The write  utility  shall  fail  when  the  user  lacks  the
       appropriate privileges to perform the requested action.

OPTIONS

       None.

OPERANDS

       The following operands shall be supported:

       user_name
              Login  name  of the person to whom the message shall be written.
              The application shall ensure that this operand is  of  the  form
              returned by the who utility.

       terminal
              Terminal  identification  in the same format provided by the who
              utility.

STDIN

       Lines to be copied to the recipient’s terminal are read  from  standard
       input.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       The  following  environment  variables  shall  affect  the execution of
       write:

       LANG   Provide a default value for the  internationalization  variables
              that  are  unset  or  null.  (See the Base Definitions volume of
              IEEE Std 1003.1-2001,    Section    8.2,    Internationalization
              Variables  for  the precedence of internationalization variables
              used to determine the values of locale categories.)

       LC_ALL If set to a non-empty string value, override the values  of  all
              the other internationalization variables.

       LC_CTYPE
              Determine  the  locale  for  the  interpretation of sequences of
              bytes of text data as characters (for  example,  single-byte  as
              opposed  to multi-byte characters in arguments and input files).
              If the recipient’s locale does not use an LC_CTYPE equivalent to
              the sender’s, the results are undefined.

       LC_MESSAGES
              Determine  the  locale  that should be used to affect the format
              and contents of diagnostic messages written  to  standard  error
              and informative messages written to standard output.

       NLSPATH
              Determine the location of message catalogs for the processing of
              LC_MESSAGES .

ASYNCHRONOUS EVENTS

       If an interrupt signal is received, write shall  write  an  appropriate
       message  on the recipient’s terminal and exit with a status of zero. It
       shall take the standard action for all other signals.

STDOUT

       An informational message shall be  written  to  standard  output  if  a
       recipient is logged in more than once.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       The recipient’s terminal is used for output.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The following exit values shall be returned:

        0     Successful completion.

       >0     The addressed user is not logged on or the addressed user denies
              permission.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       The talk utility is considered by  some  users  to  be  a  more  usable
       utility on full-screen terminals.

EXAMPLES

       None.

RATIONALE

       The  write  utility was included in this volume of IEEE Std 1003.1-2001
       since it can  be  implemented  on  all  terminal  types.  The  standard
       developers  considered the talk utility, which cannot be implemented on
       certain terminals, to be a "better" communications interface.  Both  of
       these  programs  are  in  widespread use on historical implementations.
       Therefore, the standard developers decided that both  utilities  should
       be specified.

       The format of the terminal name is unspecified, but the descriptions of
       ps, talk, who, and write require that they all use or accept  the  same
       format.

FUTURE DIRECTIONS

       None.

SEE ALSO

       mesg    ,   talk   ,   who   ,   the   Base   Definitions   volume   of
       IEEE Std 1003.1-2001, Chapter 11, General Terminal Interface

COPYRIGHT

       Portions of this text are reprinted and reproduced in  electronic  form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
       event of any discrepancy between this version and the original IEEE and
       The Open Group Standard, the original IEEE and The Open Group  Standard
       is  the  referee document. The original Standard can be obtained online
       at http://www.opengroup.org/unix/online.html .