This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

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

       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.

       Default.

       Thefollowingsectionsareinformative.

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for  Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group                                   2017                                         WRITE(1POSIX)

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

           Messagefromsender-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 POSIX.1‐2017, Chapter11, GeneralTerminalInterface)  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 POSIX.1‐2017, Chapter11, GeneralTerminalInterface.

        *  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 sttyiexten 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 appropriate privileges to perform the requested action.

       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 POSIX.1‐2017, Section8.2, InternationalizationVariables 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.

       None.

       The following exit values shall be returned:

        0    Successful completion.

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

       None.

       None.

       None.

       write — write to another user

       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.

       None.

       The recipient's terminal is used for output.

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

       The write utility was included in this volume of POSIX.1‐2017 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.

mesg, talk, who

       The Base Definitions volume of POSIX.1‐2017,  Chapter8,  EnvironmentVariables,  Chapter11,  GeneralTerminalInterface

       The standard error shall be used only for diagnostic messages.

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

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

       write user_name[terminal]