xenial (1) write.1posix.gz

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PROLOG

       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.

NAME

       write — write to another user

SYNOPSIS

       write user_name [terminal]

DESCRIPTION

       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:

           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 POSIX.1‐2008, 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 POSIX.1‐2008, 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 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 POSIX.1‐2008, 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 POSIX.1‐2008 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 POSIX.1‐2008,  Chapter  8,  Environment  Variables,  Chapter  11,  General
       Terminal Interface

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition,
       Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open  Group  Base
       Specifications  Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc
       and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/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 .