write(1p) — Linux manual page

PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

WRITE(1P)               POSIX Programmer's Manual              WRITE(1P)

PROLOG         top

       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         top

       write — write to another user

SYNOPSIS         top

       write user_name [terminal]

DESCRIPTION         top

       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.1‐2017, 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.1‐2017,
           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         top

       None.

OPERANDS         top

       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         top

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

INPUT FILES         top

       None.

ENVIRONMENT VARIABLES         top

       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, 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         top

       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         top

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

STDERR         top

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES         top

       The recipient's terminal is used for output.

EXTENDED DESCRIPTION         top

       None.

EXIT STATUS         top

       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         top

       Default.

       The following sections are informative.

APPLICATION USAGE         top

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

EXAMPLES         top

       None.

RATIONALE         top

       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.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       mesg(1p), talk(1p), who(1p)

       The Base Definitions volume of POSIX.1‐2017, Chapter 8,
       Environment Variables, Chapter 11, General Terminal Interface

COPYRIGHT         top

       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(1P)

Pages that refer to this page: logger(1p)mesg(1p)talk(1p)