Ubuntu Manpage: write - write to another user

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.

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 .