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WRITE(1P) POSIX Programmer's Manual WRITE(1P)
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.
write — write to another user
write user_name [terminal]
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.
None.
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.
Lines to be copied to the recipient's terminal are read from standard
input.
None.
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.
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.
An informational message shall be written to standard output if a
recipient is logged in more than once.
The standard error shall be used only for diagnostic messages.
The recipient's terminal is used for output.
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.
Default.
The following sections are informative.
The talk utility is considered by some users to be a more usable
utility on full-screen terminals.
None.
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.
None.
mesg(1p), talk(1p), who(1p)
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 .
IEEE/The Open Group 2013 WRITE(1P)
Pages that refer to this page: logger(1p), mesg(1p), talk(1p)