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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 |
TALK(1P) POSIX Programmer's Manual TALK(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.
talk — talk to another user
talk address [terminal]
The talk utility is a two-way, screen-oriented communication program.
When first invoked, talk shall send a message similar to:
Message from <unspecified string>
talk: connection requested by your_address
talk: respond with: talk your_address
to the specified address. At this point, the recipient of the
message can reply by typing:
talk your_address
Once communication is established, the two parties can type
simultaneously, with their output displayed in separate regions of
the screen. Characters shall be processed as follows:
* Typing the <alert> character shall alert the recipient's
terminal.
* Typing <control>‐L shall cause the sender's screen regions to be
refreshed.
* 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 terminate
the local talk utility. Once the talk session has been terminated
on one side, the other side of the talk session shall be notified
that the talk session has been terminated and shall be able to do
nothing except 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 shall be implementation-
defined.
* Typing other non-printable characters shall cause implementation-
defined sequences of printable characters to be sent to the
recipient's terminal.
Permission to be a recipient of a talk 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 talk utility shall fail when the user lacks
appropriate privileges to perform the requested action.
Certain block-mode terminals do not have all the capabilities
necessary to support the simultaneous exchange of messages required
for talk. When this type of exchange cannot be supported on such
terminals, the implementation may support an exchange with reduced
levels of simultaneous interaction or it may report an error
describing the terminal-related deficiency.
None.
The following operands shall be supported:
address The recipient of the talk session. One form of address is
the <user name>, as returned by the who utility. Other
address formats and how they are handled are unspecified.
terminal If the recipient is logged in more than once, the terminal
argument can be used to indicate the appropriate terminal
name. If terminal is not specified, the talk message shall
be displayed on one or more accessible terminals in use by
the recipient. The format of terminal shall be the same as
that returned by the who utility.
Characters read from standard input shall be copied to the
recipient's terminal in an unspecified manner. If standard input is
not a terminal, talk shall write a diagnostic message and exit with a
non-zero status.
None.
The following environment variables shall affect the execution of
talk:
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.
TERM Determine the name of the invoker's terminal type. If this
variable is unset or null, an unspecified default terminal
type shall be used.
When the talk utility receives a SIGINT signal, the utility shall
terminate and exit with a zero status. It shall take the standard
action for all other signals.
If standard output is a terminal, characters copied from the
recipient's standard input may be written to standard output.
Standard output also may be used for diagnostic messages. If standard
output is not a terminal, talk shall exit with a non-zero status.
None.
None.
None.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred or talk was invoked on a terminal incapable
of supporting it.
Default.
The following sections are informative.
Because the handling of non-printable, non-<space> characters is tied
to the stty description of iexten, implementation extensions within
the terminal driver can be accessed. For example, some
implementations provide line editing functions with certain control
character sequences.
None.
The write utility was included in this volume of POSIX.1‐2008 since
it can be implemented on all terminal types. The talk utility, which
cannot be implemented on certain terminals, was considered to be a
``better'' communications interface. Both of these programs are in
widespread use on historical implementations. Therefore, both
utilities have been specified.
All references to networking abilities (talking to a user on another
system) were removed as being outside the scope of this volume of
POSIX.1‐2008.
Historical BSD and System V versions of talk terminate both of the
conversations when either user breaks out of the session. This can
lead to adverse consequences if a user unwittingly continues to enter
text that is interpreted by the shell when the other terminates the
session. Therefore, the version of talk specified by this volume of
POSIX.1‐2008 requires both users to terminate their end of the
session explicitly.
Only messages sent to the terminal of the invoking user can be
internationalized in any way:
* The original ``Message from <unspecified string> ...'' message
sent to the terminal of the recipient cannot be internationalized
because the environment of the recipient is as yet inaccessible
to the talk utility. The environment of the invoking party is
irrelevant.
* Subsequent communication between the two parties cannot be
internationalized because the two parties may specify different
languages in their environment (and non-portable characters
cannot be mapped from one language to another).
* Neither party can be required to communicate in a language other
than C and/or the one specified by their environment because
unavailable terminal hardware support (for example, fonts) may be
required.
The text in the STDOUT section reflects the usage of the verb
``display'' in this section; some talk implementations actually use
standard output to write to the terminal, but this volume of
POSIX.1‐2008 does not require that to be the case.
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.
The handling of non-printable characters is partially implementation-
defined because the details of mapping them to printable sequences is
not needed by the user. Historical implementations, for security
reasons, disallow the transmission of non-printable characters that
may send commands to the other terminal.
None.
mesg(1p), stty(1p), who(1p), write(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 TALK(1P)
Pages that refer to this page: mesg(1p), write(1p)