talk(1p) — Linux manual page


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

       talk — talk to another user

SYNOPSIS         top

       talk address [terminal]

DESCRIPTION         top

       The talk utility is a two-way, screen-oriented communication

       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

        *  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.1‐2017,
           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

        *  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.

OPTIONS         top


OPERANDS         top

       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

       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.

STDIN         top

       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.

INPUT FILES         top



       The following environment variables shall affect the execution of

       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.

                 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.

STDOUT         top

       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.

STDERR         top


OUTPUT FILES         top




EXIT STATUS         top

       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.



       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.

EXAMPLES         top


RATIONALE         top

       The write utility was included in this volume of POSIX.1‐2017
       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.1‐2017.

       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.1‐2017 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.1‐2017 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



SEE ALSO         top

       mesg(1p), stty(1p), who(1p), write(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 .

       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 .

IEEE/The Open Group               2017                          TALK(1P)

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