This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface

       None.

       Default.

       Default.

       Thefollowingsectionsareinformative.

       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                                         UNSET(1POSIX)

       Each variable or function specified by name shall be unset.

       If  -v  is  specified, name refers to a variable name and the shell shall unset it and remove it from the
       environment. Read-only variables cannot be unset.

       If -f is specified, name refers to a function and the shell shall unset the function definition.

       If neither -f nor -v is specified, name refers to a variable; if a variable by that name does not  exist,
       it is unspecified whether a function by that name, if any, shall be unset.

       Unsetting  a  variable  or function that was not previously set shall not be considered an error and does
       not cause the shell to abort.

       The unset special built-in shall support the Base  Definitions  volume  of  POSIX.1‐2017,  Section12.2,
       UtilitySyntaxGuidelines.

       Note that:

           VARIABLE=

       is  not  equivalent  to an unset of VARIABLE; in the example, VARIABLE is set to "".  Also, the variables
       that can be unset should not be misinterpreted to include the  special  parameters  (see  Section2.5.2,
       SpecialParameters).

       None.

       Unset VISUAL variable:

           unset -v VISUAL

       Unset the functions foo and bar:

           unset -f foo bar

        0    All name operands were successfully unset.

       >0    At least one name could not be unset.

       None.

       None.

       None.

       unset — unset values and attributes of variables and functions

       See the DESCRIPTION.

       See the DESCRIPTION.

       None.

       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.

       Consideration  was  given  to  omitting the -f option in favor of an unfunction utility, but the standard
       developers decided to retain historical practice.

       The -v option was introduced because System V historically used one name space  for  both  variables  and
       functions.  When  unset  is  used  without  options,  System  V historically unset either a function or a
       variable, and there was no confusion about which one was intended.  A portable POSIX application can  use
       unset without an option to unset a variable, but not a function; the -f option must be used.

Section2.14, SpecialBuilt-InUtilities

       The Base Definitions volume of POSIX.1‐2017, Section12.2, UtilitySyntaxGuidelines

       The standard error shall be used only for diagnostic messages.

       Not used.

       Not used.

       unset [-fv]name...