NAME

       getusershell, setusershell, endusershell - get permitted user shells

SYNOPSIS

       #include <unistd.h>

       char *getusershell(void);
       void setusershell(void);
       void endusershell(void);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       getusershell(), setusershell(), endusershell():
           Since glibc 2.21:
               _DEFAULT_SOURCE
           In glibc 2.19 and 2.20:
               _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
           Up to and including glibc 2.19:
               _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)

DESCRIPTION

       The  getusershell()  function returns the next line from the file /etc/shells, opening the
       file if necessary.  The line should contain the  pathname  of  a  valid  user  shell.   If
       /etc/shells  does  not  exist  or  is unreadable, getusershell() behaves as if /bin/sh and
       /bin/csh were listed in the file.

       The setusershell() function rewinds /etc/shells.

       The endusershell() function closes /etc/shells.

RETURN VALUE

       The getusershell() function returns NULL on end-of-file.

FILES

       /etc/shells

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌─────────────────────────────────────────────────────────────┬───────────────┬───────────┐
       │Interface                                                    │ Attribute     │ Value     │
       ├─────────────────────────────────────────────────────────────┼───────────────┼───────────┤
       │getusershell(), setusershell(), endusershell()               │ Thread safety │ MT-Unsafe │
       └─────────────────────────────────────────────────────────────┴───────────────┴───────────┘

CONFORMING TO

       4.3BSD.

SEE ALSO

       shells(5)

COLOPHON

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       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.