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(), │ Thread safety │ MT-Unsafe │
       │endusershell()                  │               │           │
       └────────────────────────────────┴───────────────┴───────────┘

CONFORMING TO

       4.3BSD.

SEE ALSO

       shells(5)

COLOPHON

       This page is part of release 5.05 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.