GETUSERSHELL(3)                                                         Linux Programmer's Manual                                                        GETUSERSHELL(3)

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)

GNU                                                                            2021-03-22                                                                GETUSERSHELL(3)