getusershell(3)		    Library Functions Manual		 getusershell(3)

NAME
     getusershell, setusershell, endusershell - get permitted user shells

LIBRARY
     Standard C library (libc, -lc)

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 un-
     readable, 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).
     allbox; lbx lb lb l l l.  Interface Attribute Value T{ getusershell(),
     setusershell(), endusershell() T}	 Thread safety	MT-Unsafe

STANDARDS
     None.

HISTORY
     4.3BSD.

SEE ALSO
     shells(5)

Linux man-pages 6.18		   2026-02-08			 getusershell(3)