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  
  This page is part of release 4.15 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/.