man3/getusershell.3

   1 '\" t
   2 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
   3 .\"
   4 .\" SPDX-License-Identifier: Linux-man-pages-copyleft
   5 .\"
   6 .\" References consulted:
   7 .\"     Linux libc source code
   8 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
   9 .\"     386BSD man pages
  10 .\" Modified Sat Jul 24 19:17:53 1993 by Rik Faith (faith@cs.unc.edu)
  11 .TH getusershell 3 (date) "Linux man-pages (unreleased)"
  12 .SH NAME
  13 getusershell, setusershell, endusershell \- get permitted user shells
  14 .SH LIBRARY
  15 Standard C library
  16 .RI ( libc ", " \-lc )
  17 .SH SYNOPSIS
  18 .nf
  19 .B #include <unistd.h>
  20 .PP
  21 .B char *getusershell(void);
  22 .B void setusershell(void);
  23 .B void endusershell(void);
  24 .fi
  25 .PP
  26 .RS -4
  27 Feature Test Macro Requirements for glibc (see
  28 .BR feature_test_macros (7)):
  29 .RE
  30 .PP
  31 .BR getusershell (),
  32 .BR setusershell (),
  33 .BR endusershell ():
  34 .nf
  35     Since glibc 2.21:
  36 .\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
  37         _DEFAULT_SOURCE
  38     In glibc 2.19 and 2.20:
  39         _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
  40     Up to and including glibc 2.19:
  41         _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE < 500)
  42 .fi
  43 .SH DESCRIPTION
  44 The
  45 .BR getusershell ()
  46 function returns the next line from the file
  47 .IR /etc/shells ,
  48 opening the file if necessary.
  49 The line should contain
  50 the pathname of a valid user shell.
  51 If
  52 .I /etc/shells
  53 does not exist or
  54 is unreadable,
  55 .BR getusershell ()
  56 behaves as if
  57 .I /bin/sh
  58 and
  59 .I /bin/csh
  60 were listed in the file.
  61 .PP
  62 The
  63 .BR setusershell ()
  64 function rewinds
  65 .IR /etc/shells .
  66 .PP
  67 The
  68 .BR endusershell ()
  69 function closes
  70 .IR /etc/shells .
  71 .SH RETURN VALUE
  72 The
  73 .BR getusershell ()
  74 function returns NULL on end-of-file.
  75 .SH FILES
  76 .I /etc/shells
  77 .SH ATTRIBUTES
  78 For an explanation of the terms used in this section, see
  79 .BR attributes (7).
  80 .TS
  81 allbox;
  82 lbx lb lb
  83 l l l.
  84 Interface       Attribute       Value
  85 T{
  86 .na
  87 .nh
  88 .BR getusershell (),
  89 .BR setusershell (),
  90 .BR endusershell ()
  91 T}      Thread safety   MT-Unsafe
  92 .TE
  93 .sp 1
  94 .SH STANDARDS
  95 None.
  96 .SH HISTORY
  97 4.3BSD.
  98 .SH SEE ALSO
  99 .BR shells (5)