1ENDPWENT(P)                POSIX Programmer's Manual               ENDPWENT(P)
2
3
4

NAME

6       endpwent, getpwent, setpwent - user database functions
7

SYNOPSIS

9       #include <pwd.h>
10
11       void endpwent(void);
12       struct passwd *getpwent(void);
13       void setpwent(void);
14
15

DESCRIPTION

17       These functions shall retrieve information about users.
18
19       The  getpwent() function shall return a pointer to a structure contain‐
20       ing the broken-out fields of an entry in the user database. Each  entry
21       in  the  user  database contains a passwd structure. When first called,
22       getpwent() shall return a pointer to a passwd structure containing  the
23       first entry in the user database. Thereafter, it shall return a pointer
24       to a passwd structure containing the next entry in the  user  database.
25       Successive calls can be used to search the entire user database.
26
27       If  an  end-of-file  or  an error is encountered on reading, getpwent()
28       shall return a null pointer.
29
30       An implementation that provides extended security controls  may  impose
31       further implementation-defined restrictions on accessing the user data‐
32       base. In particular, the system may deny the existence of some  or  all
33       of the user database entries associated with users other than the call‐
34       er.
35
36       The setpwent() function effectively rewinds the user database to  allow
37       repeated searches.
38
39       The  endpwent()  function may be called to close the user database when
40       processing is complete.
41
42       These functions need not be reentrant. A function that is not  required
43       to be reentrant is not required to be thread-safe.
44

RETURN VALUE

46       The  getpwent()  function shall return a null pointer on end-of-file or
47       error.
48

ERRORS

50       The getpwent(), setpwent(), and endpwent() functions may fail if:
51
52       EIO    An I/O error has occurred.
53
54
55       In addition, getpwent() and setpwent() may fail if:
56
57       EMFILE {OPEN_MAX} file descriptors are currently open  in  the  calling
58              process.
59
60       ENFILE The  maximum  allowable number of files is currently open in the
61              system.
62
63
64       The return value may point to a static area which is overwritten  by  a
65       subsequent call to getpwuid(), getpwnam(), or getpwent().
66
67       The following sections are informative.
68

EXAMPLES

70   Searching the User Database
71       The  following  example  uses the getpwent() function to get successive
72       entries in the user database, returning a pointer to a passwd structure
73       that  contains  information  about  each  user.  The call to endpwent()
74       closes the user database and cleans up.
75
76
77              #include <pwd.h>
78              ...
79              struct passwd *p;
80              ...
81              while ((p = getpwent ()) != NULL) {
82              ...
83              }
84
85
86              endpwent();
87              ...
88

APPLICATION USAGE

90       These functions are provided due to their  historical  usage.  Applica‐
91       tions  should  avoid  dependencies  on fields in the password database,
92       whether the database is a single file, or where in the file system name
93       space the database resides. Applications should use getpwuid() whenever
94       possible because it avoids these dependencies.
95

RATIONALE

97       None.
98

FUTURE DIRECTIONS

100       None.
101

SEE ALSO

103       endgrent() , getlogin() , getpwnam() , getpwuid() ,  the  Base  Defini‐
104       tions volume of IEEE Std 1003.1-2001, <pwd.h>
105

107       Portions  of  this text are reprinted and reproduced in electronic form
108       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
109       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
110       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
111       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
112       event of any discrepancy between this version and the original IEEE and
113       The  Open Group Standard, the original IEEE and The Open Group Standard
114       is the referee document. The original Standard can be  obtained  online
115       at http://www.opengroup.org/unix/online.html .
116
117
118
119IEEE/The Open Group                  2003                          ENDPWENT(P)
Impressum