ENDPWENT(3P) POSIX Programmer's Manual ENDPWENT(3P)
PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the correspond-
ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME
endpwent, getpwent, setpwent - user database functions
SYNOPSIS
#include <pwd.h>
void endpwent(void);
struct passwd *getpwent(void);
void setpwent(void);
DESCRIPTION
These functions shall retrieve information about users.
The getpwent() function shall return a pointer to a structure containing the broken-out fields of an entry in the user database. Each entry
in the user database contains a passwd structure. When first called, getpwent() shall return a pointer to a passwd structure containing the
first entry in the user database. Thereafter, it shall return a pointer to a passwd structure containing the next entry in the user data-
base. Successive calls can be used to search the entire user database.
If an end-of-file or an error is encountered on reading, getpwent() shall return a null pointer.
An implementation that provides extended security controls may impose further implementation-defined restrictions on accessing the user
database. In particular, the system may deny the existence of some or all of the user database entries associated with users other than the
caller.
The setpwent() function effectively rewinds the user database to allow repeated searches.
The endpwent() function may be called to close the user database when processing is complete.
These functions need not be reentrant. A function that is not required to be reentrant is not required to be thread-safe.
RETURN VALUE
The getpwent() function shall return a null pointer on end-of-file or error.
ERRORS
The getpwent(), setpwent(), and endpwent() functions may fail if:
EIO An I/O error has occurred.
In addition, getpwent() and setpwent() may fail if:
EMFILE {OPEN_MAX} file descriptors are currently open in the calling process.
ENFILE The maximum allowable number of files is currently open in the system.
The return value may point to a static area which is overwritten by a subsequent call to getpwuid(), getpwnam(), or getpwent().
The following sections are informative.
EXAMPLES
Searching the User Database
The following example uses the getpwent() function to get successive entries in the user database, returning a pointer to a passwd struc-
ture that contains information about each user. The call to endpwent() closes the user database and cleans up.
#include <pwd.h>
...
struct passwd *p;
...
while ((p = getpwent ()) != NULL) {
...
}
endpwent();
...
APPLICATION USAGE
These functions are provided due to their historical usage. Applications should avoid dependencies on fields in the password database,
whether the database is a single file, or where in the file system name space the database resides. Applications should use getpwuid()
whenever possible because it avoids these dependencies.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
endgrent(), getlogin(), getpwnam(), getpwuid(), the Base Definitions volume of IEEE Std 1003.1-2001, <pwd.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
ogy -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE
and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained
online at http://www.opengroup.org/unix/online.html .
IEEE
/The Open Group 2003 ENDPWENT(3P)