Name
getpwnam, getpwnam_r, getpwuid, getpwuid_r — get
password file entry
Synopsis
struct passwd *getpwnam( |
const char * |
name); |
struct passwd *getpwuid( |
uid_t |
uid); |
int
getpwnam_r( |
const char * |
name, |
| |
struct passwd * |
pwbuf, |
| |
char * |
buf, |
| |
size_t |
buflen, |
| |
struct passwd ** |
pwbufp); |
int
getpwuid_r( |
uid_t |
uid, |
| |
struct passwd * |
pwbuf, |
| |
char * |
buf, |
| |
size_t |
buflen, |
| |
struct passwd ** |
pwbufp); |
DESCRIPTION
The getpwnam() function
returns a pointer to a structure containing the broken-out
fields of the record in the password database (e.g., the
local password file /etc/passwd, NIS, and LDAP) that matches
the user name name.
The getpwuid() function
returns a pointer to a structure containing the broken-out
fields of the record in the password database that matches
the user ID uid.
The getpwnam_r() and
getpwuid_r() functions obtain
the same information, but store the retrieved passwd structure in the space
pointed to by pwbuf.
This passwd
structure contains pointers to strings, and these strings are
stored in the buffer buf of size buflen. A pointer to the result
(in case of success) or NULL (in case no entry was found or
an error occurred) is stored in *pwbufp.
The passwd
structure is defined in <pwd.h> as follows:
| struct |
passwd { |
| |
char |
* |
pw_name; |
/* user name */ |
| |
char |
* |
pw_passwd; |
/* user password */ |
| |
uid_t |
|
pw_uid; |
/* user ID */ |
| |
gid_t |
|
pw_gid; |
/* group ID */ |
| |
char |
* |
pw_gecos; |
/* real name */ |
| |
char |
* |
pw_dir; |
/* home directory */ |
| |
char |
* |
pw_shell; |
/* shell program */ |
| }; |
The maximum needed size for buf can be found using sysconf(3) with the
_SC_GETPW_R_SIZE_MAX parameter.
RETURN VALUE
The getpwnam() and
getpwuid() functions return a
pointer to a passwd
structure, or NULL if the matching entry is not found or an
error occurs. If an error occurs, errno is set appropriately. If one wants to
check errno after the call, it
should be set to zero before the call.
The return value may point to static area, and may be
overwritten by subsequent calls to getpwent(3), getpwnam(), or getpwuid().
The getpwnam_r() and
getpwuid_r() functions return
zero on success. In case of error, an error number is
returned.
ERRORS
0 or
ENOENT or ESRCH or EBADF or EPERM or ...-
The given name or uid was not found.
- EINTR
-
A signal was caught.
- EIO
-
I/O error.
- EMFILE
-
The maximum number (OPEN_MAX) of files was open
already in the calling process.
- ENFILE
-
The maximum number of files was open already in the
system.
- ENOMEM
-
Insufficient memory to allocate passwd
structure.
- ERANGE
-
Insufficient buffer space supplied.
FILES
/etc/passwd-
local password database file
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001
NOTES
The formulation given above under "RETURN VALUE" is from
POSIX.1-2001. It does not call "not found" an error, and
hence does not specify what value errno might have in this situation. But that
makes it impossible to recognize errors. One might argue that
according to POSIX errno should
be left unchanged if an entry is not found. Experiments on
various Unix-like systems show that lots of different values
occur in this situation: 0, ENOENT, EBADF, ESRCH,
EWOULDBLOCK, EPERM and probably others.
The pw_dir field
contains the name of the initial working directory of the
user. Login programs use the value of this field to
initialize the HOME environment variable for the login shell.
An application that wants to determine its user's home
directory should inspect the value of HOME (rather than the
value getpwuid(getuid())->pw_dir)
since this allows the user to modify their notion of "the
home directory" during a login session. To determine the
(initial) home directory of another user, it is necessary to
use getpwnam("username")->pw_dir
or similar.
SEE ALSO
endpwent(3), fgetpwent(3), getgrnam(3), getpw(3), getpwent(3), putpwent(3), setpwent(3), passwd(5)
Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.
Since the Linux kernel and libraries are constantly changing, this
manual page may be incorrect or out-of-date. The author(s) assume no
responsibility for errors or omissions, or for damages resulting from
the use of the information contained herein. The author(s) may not
have taken the same level of care in the production of this manual,
which is licensed free of charge, as they might when working
professionally.
Formatted or processed versions of this manual, if unaccompanied by
the source, must acknowledge the copyright and authors of this work.
References consulted:
Linux libc source code
Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
386BSD man pages
Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
Modified 1996-05-27 by Martin Schulze (joey@linux.de)
Modified 2003-11-15 by aeb
|
