mirror of https://github.com/mkerrisk/man-pages
236 lines
6.2 KiB
Groff
236 lines
6.2 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's "POSIX Programmer's Guide" (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\"
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.\" Modified 1993-07-24 by Rik Faith (faith@cs.unc.edu)
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.\" Modified 1996-05-27 by Martin Schulze (joey@linux.de)
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.\" Modified 2003-11-15 by aeb
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.\"
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.TH GETPWNAM 3 2007-07-26 "GNU" "Linux Programmer's Manual"
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.SH NAME
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getpwnam, getpwnam_r, getpwuid, getpwuid_r \- get password file entry
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.SH SYNOPSIS
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.nf
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.B #include <sys/types.h>
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.B #include <pwd.h>
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.sp
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.BI "struct passwd *getpwnam(const char *" name );
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.sp
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.BI "struct passwd *getpwuid(uid_t " uid );
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.sp
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.BI "int getpwnam_r(const char *" name ", struct passwd *" pwbuf ,
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.br
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.BI " char *" buf ", size_t " buflen ", struct passwd **" pwbufp );
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.sp
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.BI "int getpwuid_r(uid_t " uid ", struct passwd *" pwbuf ,
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.br
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.BI " char *" buf ", size_t " buflen ", struct passwd **" pwbufp );
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.fi
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.sp
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.in -4n
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Feature Test Macro Requirements for glibc (see
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.BR feature_test_macros (7)):
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.in
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.sp
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.ad l
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.BR getpwnam_r (),
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.BR getpwuid_r ():
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_POSIX_C_SOURCE || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE
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.ad b
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.SH DESCRIPTION
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The
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.BR getpwnam ()
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function returns a pointer to a structure containing
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the broken-out fields of the record in the password database
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(e.g., the local password file
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.IR /etc/passwd ,
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NIS, and LDAP)
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that matches the username
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.IR name .
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.PP
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The
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.BR getpwuid ()
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function returns a pointer to a structure containing
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the broken-out fields of the record in the password database
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that matches the user ID
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.IR uid .
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.PP
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The
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.BR getpwnam_r ()
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and
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.BR getpwuid_r ()
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functions obtain the same information, but store the retrieved
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.I passwd
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structure in the space pointed to by
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.IR pwbuf .
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This
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.I passwd
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structure contains pointers to strings, and these strings
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are stored in the buffer
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.I buf
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of size
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.IR buflen .
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A pointer to the result (in case of success) or NULL (in case no entry
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was found or an error occurred) is stored in
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.IR *pwbufp .
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.PP
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The \fIpasswd\fP structure is defined in \fI<pwd.h>\fP as follows:
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.sp
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.in +4n
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.nf
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struct passwd {
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char *pw_name; /* username */
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char *pw_passwd; /* user password */
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uid_t pw_uid; /* user ID */
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gid_t pw_gid; /* group ID */
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char *pw_gecos; /* real name */
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char *pw_dir; /* home directory */
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char *pw_shell; /* shell program */
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};
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.fi
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.in
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.PP
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The maximum needed size for
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.I buf
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can be found using
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.BR sysconf (3)
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with the
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.B _SC_GETPW_R_SIZE_MAX
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parameter.
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.SH "RETURN VALUE"
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The
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.BR getpwnam ()
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and
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.BR getpwuid ()
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functions return a pointer to a
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.I passwd
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structure, or NULL if the matching entry is not found or
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an error occurs.
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If an error occurs,
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.I errno
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is set appropriately.
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If one wants to check
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.I errno
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after the call, it should be set to zero before the call.
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.LP
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The return value may point to static area, and may be overwritten
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by subsequent calls to
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.BR getpwent (3),
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.BR getpwnam (),
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or
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.BR getpwuid ().
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.LP
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The
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.BR getpwnam_r ()
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and
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.BR getpwuid_r ()
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functions return
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zero on success.
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In case of error, an error number is returned.
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.SH ERRORS
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.TP
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.BR 0 " or " ENOENT " or " ESRCH " or " EBADF " or " EPERM " or ... "
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The given
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.I name
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or
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.I uid
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was not found.
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.TP
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.B EINTR
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A signal was caught.
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.TP
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.B EIO
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I/O error.
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.TP
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.B EMFILE
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The maximum number
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.RB ( OPEN_MAX )
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of files was open already in the calling process.
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.TP
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.B ENFILE
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The maximum number of files was open already in the system.
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.TP
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.B ENOMEM
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.\" not in POSIX
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Insufficient memory to allocate passwd structure.
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.\" This structure is static, allocated 0 or 1 times. No memory leak. (libc45)
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.TP
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.B ERANGE
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Insufficient buffer space supplied.
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.SH FILES
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.TP
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.I /etc/passwd
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local password database file
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001
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.SH NOTES
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The formulation given above under "RETURN VALUE" is from POSIX.1-2001.
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It does not call "not found" an error, and hence does not specify what value
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.I errno
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might have in this situation.
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But that makes it impossible to recognize
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errors.
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One might argue that according to POSIX
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.I errno
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should be left unchanged if an entry is not found.
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Experiments on various
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Unix-like systems show that lots of different values occur in this
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situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM and probably others.
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.\" more precisely:
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.\" AIX 5.1 - gives ESRCH
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.\" OSF1 4.0g - gives EWOULDBLOCK
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.\" libc, glibc, Irix 6.5 - give ENOENT
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.\" FreeBSD 4.8, OpenBSD 3.2, NetBSD 1.6 - give EPERM
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.\" SunOS 5.8 - gives EBADF
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.\" Tru64 5.1b, HP-UX-11i, SunOS 5.7 - give 0
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The
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.I pw_dir
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field contains the name of the initial working directory of the user.
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Login programs use the value of this field to initialize the
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.B HOME
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environment variable for the login shell.
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An application that wants to determine its user's home directory
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should inspect the value of
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.B HOME
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(rather than the value
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.IR getpwuid(getuid())\->pw_dir )
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since this allows the user to modify their notion of
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"the home directory" during a login session.
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To determine the (initial) home directory of another user,
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it is necessary to use
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.I getpwnam("username")\->pw_dir
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or similar.
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.SH "SEE ALSO"
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.BR endpwent (3),
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.BR fgetpwent (3),
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.BR getgrnam (3),
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.BR getpw (3),
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.BR getpwent (3),
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.BR putpwent (3),
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.BR setpwent (3),
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.BR passwd (5)
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