getpwnam



GETPWNAM(3)               OpenBSD Programmer's Manual              GETPWNAM(3)


NAME

     getpwnam, getpwuid, getpwnam_r, getpwuid_r, setpassent - password
     database operations


SYNOPSIS

     #include <sys/types.h>
     #include <pwd.h>

     struct passwd *
     getpwnam(const char *login);

     struct passwd *
     getpwuid(uid_t uid);

     int
     getpwnam_r(const char *login, struct passwd *pwstore, char *buf, size_t
     buflen, struct passwd **result);

     int
     getpwuid_r(uid_t uid, struct passwd *pwstore, char *buf, size_t
     buflen, struct passwd **result);

     int
     setpassent(int stayopen);


DESCRIPTION

     These functions operate on the password database file which is described
     in passwd(5).  Each entry in the database is defined by the structure
     struct passwd found in the include file <pwd.h>:

           struct passwd {
                   char    *pw_name;       /* user name */
                   char    *pw_passwd;     /* encrypted password */
                   uid_t   pw_uid;         /* user uid */
                   gid_t   pw_gid;         /* user gid */
                   time_t  pw_change;      /* password change time */
                   char    *pw_class;      /* user access class */
                   char    *pw_gecos;      /* Honeywell login info */
                   char    *pw_dir;        /* home directory */
                   char    *pw_shell;      /* default shell */
                   time_t  pw_expire;      /* account expiration */
           };

     The functions getpwnam() and getpwuid() search the password database for
     the given login name or user ID, respectively, always returning the first
     one encountered.

     The re-entrant versions, getpwnam_r() and getpwuid_r(), behave similarly
     but the various strings associated with the result are stored in buf, and
     pwstore is updated to reference those strings.

     setpassent() accomplishes two purposes.  First, it causes getpwent(3) to
     ``rewind'' to the beginning of the database.  Additionally, if stayopen
     is non-zero, file descriptors are left open, significantly speeding up
     subsequent accesses for the lookup routines.  These file descriptors can
     be closed by a call to endpwent(3).

     It is dangerous for long-running programs to keep the file descriptors
     open as the database will become out of date if it is updated while the
     program is running.  Furthermore, programs that run child processes
     should be careful to call endpwent(3) to close these descriptors before
     calling execve(2) or system(3).

     These routines have been written to ``shadow'' the password file, that
     is, allow only certain programs to have access to the encrypted password.
     If the process which calls them has an effective UID of 0 or has the
     ``_shadow'' group in its group vector, the encrypted password will be
     returned, otherwise, the password field of the returned structure will
     point to the string `*'.


YP SUPPORT

     If YP is active, the functions getpwnam() and getpwnam_r() also use the
     master.passwd.byname YP map (if available) or the passwd.byname YP map;
     and the functions getpwuid() and getpwuid_r() also use the
     master.passwd.byuid YP map (if available) or the passwd.byuid YP map.
     This is in addition to the passwd file, and respects the order of both
     normal and YP entries in the passwd file.


RETURN VALUES

     The functions getpwnam() and getpwuid() return a valid pointer to a
     passwd structure on success or a null pointer if end-of-file is reached
     or an error occurs.

     The functions getpwnam_r() and getpwuid_r() update result to point to
     pwstore and then return 0 on success.

     The setpassent() function returns 0 on failure or 1 on success.


FILES

     /etc/pwd.db         insecure password database file
     /etc/spwd.db        secure password database file
     /etc/master.passwd  current password file
     /etc/passwd         a Version 7 format password file


SEE ALSO

     getlogin(2), getgrent(3), getgrouplist(3), getpwent(3), pw_dup(3),
     passwd(5), Makefile.yp(8), pwd_mkdb(8), vipw(8), yp(8)


HISTORY

     A predecessor to getpwuid(), getpw(), first appeared in Version 4 AT&T
     UNIX.  The getpwnam() and getpwuid() functions appeared in Version 7 AT&T
     UNIX.  The setpassent() function appeared in 4.3BSD-Reno.


BUGS

     The getpwnam() and getpwuid() functions store their results in an
     internal static buffer and return a pointer to that buffer.  Subsequent
     calls to getpwent(), getpwnam(), or getpwuid() will overwrite the same
     buffer.

OpenBSD 5.4                      July 17, 2013                     OpenBSD 5.4

[Unix Hosting | Open-Source | Contact Us]
[Engineering & Automation | Software Development | Server Applications]