getpwnam

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



NAME
       getpwnam, getpwnam_r, getpwuid, getpwuid_r - get password file entry

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

       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 a line from /etc/passwd for the entry that matches
       the user name name.

       The getpwuid() function returns a pointer to a structure containing the
       broken out fields of a line from /etc/passwd for the entry that matches
       the user uid uid.

       The  getpwnam_r() and getpwuid_r() functions find 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 the 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(), getpwnam(), or getpwuid().

       The  getpwnam_r() and getpwuid_r() functions return zero on success. In
       case of error, an error value is returned.

ERRORS
       0 or ENOENT or ESRCH or EBADF or EPERM or ...
              The given name or uid was not found.

       ENOMEM Insufficient memory to allocate passwd structure.

       EIO    I/O error.

       EINTR  A signal was caught.

       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.

       ERANGE Insufficient buffer space supplied.

NOTE
       The user password database mostly refers to /etc/passwd.  However, with
       recent systems it also refers to network wide databases using NIS, LDAP
       and other local files as configured in /etc/nsswitch.conf.

FILES
       /etc/passwd
              password database file

       /etc/nsswitch.conf
              System Databases and Name Service Switch configuration file

CONFORMING TO
       SVID 3, BSD 4.3, POSIX 1003.1-2003

NOTES
       The  formulation  given  above  under  "RETURN  VALUE"  is  from  POSIX
       1003.1-2001.   It  does  not  call "not found" an error, 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.  Experi-
       ments  on various Unix-like systems shows that lots of different values
       occur in this situation: 0, ENOENT, EBADF,  ESRCH,  EWOULDBLOCK,  EPERM
       and probably others.

SEE ALSO
       fgetpwent(3),   getgrnam(3),   getpwent(3),  setpwent(3),  endpwent(3),
       getpw(3), putpwent(3), nsswitch.conf(5), passwd(5)



GNU                               2002-03-09                       GETPWNAM(3)