NAME

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 *pwd,


            char *buf, size_t buflen, struct passwd **result);

int getpwuid_r(uid_t uid, struct passwd *pwd,


            char *buf, size_t buflen, struct passwd **result);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

getpwnam_r(), getpwuid_r():

_POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _BSD_SOURCE || _SVID_SOURCE || _POSIX_SOURCE

DESCRIPTION

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 pwd. 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 *result.

The passwd structure is defined in <pwd.h> as follows:

struct passwd {
    char   *pw_name;       /* username */
    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 argument _SC_GETPW_R_SIZE_MAX.  

RETURN VALUE

The return value may point to a static area, and may be overwritten by subsequent calls to getpwent(3), getpwnam(), or getpwuid(). (Do not pass the returned pointer to free(3).)

On success, getpwnam_r() and getpwuid_r() return zero, and set *result to pwd. If no matching password record was found, these functions return 0 and store NULL in *result. In case of error, an error number is returned, and NULL is stored in *result.  

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

NOTES

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.  

EXAMPLE

#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>

int
main(int argc, char *argv[])
{
    struct passwd pwd;
    struct passwd *result;
    char *buf;
    size_t bufsize;
    int s;

    if (argc != 2) {
        fprintf(stderr, "Usage: %s username\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    bufsize = sysconf(_SC_GETPW_R_SIZE_MAX);
    if (bufsize == -1)          /* Value was indeterminate */
        bufsize = 16384;        /* Should be more than enough */

    buf = malloc(bufsize);
    if (buf == NULL) {
        perror("malloc");
        exit(EXIT_FAILURE);
    }

    s = getpwnam_r(argv[1], &pwd, buf, bufsize, &result);
    if (result == NULL) {
        if (s == 0)
            printf("Not found\n");
        else {
            errno = s;
            perror("getpwnam_r");
        }
        exit(EXIT_FAILURE);
    }

    printf("Name: %s; UID: %ld\n", pwd.pw_gecos, (long) pwd.pw_uid);
    exit(EXIT_SUCCESS);
}

SEE ALSO

COLOPHON

Index

NAME

SYNOPSIS

DESCRIPTION

RETURN VALUE

ERRORS

FILES

CONFORMING TO

NOTES

EXAMPLE

SEE ALSO

COLOPHON