GETPWNAM(3) Linux Programmer's Manual GETPWNAM(3)
NAME
getpwnam, getpwnam_r, getpwuid, getpwuid_r - get password file(1,n) entry
SYNOPSIS
#include <sys/types.h>
#include <pwd.h>
struct passwd(1,5) *getpwnam(const char *name);
struct passwd(1,5) *getpwuid(uid_t uid);
int getpwnam_r(const char *name, struct passwd(1,5) *pwbuf,
char *buf, size_t buflen, struct passwd(1,5) **pwbufp);
int getpwuid_r(uid_t uid, struct passwd(1,5) *pwbuf,
char *buf, size_t buflen, struct passwd(1,5) **pwbufp);
DESCRIPTION
The getpwnam() function returns a pointer to a structure containing the
broken out fields of a line from /etc/passwd(1,5) 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(1,5) 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(1,5) structure in(1,8) the space pointed to by
pwbuf. This passwd(1,5) structure contains pointers to strings, and these
strings are stored in(1,8) the buffer buf of size buflen. A pointer to the
result (in(1,8) case of success) or NULL (in(1,8) case no entry was found or an
error(8,n) occurred) is stored in(1,8) *pwbufp.
The passwd(1,5) structure is defined in(1,8) <pwd.h> as follows:
struct passwd(1,5) {
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(1,5)
structure, or NULL if(3,n) the matching entry is not found or an error(8,n)
occurs. If an error(8,n) occurs, errno is set(7,n,1 builtins) appropriately. If one wants to
check errno after the call, it should be set(7,n,1 builtins) 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(8,n), an error(8,n) value is returned.
ERRORS
0 or ENOENT or ESRCH or EBADF or EPERM or ...
The given name or uid was not found.
EINTR A signal(2,7) was caught.
EIO I/O error.
EMFILE The maximum number (OPEN_MAX) of files was open(2,3,n) already in(1,8) the
calling process.
ENFILE The maximum number of files was open(2,3,n) already in(1,8) the system.
ENOMEM Insufficient memory to allocate passwd(1,5) structure.
ERANGE Insufficient buffer space supplied.
FILES
/etc/passwd(1,5)
password database file(1,n)
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(8,n), hence does not
specify what value errno might have in(1,8) this situation. But that makes
it impossible to recognize errors. One might argue that according to
POSIX errno should be left unchanged if(3,n) an entry is not found. Experi-
ments on various Unix-like systems shows that lots of different values
occur in(1,8) this situation: 0, ENOENT, EBADF, ESRCH, EWOULDBLOCK, EPERM
and probably others.
SEE ALSO
endpwent(3), fgetpwent(3), getgrnam(3), getpw(3), getpwent(3), putp-
went(3), setpwent(3), passwd(1,5)(5)
GNU 1996-05-27 GETPWNAM(3)