NAME

cuserid — get user name

LIBRARY

Compatibility Library (libcompat, -lcompat)

SYNOPSIS

#include <stdio.h>

char *
cuserid(char *buf);

DESCRIPTION

The cuserid() function returns a character string representation of the user name associated with the effective user ID of the calling process.

If buf is not the NULL pointer, the user name is copied into the memory referenced by buf. The argument buf is assumed to point to an array at least L_cuserid (as defined in the include file <stdio.h>) bytes long. Otherwise, the user name is copied to a static buffer.

RETURN VALUES

If buf is not the NULL pointer, buf is returned; otherwise the address of the static buffer is returned.

If the user name could not be determined, if buf is not the NULL pointer, the null character ‘\0’ will be stored at *buf; otherwise the NULL pointer is returned.

SEE ALSO

getlogin(2), getpwent(3)

STANDARDS

The cuserid() function conforms to IEEE Std 1003.1-1988 (“POSIX.1”).

BUGS

Due to irreconcilable differences in historic implementations, cuserid() was removed from the IEEE Std 1003.1-1990 (“POSIX.1”) standard. This implementation exists purely for compatibility with existing programs. New programs should use one of the following three alternatives to obtain the user name:

1. getlogin() to return the user's login name.
2. getpwuid(geteuid()) to return the user name associated with the calling process' effective user ID.
3. getpwuid(getuid()) to return the user name associated with the calling process' real user ID.