CUSERID(3) Library Functions Manual CUSERID(3)

cuserid — character login name of the user (LEGACY)

#include <stdio.h>

char *cuserid(char *s);

The cuserid() function generates a character representation of the name associated with the real or effective user ID of the process.

If s is a null pointer, this representation is generated in an area that may be static (and thus overwritten by subsequent calls to cuserid()), the address of which is returned. If s is not a null pointer, s is assumed to point to an array of at least {L_cuserid} bytes; the representation is deposited in this array. The symbolic constant {L_cuserid} is defined in <stdio.h> and has a value greater than 0.

If the application uses any of the _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS interfaces, the cuserid() function must be called with a non-NULL parameter.

If s is not a null pointer, s is returned. If s is not a null pointer and the login name cannot be found, the null byte `\0' will be placed at *s . If s is a null pointer and the login name cannot be found, cuserid() returns a null pointer. If s is a null pointer and the login name can be found, the address of a buffer (possibly static) containing the login name is returned.

No errors are defined.

None.

The functionality of cuserid() defined in the POSIX.1-1988 standard (and Issue 3 of this specification) differs from that of historical implementations (and Issue 2 of this specification). In the ISO POSIX-1 standard, cuserid() is removed completely. In this specification, therefore, both functionalities are allowed.

The Issue 2 functionality can be obtained by using: getpwuid(getuid())

The Issue 3 functionality can be obtained by using: getpwuid(geteuid())

None.

getlogin(3) , getpwnam(3) , getpwuid(3) , getuid(3) , geteuid(3) , <stdio.h> .

Derived from System V Release 2.0.

February 1997 posix.fail