cuserid() - return user ID (login name) as a string
#include <stdio.h>
char * cuserid (char *s)
The cuserid(3) function returns the login name of the real or effective owner of the process.
If s is NULL, then the function returns a pointer to a static buffer, which may be overwritten by subsequent calls to cuserid(3).
If s is not NULL, it's assumed to be a buffer that is at least {L_cuserid} bytes long; {L_cuserid} is defined in <stdio.h>.
If s is not NULL, cuserid(3) returns s; if s is NULL, cuserid(3) returns a pointer to an internal buffer.
If the login name was found, it will be in the appropriate buffer. If the login name could not be found, the buffer contains a null byte `\0'.
getlogin(2)
getpwnam(2)
getpwuid(2)
getuid(2)
geteuid(2)
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at webmaster@systemmanager.forsenergy.ru to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.
Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.