Ubuntu Manpages

getuid, geteuid

get user identity

#include <unistd.h>
#include <sys/types.h>

uid_t getuid(void);
uid_t geteuid(void);

getuid() returns the real user ID of the calling process.

geteuid() returns the effective user ID of the calling process.

These functions are always successful.

POSIX.1-2001, POSIX.1-2008, 4.3BSD.

In UNIX V6 the getuid() call returned (euid << 8) + uid. UNIX V7 introduced separate calls getuid() and geteuid().

The original Linux getuid() and geteuid() system calls supported only 16-bit user IDs. Subsequently, Linux 2.4 added getuid32() and geteuid32(), supporting 32-bit IDs. The glibc getuid() and geteuid() wrapper functions transparently deal with the variations across kernel versions.

getresuid(2), setreuid(2), setuid(2), credentials(7)

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