| getuid(2) | System Calls Manual | getuid(2) |
getuid, geteuid - get user identity
Standard C library (libc, -lc)
#include <unistd.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 and never modify errno.
POSIX.1-2008.
POSIX.1-2001, 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.
On Alpha, instead of a pair of getuid() and geteuid() system calls, a single getxuid() system call is provided, which returns a pair of real and effective UIDs. The glibc getuid() and geteuid() wrapper functions transparently deal with this. See syscall(2) for details regarding register mapping.
getresuid(2), setreuid(2), setuid(2), credentials(7)
| 2023-03-30 | Linux man-pages 6.05.01 |