Name
getuid, geteuid - get user identityLibrary
Standard C library ( libc ", " -lc )Synopsis
#include <unistd.h> uid_t getuid(void); uid_t geteuid(void);
Description
getuid() returns the real user ID of the calling process.geteuid() returns the effective user ID of the calling process.
Errors
These functions are always successful and never modifyerrno
. Standards
POSIX.1-2008.History
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.
See Also
- getresuid(2),
- setreuid(2),
- setuid(2),
- credentials(7)