NAME
getuid, geteuid – get user identitySYNOPSIS
#include <unistd.h>#include <sys/types.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.CONFORMING TO
POSIX.1-2001, 4.3BSD.NOTES
History
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.
Willie has over 15 years of experience in Linux system administration and DevOps. After managing infrastructure for startups and enterprises alike, he founded Command Linux to share the practical knowledge he wished he had when starting out. He oversees content strategy and contributes guides on server management, automation, and security.