getuid, geteuid - get user identity

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.1-2001, 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.

       Standard C library (libc, -lc)

       getuid, geteuid - get user identity

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

Linux man-pages 6.9.1                              2024-05-02                                          getuid(2)

       POSIX.1-2008.

#include<unistd.h>uid_tgetuid(void);uid_tgeteuid(void);