getuid(2)                                               System Calls Manual                                               getuid(2)

NAME
       getuid, geteuid - get user identity

LIBRARY
       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 modify errno.

STANDARDS
       POSIX.1-2001, POSIX.1-2008, 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 ge‐
       tuid32() 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 re‐
       turns 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)

Linux man-pages 6.03                                         2022-10-30                                                   getuid(2)