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setreuid(2) [ultrix man page]

setreuid(2)							System Calls Manual						       setreuid(2)

Name
       setreuid - set real and effective user ID's

Syntax
       setreuid(ruid, euid)
       intruid, euid;

Description
       The  real  and  effective  user	ID's of the current process are set according to the arguments.  If ruid or euid is -1, the current uid is
       filled in by the system.

Return Values
       Upon successful completion, a value of zero (0) is returned.  Otherwise, a value of -1 is returned and errno is set to indicate the error.

Environment
       BSD
       If the process is superuser, or and matches with the real user ID, the effective user ID, or the saved set-user-id (as described in ), then
       the real, effective, and the saved set-user-id are set to and respectively.

       POSIX
       SYSTEM-FIVE
       When  your  program  is	compiled  in the POSIX or SYSTEM-FIVE mode, if both arguments to are -1, the system call returns a value of -1 and
       errno is set to [EINVAL].

       The following semantics apply when using the function:

       If the process is the superuser, the real, effective, and saved set-user-id (as described in ) are set to and respectively.

       If the process is not the superuser, but the and matches with the real user ID, the effective user ID (only  in	the  SYSTEM-FIVE  and  BSD
       environments), or the saved set-user-id, then the effective ID is set to The  real user ID and the saved set-user-id are left unchanged.

Diagnostics
       [EPERM]	      The  current  process is not the superuser and the and specified does not match with the real user ID, the effective user ID
		      (only in SYSTEM-FIVE and BSD environment), or the saved set-user-id.

See Also
       getuid(2), setregid(2), setuid(3)

																       setreuid(2)

Check Out this Related Man Page

SETREUID(2)						      BSD System Calls Manual						       SETREUID(2)

NAME
setreuid -- set real and effective user ID's LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <unistd.h> int setreuid(uid_t ruid, uid_t euid); DESCRIPTION
The real and effective user IDs of the current process are set according to the arguments. If ruid or euid is -1, the current uid is filled in by the system. Unprivileged users may change the real user ID to the effective user ID and vice-versa; only the super-user may make other changes. If the real user ID is changed (i.e. ruid is not -1) or the effective user ID is changed to something other than the real user ID, then the saved user ID will be set to the effective user ID. The setreuid() system call has been used to swap the real and effective user IDs in set-user-ID programs to temporarily relinquish the set- user-ID value. This purpose is now better served by the use of the seteuid(2) system call. When setting the real and effective user IDs to the same value, the standard setuid() system call is preferred. RETURN VALUES
The setreuid() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indi- cate the error. ERRORS
[EPERM] The current process is not the super-user and a change other than changing the effective user-id to the real user-id was specified. SEE ALSO
getuid(2), issetugid(2), seteuid(2), setuid(2) HISTORY
The setreuid() system call appeared in 4.2BSD. BSD
February 8, 2001 BSD

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