Linux and UNIX Man Pages

Test Your Knowledge in Computers #420
Difficulty: Medium
JavaScript supports much of the structured programming syntax from C (e.g., if statements, while loops, switch statements, do while loops, etc.).
True or False?
Linux & Unix Commands - Search Man Pages

setreuid(2) [freebsd 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

Check Out this Related Man Page

setreuid(2)							   System Calls 						       setreuid(2)

NAME
setreuid - set real and effective user IDs SYNOPSIS
#include <unistd.h> int setreuid(uid_t ruid, uid_t euid); DESCRIPTION
The setreuid() function is used to set the real and effective user IDs of the calling process. If ruid is -1, the real user ID is not changed; if euid is -1, the effective user ID is not changed. The real and effective user IDs may be set to different values in the same call. If the {PRIV_PROC_SETID} privilege is asserted in the effective set of the calling process, the real user ID and the effective user ID can be set to any legal value. If the {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling process, either the real user ID can be set to the effective user ID, or the effective user ID can either be set to the saved set-user ID from execve() (seeexec(2)) or the real user ID. In either case, if the real user ID is being changed (that is, if ruid is not -1), or the effective user ID is being changed to a value not equal to the real user ID, the saved set-user ID is set equal to the new effective user ID. All privileges are required to change to uid 0. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned, errno is set to indicate the error, and neither of the user IDs will be changed. ERRORS
The setreuid() function will fail if: EINVAL The value of ruid or euid is less than 0 or greater than UID_MAX (defined in <limits.h>). EPERM The {PRIV_PROC_SETID} privilege is not asserted in the effective set of the calling processes and a change was specified other than changing the real user ID to the effective user ID, or changing the effective user ID to the real user ID or the saved set-user ID. See privileges(5) for additional restrictions which apply when changing to UID 0. USAGE
If a set-user-ID process sets its effective user ID to its real user ID, it can still set its effective user ID back to the saved set-user ID. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
exec(2), getuid(2), setregid(2), setuid(2), attributes(5), privileges(5), standards(5) SunOS 5.10 22 Mar 2004 setreuid(2)

Featured Tech Videos