1SETUID(2)                     System Calls Manual                    SETUID(2)
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NAME

6       setuid, seteuid,setgid,setegid - set user and group ID
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SYNOPSIS

9       #include <sys/types.h>
10       #include <unistd.h>
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12       int
13       setuid(uid)
14           uid_t uid
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16       int
17       seteuid(euid)
18           uid_t euid
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20       int
21       setgid(gid)
22           gid_t gid
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24       int
25       setegid(egid)
26           gid_t egid
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DESCRIPTION

29       The  setuid function sets the real and effective user IDs and the saved
30       set-user-ID of the current process to the specified value.  The  setuid
31       function  is permitted if the specified ID is equal to the real user ID
32       of the process, or if the effective user ID is that of the super user.
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34       The setgid function sets the real and effective group IDs and the saved
35       set-group-ID of the current process to the specified value.  The setgid
36       function is permitted if the specified ID is equal to the real group ID
37       of the process, or if the effective user ID is that of the super user.
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39       The seteuid function (setegid) sets the effective user ID (group ID) of
40       the current process.  The effective user ID may be set to the value  of
41       the  real user ID or the saved set-user-ID (see intro(2) and execve(2);
42       in this way, the effective user ID of a set-user-ID executable  may  be
43       toggled  by switching to the real user ID, then re-enabled by reverting
44       to the set-user-ID value.  Similarly, the effective group ID may be set
45       to the value of the real group ID or the saved set-user-ID.
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RETURN VALUES

48       Upon success, these functions return 0; otherwise -1 is returned.
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50       If  the  user  is  not  the super user, or the uid specified is not the
51       real, effective ID, or saved ID, these functions return -1.
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SEE ALSO

54       getuid(2), getgid(2)
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STANDARDS

57       The setuid and  setgid  functions  are  compliant  with  the  IEEE  Std
58       1003.1-1988   (``POSIX'')   specification   with  _POSIX_SAVED_IDS  not
59       defined.  The seteuid and setegid functions are extensions based on the
60       POSIX concept of _POSIX_SAVED_IDS , and have been proposed for a future
61       revision of the standard.
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654.2 Berkeley Distribution      December 3, 1997                      SETUID(2)