setuid(2) — Reliant UNIX 5.44c4

setuid(2)                                                         setuid(2)

NAME
     setuid, setgid - set user and group IDs

SYNOPSIS
     #include <sys/types.h>
     #include <unistd.h>

     int setuid(uidt uid);

     int setgid(gidt gid);

DESCRIPTION
     The setuid() system call sets the real user ID, effective user ID, and
     saved user ID of the calling process. The setgid() system call sets
     the real group ID, effective group ID, and saved group ID of the cal-
     ling process.

     At login time, the real user ID, effective user ID, and saved user ID
     of the login process are set to the login ID of the user responsible
     for the creation of the process. The same is true for the real, effec-
     tive, and saved group IDs; they are set to the group ID of the user
     responsible for the creation of the process.

     When a process calls exec(2) to execute a file, the user and/or group
     identifiers associated with the process can change. If the file exe-
     cuted is a "set-user-ID" file, the effective and saved user IDs of the
     process are set to the owner of the file executed. If the file exe-
     cuted is a "set-group-ID" file, the effective and saved group IDs of
     the process are set to the group of the file executed. If the file
     executed is not a "set-user-ID" or "setgroup-ID" file, the user ID,
     saved user ID, effective group ID, and saved group ID are not changed.

     setuid()   If the effective user ID of the process calling setuid() is
                the superuser, the real, effective, and saved user IDs are
                set to the uid.

                If the effective user ID of the calling process is not the
                superuser, but uid is either the real user ID or the saved
                user ID of the calling process, the effective user ID is
                set to uid.

     setgid()   If the effective user ID of the process calling setgid() is
                the superuser, the real, effective, and saved group IDs are
                set to the gid.

                If the effective user ID of the calling process is not the
                superuser, but gid is either the real group ID or the saved
                group ID of the calling process, the effective group ID is
                set to gid.






Page 1                       Reliant UNIX 5.44                Printed 11/98

setuid(2)                                                         setuid(2)

     setuid() and setgid() fail if one or more of the following apply:

     EPERM      In the case of setuid(), if the effective user ID is not
                the superuser, and the uid parameter does not match either
                the real or saved user IDs.

                In the case of setgid(), if the effective user ID is not
                the superuser, and the gid parameter does not match either
                the real or saved group IDs.

     EINVAL     uid or gid is out of the valid range.

RESULT
     Upon successful completion, a value of 0 is returned. Otherwise, a
     value of -1 is returned and errno is set to indicate the error.

SEE ALSO
     exec(2), getgroups(2), getuid(2), stat(5).




































Page 2                       Reliant UNIX 5.44                Printed 11/98

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