1 .\" Copyright (C) 2001 Andries Brouwer (aeb@cwi.nl)
3 .\" %%%LICENSE_START(VERBATIM)
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25 .\" [should really be seteuid.3]
26 .\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
27 .\" Added notes on capability requirements
29 .TH SETEUID 2 2012-07-02 "Linux" "Linux Programmer's Manual"
31 seteuid, setegid \- set effective user or group ID
33 .B #include <sys/types.h>
35 .B #include <unistd.h>
37 .BI "int seteuid(uid_t " euid );
39 .BI "int setegid(gid_t " egid );
42 Feature Test Macro Requirements for glibc (see
43 .BR feature_test_macros (7)):
50 _BSD_SOURCE || _POSIX_C_SOURCE\ >=\ 200112L || _XOPEN_SOURCE\ >=\ 600
55 sets the effective user ID of the calling process.
56 Unprivileged user processes may only set the effective user ID to the
57 real user ID, the effective user ID or the saved set-user-ID.
59 Precisely the same holds for
61 with "group" instead of "user".
64 .\" equals \-1, nothing is changed.
65 .\" (This is an artifact of the implementation in glibc of seteuid()
66 .\" using setresuid(2).)
68 On success, zero is returned.
69 On error, \-1 is returned, and
77 The calling process is not privileged (Linux: does not have the
79 capability in the case of
83 capability in the case of
89 is not the real user (group) ID, the effective user (group) ID,
90 or the saved set-user-ID (saved set-group-ID).
94 Setting the effective user (group) ID to the
95 saved set-user-ID (saved set-group-ID) is
96 possible since Linux 1.1.37 (1.1.38).
97 On an arbitrary system one should check
98 .BR _POSIX_SAVED_IDS .
100 Under libc4, libc5 and glibc 2.0
103 .BI setreuid(\-1, " euid" )
104 and hence may change the saved set-user-ID.
105 Under glibc 2.1 and later it is equivalent to
106 .BI setresuid(\-1, " euid" ", \-1)"
107 and hence does not change the saved set-user-ID.
108 Analogous remarks hold for
110 with the difference that the change in implementation from
111 .BI setregid(\-1, " egid" )
113 .BI setresgid(\-1, " egid" ", \-1)"
114 occurred in glibc 2.2 or 2.3 (depending on the hardware architecture).
116 According to POSIX.1,
122 to be the same value as the current effective user (group) ID,
123 and some implementations do not permit this.
129 .BR capabilities (7),
132 This page is part of release 3.65 of the Linux
135 A description of the project,
136 and information about reporting bugs,
138 \%http://www.kernel.org/doc/man\-pages/.