1chown(2) System Calls chown(2)
2
6 chown, lchown, fchown, fchownat - change owner and group of a file
7
9 #include <unistd.h>
10 #include <sys/types.h>
11 int chown(const char *path, uid_t owner, gid_t group);
13 int lchown(const char *path, uid_t owner, gid_t group);
16 int fchown(int fildes, uid_t owner, gid_t group);
19 int fchownat(int fildes, const char *path, uid_t owner,
22 gid_t group, int flag);
23
26 The chown() function sets the owner ID and group ID of the file speci‐
27 fied by path or referenced by the open file descriptor fildes to owner
28 and group respectively. If owner or group is specified as −1, chown()
29 does not change the corresponding ID of the file.
30 The lchown() function sets the owner ID and group ID of the named file
33 in the same manner as chown(), unless the named file is a symbolic
34 link. In this case, lchown() changes the ownership of the symbolic link
35 file itself, while chown() changes the ownership of the file or direc‐
36 tory to which the symbolic link refers.
37 The fchownat() function sets the owner ID and group ID of the named
40 file in the same manner as chown(). If, however, the path argument is
41 relative, the path is resolved relative to the fildes argument rather
42 than the current working directory. If the fildes argument has the
43 special value AT_FDCWD, the path resolution reverts back to current
44 working directory relative. If the flag argument is set to SYMLNK, the
45 function behaves like lchown() with respect to symbolic links. If the
46 path argument is absolute, the fildes argument is ignored. If the path
47 argument is a null pointer, the function behaves like fchown().
48 If chown(), lchown(), fchown(), or fchownat() is invoked by a process
51 that does not have {PRIV_FILE_SETID} asserted in its effective set, the
52 set-user-ID and set-group-ID bits of the file mode, S_ISUID and
53 S_ISGID respectively, are cleared (see chmod(2)). Additional restric‐
54 tions apply when changing the ownership to uid 0.
55 The operating system defines several privileges to override restric‐
58 tions on the chown() family of functions. When the {PRIV_FILE_CHOWN}
59 privilege is asserted in the effective set of the current process,
60 there are no restrictions except in the special circumstances of chang‐
61 ing ownership to or from uid 0. When the {PRIV_FILE_CHOWN_SELF} privi‐
62 lege is asserted, ownership changes are restricted to the files of
63 which the ownership matches the effective user ID of the current
64 process. If neither privilege is asserted in the effective set of the
65 calling process, ownership changes are limited to changes of the group
66 of the file to the list of supplementary group IDs and the effective
67 group ID.
68 The operating system provides a configuration option,
71 {_POSIX_CHOWN_RESTRICTED}, to control the default behavior of processes
72 and the behavior of the NFS server. If {_POSIX_CHOWN_RESTRICTED} is
73 not in effect, the privilege {PRIV_FILE_CHOWN_SELF} is asserted in the
74 inheritable set of all processes unless overridden by policy.conf(4) or
75 user_attr(4). To set this configuration option, include the following
76 line in /etc/system:
77 set rstchown = 1
80 To disable this option, include the following line in /etc/system:
83 set rstchown = 0
86 See system(4) and fpathconf(2).
89 Upon successful completion, chown(), fchown() and lchown() mark for
92 update the st_ctime field of the file.
93
95 Upon successful completion, 0 is returned. Otherwise, −1 is returned,
96 the owner and group of the named file remain unchanged, and errno is
97 set to indicate the error.
98
100 All of these functions will fail if:
101 EPERM The effective user ID does not match the owner of the file and
103 the {PRIV_FILE_CHOWN} privilege is not asserted in the effec‐
104 tive set of the calling process, or the {PRIV_FILE_CHOWN_SELF}
105 privilege is not asserted in the effective set of the calling
106 process.
107 The chown(), lchown(), and fchownat() functions will fail if:
111 EACCES Search permission is denied on a component of the path
113 prefix of path.
114 EFAULT The path argument points to an illegal address and for
117 fchownat(), the file descriptor has the value AT_FDCWD.
118 EINTR A signal was caught during the execution of the chown()
121 or lchown() function.
122 EINVAL The group or owner argument is out of range.
125 EIO An I/O error occurred while reading from or writing to
128 the file system.
129 ELOOP Too many symbolic links were encountered in translating
132 path.
133 ENAMETOOLONG The length of the path argument exceeds {PATH_MAX}, or
136 the length of a path component exceeds {NAME_MAX} while
137 {_POSIX_NO_TRUNC} is in effect.
138 ENOLINK The path argument points to a remote machine and the
141 link to that machine is no longer active.
142 ENOENT Either a component of the path prefix or the file
145 referred to by path does not exist or is a null path‐
146 name.
147 ENOTDIR A component of the path prefix of path is not a direc‐
150 tory, or the path supplied to fchownat() is relative
151 and the file descriptor provided does not refer to a
152 valid directory.
153 EROFS The named file resides on a read-only file system.
156 The fchown() and fchownat() functions will fail if:
160 EBADF For fchown() the fildes argument is not an open file
162 descriptor and.
163 For fchownat(), the path argument is not absolute and the
165 fildes argument is not AT_FDCWD or an open file descriptor.
166 EIO An I/O error occurred while reading from or writing to the
169 file system.
170 EINTR A signal was caught during execution of the function.
173 ENOLINK The fildes argument points to a remote machine and the link
176 to that machine is no longer active.
177 EINVAL The group or owner argument is out of range.
180 EROFS The named file referred to by fildes resides on a read-only
183 file system.
184
187 See attributes(5) for descriptions of the following attributes:
188 ┌─────────────────────────────┬─────────────────────────────┐
193 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
194 ├─────────────────────────────┼─────────────────────────────┤
195 │Interface Stability │See below. │
196 ├─────────────────────────────┼─────────────────────────────┤
197 │MT-Level │See below. │
198 └─────────────────────────────┴─────────────────────────────┘
199 The chown(), fchown(), and lchown() functions are Standard. The fchow‐
202 nat() function is Evolving.
203 The chown() and fchownat() functions are Async-Signal-Safe.
206
208 chgrp(1), chown(1), chmod(2), fpathconf(2), system(4), attributes(5),
209 standards(5)
210SunOS 5.11 9 Oct 2008 chown(2)