1unlink(2) System Calls unlink(2)
2
6 unlink, unlinkat - remove directory entry
7
9 #include <unistd.h>
10 int unlink(const char *path);
12 int unlinkat(int dirfd, const char *path, int flag);
15
18 The unlink() function removes a link to a file. If path names a sym‐
19 bolic link, unlink() removes the symbolic link named by path and does
20 not affect any file or directory named by the contents of the symbolic
21 link. Otherwise, unlink() removes the link named by the pathname
22 pointed to by path and decrements the link count of the file referenced
23 by the link.
24 The unlinkat() function also removes a link to a file. See fsattr(5).
27 If the flag argument is 0, the behavior of unlinkat() is the same as
28 unlink() except in the processing of its path argument. If path is
29 absolute, unlinkat() behaves the same as unlink() and the dirfd argu‐
30 ment is unused. If path is relative and dirfd has the value AT_FDCWD,
31 defined in <fcntl.h>, unlinkat() also behaves the same as unlink().
32 Otherwise, path is resolved relative to the directory referenced by the
33 dirfd argument.
34 If the flag argument is set to the value AT_REMOVEDIR, defined in
37 <fcntl.h>, unlinkat() behaves the same as rmdir(2) except in the pro‐
38 cessing of the path argument as described above.
39 When the file's link count becomes 0 and no process has the file open,
42 the space occupied by the file will be freed and the file is no longer
43 accessible. If one or more processes have the file open when the last
44 link is removed, the link is removed before unlink() or unlinkat()
45 returns, but the removal of the file contents is postponed until all
46 references to the file are closed.
47 If the path argument is a directory and the filesystem supports
50 unlink() and unlinkat() on directories, the directory is unlinked from
51 its parent with no cleanup being performed. In UFS, the disconnected
52 directory will be found the next time the filesystem is checked with
53 fsck(1M). The unlink() and unlinkat() functions will not fail simply
54 because a directory is not empty. The user with appropriate privileges
55 can orphan a non-empty directory without generating an error message.
56 If the path argument is a directory and the filesystem does not support
59 unlink() and unlink() on directories (for example, ZFS), the call will
60 fail with errno set to EPERM.
61 Upon successful completion, unlink() and unlinkat() will mark for
64 update the st_ctime and st_mtime fields of the parent directory. If
65 the file's link count is not 0, the st_ctime field of the file will be
66 marked for update.
67
69 Upon successful completion, 0 is returned. Otherwise, −1 is returned,
70 errno is set to indicate the error, and the file is not unlinked.
71
73 The unlink() and unlinkat() functions will fail if:
74 EACCES Search permission is denied for a component of the path
76 prefix, or write permission is denied on the directory
77 containing the link to be removed.
78 EACCES The parent directory has the sticky bit set and the
81 file is not writable by the user, the user does not own
82 the parent directory, the user does not own the file,
83 and the user is not a privileged user.
84 EBUSY The entry to be unlinked is the mount point for a
87 mounted file system.
88 EFAULT The path argument points to an illegal address.
91 EILSEQ The path argument includes non-UTF8 characters and the
94 file system accepts only file names where all charac‐
95 ters are part of the UTF-8 character codeset.
96 EINTR A signal was caught during the execution of the
99 unlink() function.
100 ELOOP Too many symbolic links were encountered in translating
103 path.
104 ENAMETOOLONG The length of the path argument exceeds PATH_MAX, or
107 the length of a path component exceeds NAME_MAX while
108 _POSIX_NO_TRUNC is in effect.
109 ENOENT The named file does not exist or is a null pathname.
112 ENOLINK The path argument points to a remote machine and the
115 link to that machine is no longer active.
116 ENOTDIR A component of the path prefix is not a directory or
119 the provided directory descriptor for unlinkat() is not
120 AT_FDCWD or does not reference a directory.
121 EPERM The named file is a directory and {PRIV_SYS_LINKDIR} is
124 not asserted in the effective set of the calling
125 process, or the filesystem implementation does not sup‐
126 port unlink() or unlinkat() on directories.
127 EROFS The directory entry to be unlinked is part of a read-
130 only file system.
131 The unlink() and unlinkat() functions may fail if:
135 ENAMETOOLONG Pathname resolution of a symbolic link produced an
137 intermediate result whose length exceeds {PATH_MAX}.
138 ETXTBSY The entry to be unlinked is the last directory entry to
141 a pure procedure (shared text) file that is being exe‐
142 cuted.
143
146 Applications should use rmdir(2) to remove a directory.
147
149 See attributes(5) for descriptions of the following attributes:
150 ┌─────────────────────────────┬─────────────────────────────┐
155 │ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
156 ├─────────────────────────────┼─────────────────────────────┤
157 │Interface Stability │unlink() is Standard; │
158 │ │unlinkat() is Evolving │
159 ├─────────────────────────────┼─────────────────────────────┤
160 │MT-Level │Async-Signal-Safe │
161 └─────────────────────────────┴─────────────────────────────┘
162
164 rm(1), close(2), link(2), open(2), rmdir(2), remove(3C), attributes(5),
165 privileges(5), fsattr(5)
166SunOS 5.11 18 May 2007 unlink(2)