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12 .TH UNLINK 2 "May 18, 2007"
13 .SH NAME
14 unlink, unlinkat \- remove directory entry
15 .SH SYNOPSIS
16 .LP
17 .nf
18 #include <unistd.h>
19
20 \fBint\fR \fBunlink\fR(\fBconst char *\fR\fIpath\fR);
21 .fi
22
23 .LP
24 .nf
25 \fBint\fR \fBunlinkat\fR(\fBint\fR \fIdirfd\fR, \fBconst char *\fR\fIpath\fR, \fBint\fR \fIflag\fR);
26 .fi
27
28 .SH DESCRIPTION
29 .sp
30 .LP
31 The \fBunlink()\fR function removes a link to a file. If \fIpath\fR names a
32 symbolic link, \fBunlink()\fR removes the symbolic link named by \fIpath\fR and
33 does not affect any file or directory named by the contents of the symbolic
34 link. Otherwise, \fBunlink()\fR removes the link named by the pathname pointed
35 to by \fIpath\fR and decrements the link count of the file referenced by the
36 link.
37 .sp
38 .LP
39 The \fBunlinkat()\fR function also removes a link to a file. See
40 \fBfsattr\fR(5). If the \fIflag\fR argument is 0, the behavior of
41 \fBunlinkat()\fR is the same as \fBunlink()\fR except in the processing of its
42 \fIpath\fR argument. If \fIpath\fR is absolute, \fBunlinkat()\fR behaves the
43 same as \fBunlink()\fR and the \fIdirfd\fR argument is unused. If \fIpath\fR is
44 relative and \fIdirfd\fR has the value \fBAT_FDCWD\fR, defined in
45 <\fBfcntl.h\fR>, \fBunlinkat()\fR also behaves the same as \fBunlink()\fR.
46 Otherwise, \fIpath\fR is resolved relative to the directory referenced by the
47 \fIdirfd\fR argument.
48 .sp
49 .LP
50 If the \fIflag\fR argument is set to the value \fBAT_REMOVEDIR\fR, defined in
51 <\fBfcntl.h\fR>, \fBunlinkat()\fR behaves the same as \fBrmdir\fR(2) except in
52 the processing of the \fIpath\fR argument as described above.
53 .sp
54 .LP
55 When the file's link count becomes 0 and no process has the file open, the
56 space occupied by the file will be freed and the file is no longer accessible.
57 If one or more processes have the file open when the last link is removed, the
58 link is removed before \fBunlink()\fR or \fBunlinkat()\fR returns, but the
59 removal of the file contents is postponed until all references to the file are
60 closed.
61 .sp
62 .LP
63 If the \fIpath\fR argument is a directory and the filesystem supports
64 \fBunlink()\fR and \fBunlinkat()\fR on directories, the directory is unlinked
65 from its parent with no cleanup being performed. In UFS, the disconnected
66 directory will be found the next time the filesystem is checked with
67 \fBfsck\fR(1M). The \fBunlink()\fR and \fBunlinkat()\fR functions will not fail
68 simply because a directory is not empty. The user with appropriate privileges
69 can orphan a non-empty directory without generating an error message.
70 .sp
71 .LP
72 If the \fIpath\fR argument is a directory and the filesystem does not support
73 \fBunlink()\fR and \fBunlink()\fR on directories (for example, ZFS), the call
74 will fail with \fBerrno\fR set to \fBEPERM\fR.
75 .sp
76 .LP
77 Upon successful completion, \fBunlink()\fR and \fBunlinkat()\fR will mark for
78 update the \fBst_ctime\fR and \fBst_mtime\fR fields of the parent directory.
79 If the file's link count is not 0, the \fBst_ctime\fR field of the file will be
80 marked for update.
81 .SH RETURN VALUES
82 .sp
83 .LP
84 Upon successful completion, \fB0\fR is returned. Otherwise, \fB\(mi1\fR is
85 returned, \fBerrno\fR is set to indicate the error, and the file is not
86 unlinked.
87 .SH ERRORS
88 .sp
89 .LP
90 The \fBunlink()\fR and \fBunlinkat()\fR functions will fail if:
91 .sp
92 .ne 2
93 .na
94 \fB\fBEACCES\fR\fR
95 .ad
96 .RS 16n
97 Search permission is denied for a component of the \fIpath\fR prefix, or write
98 permission is denied on the directory containing the link to be removed.
99 .RE
100
101 .sp
102 .ne 2
103 .na
104 \fB\fBEACCES\fR\fR
105 .ad
106 .RS 16n
107 The parent directory has the sticky bit set and the file is not writable by the
108 user, the user does not own the parent directory, the user does not own the
109 file, and the user is not a privileged user.
110 .RE
111
112 .sp
113 .ne 2
114 .na
115 \fB\fBEBUSY\fR\fR
116 .ad
117 .RS 16n
118 The entry to be unlinked is the mount point for a mounted file system.
119 .RE
120
121 .sp
122 .ne 2
123 .na
124 \fB\fBEFAULT\fR\fR
125 .ad
126 .RS 16n
127 The \fIpath\fR argument points to an illegal address.
128 .RE
129
130 .sp
131 .ne 2
132 .na
133 \fB\fBEILSEQ\fR\fR
134 .ad
135 .RS 16n
136 The path argument includes non-UTF8 characters and the file system accepts only
137 file names where all characters are part of the UTF-8 character codeset.
138 .RE
139
140 .sp
141 .ne 2
142 .na
143 \fB\fBEINTR\fR\fR
144 .ad
145 .RS 16n
146 A signal was caught during the execution of the \fBunlink()\fR function.
147 .RE
148
149 .sp
150 .ne 2
151 .na
152 \fB\fBELOOP\fR\fR
153 .ad
154 .RS 16n
155 Too many symbolic links were encountered in translating \fIpath\fR.
156 .RE
157
158 .sp
159 .ne 2
160 .na
161 \fB\fBENAMETOOLONG\fR\fR
162 .ad
163 .RS 16n
164 The length of the \fIpath\fR argument exceeds \fBPATH_MAX\fR, or the length of
165 a \fIpath\fR component exceeds \fBNAME_MAX\fR while \fB_POSIX_NO_TRUNC\fR is in
166 effect.
167 .RE
168
169 .sp
170 .ne 2
171 .na
172 \fB\fBENOENT\fR\fR
173 .ad
174 .RS 16n
175 The named file does not exist or is a null pathname.
176 .RE
177
178 .sp
179 .ne 2
180 .na
181 \fB\fBENOLINK\fR\fR
182 .ad
183 .RS 16n
184 The \fIpath\fR argument points to a remote machine and the link to that machine
185 is no longer active.
186 .RE
187
188 .sp
189 .ne 2
190 .na
191 \fB\fBENOTDIR\fR\fR
192 .ad
193 .RS 16n
194 A component of the \fIpath\fR prefix is not a directory or the provided
195 directory descriptor for \fBunlinkat()\fR is not \fBAT_FDCWD\fR or does not
196 reference a directory.
197 .RE
198
199 .sp
200 .ne 2
201 .na
202 \fB\fBEPERM\fR\fR
203 .ad
204 .RS 16n
205 The named file is a directory and {\fBPRIV_SYS_LINKDIR\fR} is not asserted in
206 the effective set of the calling process, or the filesystem implementation does
207 not support \fBunlink()\fR or \fBunlinkat()\fR on directories.
208 .RE
209
210 .sp
211 .ne 2
212 .na
213 \fB\fBEROFS\fR\fR
214 .ad
215 .RS 16n
216 The directory entry to be unlinked is part of a read-only file system.
217 .RE
218
219 .sp
220 .LP
221 The \fBunlink()\fR and \fBunlinkat()\fR functions may fail if:
222 .sp
223 .ne 2
224 .na
225 \fB\fBENAMETOOLONG\fR\fR
226 .ad
227 .RS 16n
228 Pathname resolution of a symbolic link produced an intermediate result whose
229 length exceeds {\fBPATH_MAX\fR}.
230 .RE
231
232 .sp
233 .ne 2
234 .na
235 \fB\fBETXTBSY\fR\fR
236 .ad
237 .RS 16n
238 The entry to be unlinked is the last directory entry to a pure procedure
239 (shared text) file that is being executed.
240 .RE
241
242 .SH USAGE
243 .sp
244 .LP
245 Applications should use \fBrmdir\fR(2) to remove a directory.
246 .SH ATTRIBUTES
247 .sp
248 .LP
249 See \fBattributes\fR(5) for descriptions of the following attributes:
250 .sp
251
252 .sp
253 .TS
254 box;
255 c | c
256 l | l .
257 ATTRIBUTE TYPE ATTRIBUTE VALUE
258 _
259 Interface Stability T{
260 \fBunlink()\fR is Standard; \fBunlinkat()\fR is Evolving
261 T}
262 _
263 MT-Level Async-Signal-Safe
264 .TE
265
266 .SH SEE ALSO
267 .sp
268 .LP
269 \fBrm\fR(1), \fBclose\fR(2), \fBlink\fR(2), \fBopen\fR(2), \fBrmdir\fR(2),
270 \fBremove\fR(3C), \fBattributes\fR(5), \fBprivileges\fR(5), \fBfsattr\fR(5)