-
Notifications
You must be signed in to change notification settings - Fork 0
/
symlink.html
425 lines (296 loc) · 10.7 KB
/
symlink.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
<!-- Creator : groff version 1.22.4 -->
<!-- CreationDate: Wed Jan 29 11:25:45 2020 -->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta name="generator" content="groff -Thtml, see www.gnu.org">
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<meta name="Content-Style" content="text/css">
<style type="text/css">
p { margin-top: 0; margin-bottom: 0; vertical-align: top }
pre { margin-top: 0; margin-bottom: 0; vertical-align: top }
table { margin-top: 0; margin-bottom: 0; vertical-align: top }
h1 { text-align: center }
</style>
<title>SYMLINK</title>
</head>
<body>
<h1 align="center">SYMLINK</h1>
<a href="#NAME">NAME</a><br>
<a href="#SYNOPSIS">SYNOPSIS</a><br>
<a href="#DESCRIPTION">DESCRIPTION</a><br>
<a href="#RETURN VALUE">RETURN VALUE</a><br>
<a href="#ERRORS">ERRORS</a><br>
<a href="#VERSIONS">VERSIONS</a><br>
<a href="#CONFORMING TO">CONFORMING TO</a><br>
<a href="#NOTES">NOTES</a><br>
<a href="#SEE ALSO">SEE ALSO</a><br>
<a href="#COLOPHON">COLOPHON</a><br>
<hr>
<h2>NAME
<a name="NAME"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">symlink,
symlinkat - make a new name for a file</p>
<h2>SYNOPSIS
<a name="SYNOPSIS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>#include
<unistd.h></b></p>
<p style="margin-left:11%; margin-top: 1em"><b>int
symlink(const char *</b><i>target</i><b>, const char
*</b><i>linkpath</i><b>);</b></p>
<p style="margin-left:11%; margin-top: 1em"><b>#include
<fcntl.h></b> /* Definition of AT_* constants */
<b><br>
#include <unistd.h></b></p>
<p style="margin-left:11%; margin-top: 1em"><b>int
symlinkat(const char *</b><i>target</i><b>, int</b>
<i>newdirfd</i><b>, const char
*</b><i>linkpath</i><b>);</b></p>
<p style="margin-left:5%; margin-top: 1em">Feature Test
Macro Requirements for glibc (see
<b>feature_test_macros</b>(7)):</p>
<p style="margin-left:11%; margin-top: 1em"><b>symlink</b>():</p>
<p style="margin-left:17%;">_XOPEN_SOURCE >= 500
|| _POSIX_C_SOURCE >= 200112L <br>
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE</p>
<p style="margin-left:11%; margin-top: 1em"><b>symlinkat</b>():</p>
<p style="margin-left:17%;">Since glibc 2.10:</p>
<p style="margin-left:23%;">_POSIX_C_SOURCE >= 200809L</p>
<p style="margin-left:17%;">Before glibc 2.10:</p>
<p style="margin-left:23%;">_ATFILE_SOURCE</p>
<h2>DESCRIPTION
<a name="DESCRIPTION"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>symlink</b>()
creates a symbolic link named <i>linkpath</i> which contains
the string <i>target</i>.</p>
<p style="margin-left:11%; margin-top: 1em">Symbolic links
are interpreted at run time as if the contents of the link
had been substituted into the path being followed to find a
file or directory.</p>
<p style="margin-left:11%; margin-top: 1em">Symbolic links
may contain <i>..</i> path components, which (if used at the
start of the link) refer to the parent directories of that
in which the link resides.</p>
<p style="margin-left:11%; margin-top: 1em">A symbolic link
(also known as a soft link) may point to an existing file or
to a nonexistent one; the latter case is known as a dangling
link.</p>
<p style="margin-left:11%; margin-top: 1em">The permissions
of a symbolic link are irrelevant; the ownership is ignored
when following the link, but is checked when removal or
renaming of the link is requested and the link is in a
directory with the sticky bit (<b>S_ISVTX</b>) set.</p>
<p style="margin-left:11%; margin-top: 1em">If
<i>linkpath</i> exists, it will <i>not</i> be
overwritten.</p>
<p style="margin-left:11%; margin-top: 1em"><b>symlinkat()</b>
<br>
The <b>symlinkat</b>() system call operates in exactly the
same way as <b>symlink</b>(), except for the differences
described here.</p>
<p style="margin-left:11%; margin-top: 1em">If the pathname
given in <i>linkpath</i> is relative, then it is interpreted
relative to the directory referred to by the file descriptor
<i>newdirfd</i> (rather than relative to the current working
directory of the calling process, as is done by
<b>symlink</b>() for a relative pathname).</p>
<p style="margin-left:11%; margin-top: 1em">If
<i>linkpath</i> is relative and <i>newdirfd</i> is the
special value <b>AT_FDCWD</b>, then <i>linkpath</i> is
interpreted relative to the current working directory of the
calling process (like <b>symlink</b>()).</p>
<p style="margin-left:11%; margin-top: 1em">If
<i>linkpath</i> is absolute, then <i>newdirfd</i> is
ignored.</p>
<h2>RETURN VALUE
<a name="RETURN VALUE"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">On success,
zero is returned. On error, -1 is returned, and <i>errno</i>
is set appropriately.</p>
<h2>ERRORS
<a name="ERRORS"></a>
</h2>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em"><b>EACCES</b></p></td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em">Write access to the directory
containing <i>linkpath</i> is denied, or one of the
directories in the path prefix of <i>linkpath</i> did not
allow search permission. (See also
<b>path_resolution</b>(7).)</p> </td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>EDQUOT</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>The user’s quota of resources on the filesystem
has been exhausted. The resources could be inodes or disk
blocks, depending on the filesystem implementation.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>EEXIST</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>linkpath</i> already exists.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>EFAULT</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>target</i> or <i>linkpath</i> points outside your
accessible address space.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>EIO</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>An I/O error occurred.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ELOOP</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Too many symbolic links were encountered in resolving
<i>linkpath</i>.</p> </td></tr>
</table>
<p style="margin-left:11%;"><b>ENAMETOOLONG</b></p>
<p style="margin-left:22%;"><i>target</i> or
<i>linkpath</i> was too long.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ENOENT</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>A directory component in <i>linkpath</i> does not exist
or is a dangling symbolic link, or <i>target</i> or
<i>linkpath</i> is an empty string.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ENOMEM</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>Insufficient kernel memory was available.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ENOSPC</b></p></td>
<td width="2%"></td>
<td width="78%">
<p>The device containing the file has no room for the new
directory entry.</p></td></tr>
</table>
<p style="margin-left:11%;"><b>ENOTDIR</b></p>
<p style="margin-left:22%;">A component used as a directory
in <i>linkpath</i> is not, in fact, a directory.</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>EPERM</b></p></td>
<td width="4%"></td>
<td width="78%">
<p>The filesystem containing <i>linkpath</i> does not
support the creation of symbolic links.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="7%">
<p><b>EROFS</b></p></td>
<td width="4%"></td>
<td width="78%">
<p><i>linkpath</i> is on a read-only filesystem.</p></td></tr>
</table>
<p style="margin-left:11%; margin-top: 1em">The following
additional errors can occur for <b>symlinkat</b>():</p>
<table width="100%" border="0" rules="none" frame="void"
cellspacing="0" cellpadding="0">
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p style="margin-top: 1em"><b>EBADF</b></p></td>
<td width="2%"></td>
<td width="78%">
<p style="margin-top: 1em"><i>newdirfd</i> is not a valid
file descriptor.</p></td></tr>
<tr valign="top" align="left">
<td width="11%"></td>
<td width="9%">
<p><b>ENOENT</b></p></td>
<td width="2%"></td>
<td width="78%">
<p><i>linkpath</i> is a relative pathname and
<i>newdirfd</i> refers to a directory that has been
deleted.</p> </td></tr>
</table>
<p style="margin-left:11%;"><b>ENOTDIR</b></p>
<p style="margin-left:22%;"><i>linkpath</i> is relative and
<i>newdirfd</i> is a file descriptor referring to a file
other than a directory.</p>
<h2>VERSIONS
<a name="VERSIONS"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>symlinkat</b>()
was added to Linux in kernel 2.6.16; library support was
added to glibc in version 2.4.</p>
<h2>CONFORMING TO
<a name="CONFORMING TO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>symlink</b>():
SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.</p>
<p style="margin-left:11%; margin-top: 1em"><b>symlinkat</b>():
POSIX.1-2008.</p>
<h2>NOTES
<a name="NOTES"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">No checking of
<i>target</i> is done.</p>
<p style="margin-left:11%; margin-top: 1em">Deleting the
name referred to by a symbolic link will actually delete the
file (unless it also has other hard links). If this behavior
is not desired, use <b>link</b>(2).</p>
<p style="margin-left:11%; margin-top: 1em"><b>Glibc
notes</b> <br>
On older kernels where <b>symlinkat</b>() is unavailable,
the glibc wrapper function falls back to the use of
<b>symlink</b>(). When <i>linkpath</i> is a relative
pathname, glibc constructs a pathname based on the symbolic
link in <i>/proc/self/fd</i> that corresponds to the
<i>newdirfd</i> argument.</p>
<h2>SEE ALSO
<a name="SEE ALSO"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em"><b>ln</b>(1),
<b>namei</b>(1), <b>lchown</b>(2), <b>link</b>(2),
<b>lstat</b>(2), <b>open</b>(2), <b>readlink</b>(2),
<b>rename</b>(2), <b>unlink</b>(2),
<b>path_resolution</b>(7), <b>symlink</b>(7)</p>
<h2>COLOPHON
<a name="COLOPHON"></a>
</h2>
<p style="margin-left:11%; margin-top: 1em">This page is
part of release 5.02 of the Linux <i>man-pages</i> project.
A description of the project, information about reporting
bugs, and the latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.</p>
<hr>
</body>
</html>