symlinkat(2)

1SYMLINK(2)                 Linux Programmer's Manual                SYMLINK(2)
2
3
4

NAME

6       symlink, symlinkat - make a new name for a file
7

SYNOPSIS

9       #include <unistd.h>
10
11       int symlink(const char *target, const char *linkpath);
12
13       #include <fcntl.h>           /* Definition of AT_* constants */
14       #include <unistd.h>
15
16       int symlinkat(const char *target, int newdirfd, const char *linkpath);
17
18   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
19
20       symlink():
21           _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
22               || /* Glibc versions <= 2.19: */ _BSD_SOURCE
23
24       symlinkat():
25           Since glibc 2.10:
26               _POSIX_C_SOURCE >= 200809L
27           Before glibc 2.10:
28               _ATFILE_SOURCE
29

DESCRIPTION

31       symlink()  creates  a  symbolic  link named linkpath which contains the
32       string target.
33
34       Symbolic links are interpreted at run time as if the  contents  of  the
35       link  had  been substituted into the path being followed to find a file
36       or directory.
37
38       Symbolic links may contain ..  path components, which (if used  at  the
39       start of the link) refer to the parent directories of that in which the
40       link resides.
41
42       A symbolic link (also known as a soft link) may point  to  an  existing
43       file  or  to  a nonexistent one; the latter case is known as a dangling
44       link.
45
46       The permissions of a symbolic link are  irrelevant;  the  ownership  is
47       ignored  when following the link, but is checked when removal or renam‐
48       ing of the link is requested and the link is in a  directory  with  the
49       sticky bit (S_ISVTX) set.
50
51       If linkpath exists, it will not be overwritten.
52
53   symlinkat()
54       The  symlinkat()  system  call operates in exactly the same way as sym‐
55       link(), except for the differences described here.
56
57       If the pathname given in linkpath is relative, then it  is  interpreted
58       relative  to  the directory referred to by the file descriptor newdirfd
59       (rather than relative to the current working directory of  the  calling
60       process, as is done by symlink() for a relative pathname).
61
62       If  linkpath  is  relative  and newdirfd is the special value AT_FDCWD,
63       then linkpath is interpreted relative to the current working  directory
64       of the calling process (like symlink()).
65
66       If linkpath is absolute, then newdirfd is ignored.
67

RETURN VALUE

69       On  success,  zero is returned.  On error, -1 is returned, and errno is
70       set appropriately.
71

ERRORS

73       EACCES Write access to the directory containing linkpath is denied,  or
74              one  of  the  directories in the path prefix of linkpath did not
75              allow search permission.  (See also path_resolution(7).)
76
77       EDQUOT The user's  quota  of  resources  on  the  filesystem  has  been
78              exhausted.   The  resources  could  be  inodes  or  disk blocks,
79              depending on the filesystem implementation.
80
81       EEXIST linkpath already exists.
82
83       EFAULT target or linkpath points outside your accessible address space.
84
85       EIO    An I/O error occurred.
86
87       ELOOP  Too many symbolic links were encountered in resolving linkpath.
88
89       ENAMETOOLONG
90              target or linkpath was too long.
91
92       ENOENT A directory component in linkpath does not exist or  is  a  dan‐
93              gling symbolic link, or target or linkpath is an empty string.
94
95       ENOMEM Insufficient kernel memory was available.
96
97       ENOSPC The device containing the file has no room for the new directory
98              entry.
99
100       ENOTDIR
101              A component used as a directory in linkpath is not, in  fact,  a
102              directory.
103
104       EPERM  The filesystem containing linkpath does not support the creation
105              of symbolic links.
106
107       EROFS  linkpath is on a read-only filesystem.
108
109       The following additional errors can occur for symlinkat():
110
111       EBADF  newdirfd is not a valid file descriptor.
112
113       ENOENT linkpath is a relative pathname and newdirfd refers to a  direc‐
114              tory that has been deleted.
115
116       ENOTDIR
117              linkpath is relative and newdirfd is a file descriptor referring
118              to a file other than a directory.
119

VERSIONS

121       symlinkat() was added to Linux in kernel 2.6.16;  library  support  was
122       added to glibc in version 2.4.
123

CONFORMING TO

125       symlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.
126
127       symlinkat(): POSIX.1-2008.
128

NOTES

130       No checking of target is done.
131
132       Deleting  the  name referred to by a symbolic link will actually delete
133       the file (unless it also has other hard links).  If  this  behavior  is
134       not desired, use link(2).
135
136   Glibc notes
137       On  older  kernels  where symlinkat() is unavailable, the glibc wrapper
138       function falls back to the use of symlink().  When linkpath is a  rela‐
139       tive  pathname,  glibc constructs a pathname based on the symbolic link
140       in /proc/self/fd that corresponds to the newdirfd argument.
141

COLOPHON

147       This  page  is  part of release 5.04 of the Linux man-pages project.  A
148       description of the project, information about reporting bugs,  and  the
149       latest     version     of     this    page,    can    be    found    at
150       https://www.kernel.org/doc/man-pages/.
151
152
153
154Linux                             2017-09-15                        SYMLINK(2)