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25 .TH LINKAT 2 2013-07-21 "Linux" "Linux Programmer's Manual"
27 linkat \- create a file link relative to directory file descriptors
30 .B #include <fcntl.h> /* Definition of AT_* constants */
31 .B #include <unistd.h>
33 .BI "int linkat(int " olddirfd ", const char *" oldpath ,
34 .BI " int " newdirfd ", const char *" newpath ", int " flags );
38 Feature Test Macro Requirements for glibc (see
39 .BR feature_test_macros (7)):
48 _XOPEN_SOURCE\ >=\ 700 || _POSIX_C_SOURCE\ >=\ 200809L
58 system call operates in exactly the same way as
60 except for the differences described in this manual page.
62 If the pathname given in
64 is relative, then it is interpreted relative to the directory
65 referred to by the file descriptor
67 (rather than relative to the current working directory of
68 the calling process, as is done by
70 for a relative pathname).
80 is interpreted relative to the current working
81 directory of the calling process (like
94 except that a relative pathname is interpreted relative
95 to the directory referred to by the file descriptor
98 The following values can be bitwise ORed in
101 .BR AT_EMPTY_PATH " (since Linux 2.6.39)"
102 .\" commit 11a7b371b64ef39fc5fb1b6f2218eef7c4d035e3
105 is an empty string, create a link to the file referenced by
107 (which may have been obtained using the
113 can refer to any type of file, not just a directory.
114 The caller must have the
115 .BR CAP_DAC_READ_SEARCH
116 capability in order to use this flag;
117 this prevents arbitrary users from creating hard links
118 using file descriptors received via a UNIX domain socket
119 (see the discussion of
124 .BR AT_SYMLINK_FOLLOW " (since Linux 2.6.18)"
129 if it is a symbolic link (like
137 to be dereferenced if it is a symbolic link.
139 Before kernel 2.6.18, the
141 argument was unused, and had to be specified as 0.
146 On error, \-1 is returned and
148 is set to indicate the error.
150 The same errors that occur for
154 The following additional errors can occur for
161 is not a valid file descriptor.
167 but the caller did not have the
168 .B CAP_DAC_READ_SEARCH
177 is a file descriptor referring to a file other than a directory;
184 was added to Linux in kernel 2.6.16;
185 library support was added to glibc in version 2.4.
191 for an explanation of the need for
196 .BR path_resolution (7),