Manpage of SYMLINK
SYMLINKSection: Linux Programmer's Manual (2)
NAMEsymlink, symlinkat - make a new name for a file
#include <unistd.h>int symlink(const char *target, const char *linkpath);#include <fcntl.h> /* Definition of AT_* constants */ #include <unistd.h>int symlinkat(const char *target, int newdirfd, const char *linkpath);Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
- _XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
- Since glibc 2.10:
- _POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
DESCRIPTIONsymlink() creates a symbolic link named linkpathwhich contains the string target.
Symbolic links are interpreted at run time as if theof the link had been substituted into the path being followed to find a file or directory.
Symbolic links may contain ..path components, which (if used at the start of the link) refer to the parent directories of that in which the link resides.
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.
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 (S_ISVTX) set.
symlinkat()The symlinkat() system call operates in exactly the same way as symlink(), except for the differences described here.
If the pathname given in linkpathis relative, then it is interpreted relative to the directory referred to by the file descriptor newdirfd(rather than relative to the current working directory of the calling process, as is done by symlink() for a relative pathname).
If linkpathis relative and newdirfdis the special value AT_FDCWD, then linkpathis interpreted relative to the current working directory of the calling process (like symlink()).
RETURN VALUEOn success, zero is returned. On error, -1 is returned, and errnois set appropriately.
- Write access to the directory containing linkpathis denied, or one of the directories in the path prefix of linkpathdid not allow search permission. (See also path_resolution(7).)
- 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.
- linkpathalready exists.
- target or linkpath points outside your accessible address space.
- An I/O error occurred.
- Too many symbolic links were encountered in resolving linkpath.
- target or linkpath was too long.
- A directory component in linkpathdoes not exist or is a dangling symbolic link, or targetor linkpathis an empty string.
- Insufficient kernel memory was available.
- The device containing the file has no room for the new directory entry.
- A component used as a directory in linkpathis not, in fact, a directory.
- The filesystem containing linkpathdoes not support the creation of symbolic links.
- linkpathis on a read-only filesystem.
The following additional errors can occur for symlinkat():
- newdirfdis not a valid file descriptor.
- linkpathis a relative pathname and newdirfdrefers to a directory that has been deleted.
- linkpathis relative and newdirfdis a file descriptor referring to a file other than a directory.
VERSIONSsymlinkat() was added to Linux in kernel 2.6.16; library support was added to glibc in version 2.4.
CONFORMING TOsymlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.
NOTESNo checking of targetis done.
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 link(2).
Glibc notesOn older kernels where symlinkat() is unavailable, the glibc wrapper function falls back to the use of symlink(). When linkpathis a relative pathname, glibc constructs a pathname based on the symbolic link in /proc/self/fdthat corresponds to the newdirfdargument.
SEE ALSOln(1), namei(1), lchown(2), link(2), lstat(2), open(2), readlink(2), rename(2), unlink(2), path_resolution(7), symlink(7)
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