SYMLINK(2) System Calls Manual SYMLINK(2)

symlink, symlinkat — make symbolic link to a file

#include <unistd.h>

int
symlink(const char *path1, const char *path2);

int
symlinkat(const char *name1, int fd, const char *name2);

A symbolic link path2 is created to path1 (path2 is the name of the file created, path1 is the string used in creating the symbolic link). Either name may be an arbitrary path name; the files need not be on the same file system.

The () system call is equivalent to () except in the case where name2 specifies a relative path. In this case the symbolic link is created relative to the directory associated with the file descriptor fd instead of the current working directory. If symlinkat() is passed the special value AT_FDCWD in the fd parameter, the current working directory is used and the behavior is identical to a call to symlink().

Upon successful completion, a zero value is returned. If an error occurs, the error code is stored in errno and a -1 value is returned.

The symbolic link succeeds unless:

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Write permission is denied in the directory where the symbolic link is being created.
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A component of the path2 path prefix denies search permission.
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The directory in which the entry for the new symbolic link is being placed cannot be extended because the user's quota of disk blocks on the file system containing the directory has been exhausted.
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The new symbolic link cannot be created because the user's quota of disk blocks on the file system that will contain the symbolic link has been exhausted.
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The user's quota of inodes on the file system on which the symbolic link is being created has been exhausted.
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Path2 already exists.
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Path1 or path2 points outside the process's allocated address space.
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An I/O error occurs while making the directory entry or allocating the inode.
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An I/O error occurs while making the directory entry for path2, or allocating the inode for path2, or writing out the link contents of path2.
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Too many symbolic links are encountered in translating the pathname. This is taken to be indicative of a looping symbolic link.
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A component of a pathname exceeds {NAME_MAX} characters, or an entire path name exceeds {PATH_MAX} characters.
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A component of path2 does not name an existing file or path2 is an empty string.
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The directory in which the entry for the new symbolic link is being placed cannot be extended because there is no space left on the file system containing the directory.
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The new symbolic link cannot be created because there there is no space left on the file system that will contain the symbolic link.
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There are no free inodes on the file system on which the symbolic link is being created.
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A component of the path prefix of path2 names an existing file that is neither a directory nor a symbolic link to a directory, or path2 contains at least one non-<slash> character and ends with one or more trailing <slash> characters and the last pathname component names an existing file that is neither a directory nor a symbolic link to a directory.
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The file path2 would reside on a read-only file system.

In addition to the errors returned by the symlink(), the symlinkat() may fail if:

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The name2 argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor open for searching.
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The name2 argument is not an absolute path and fd is neither AT_FDCWD nor a file descriptor associated with a directory.
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The filename does not match the encoding rules.

ln(1), link(2), unlink(2), symlink(7)

The symlinkat() system call is expected to conform to POSIX.1-2008 .

The symlink() function call appeared in 4.2BSD. The symlinkat() system call appeared in OS X 10.10

June 4, 1993 BSD 4.2