Editing Symbolic link (section)

===Storage of symbolic links===
Early implementations of symbolic links stored the symbolic link information as data in regular files. The file contained the textual reference to the link's target, and the file mode bits indicated that the type of the file is a symbolic link.

This method was slow and an inefficient use of [[disk storage|disk-space]] on small systems.  An improvement, called '''fast symlinks''', allowed storage of the target path within the [[data structure]]s used for storing file information on disk ([[inode]]s). This space normally stores a list of disk [[Block (data storage)|block]] addresses allocated to a file. Thus, symlinks with short target paths are accessed quickly. Systems with fast symlinks often fall back to using the original method if the target path exceeds the available inode space. The original style is [[retronym|retroactively termed]] a '''slow symlink'''. It is also used for disk compatibility with other or older versions of operating systems.

Although storing the link value inside the inode saves a disk block and a disk read, the operating system still needs to parse the path name in the link, which always requires reading additional inodes and generally requires reading other, and potentially many, directories, processing both the list of files and the inodes of each of them until it finds a match with the link's path components. Only when a link points to a file in the same directory do "fast symlinks" provide significantly better performance than other symlinks.

The vast majority of POSIX-compliant implementations use fast symlinks. However, the [[POSIX]] standard does not require the entire set of file status information common to regular files to be implemented for symlinks. This allows implementations to use other solutions, such as storing symlink data in directory entries.

The [[file system permissions]] of a symbolic link are not used; the access modes of the target file are controlled by the target file's own permissions.  Some operating systems, such as FreeBSD, offer the ability to modify file permissions and filesystem attributes of a symbolic link, through <code>lchmod</code><ref>{{cite web |url=https://www.freebsd.org/cgi/man.cgi?query=lchmod&apropos=0&sektion=2&manpath=FreeBSD+11.0-RELEASE&arch=default&format=html |series=Manual pages for FreeBSD 11 |title=lchmod(2)}}</ref> and <code>lchflags</code><ref>{{cite web |url=https://www.freebsd.org/cgi/man.cgi?query=lchflags&apropos=0&sektion=2&manpath=FreeBSD+11.0-RELEASE&arch=default&format=html |series=Manual pages for FreeBSD 11 |title=lchflags(2)}}</ref> system calls respectively.

The reported size of a symlink is the number of characters in the path it points to.