Re: Programming Language Survey

[Hyman Rosen <hyrosen@mail.com>]

Preben Randhol wrote:
> What are softlinks?

They're UNIXy things. In UNIX, the unique designator for a
file is called an "inode" and represents a numeric index
into a data structure containing the files of a filesystem.
Directories consist of pairs of inode numbers and names.
Thus, it's perfectly possible for the same inode, and thus
its file, to be known by many names. These many names of a
file are called hard links. (The "hard" is a back formation
which came about after soft links were invented, like "analog"
watches.)

Because hard links represent a pointer into the filesystem,
you cannot make hard links point to files in different
filesystems. This became an increasing handicap as the
number of filesystems on a computer grew. So soft links were
invented. A soft link is simply a file which holds the name
of another file, and is specially marked as being such.
When someone attempts to open a named soft link, the file
to which it links is opened instead.

Soft links cause much more complexity than hard links. It's
possible for the target of a soft link to be missing, or to
create circular chains of links. They're subject to race
conditions, and opening long chains of them can be slow.