In most Unix and Unix-like systems, there are two kinds of "link". One is a "symbolic (or soft) link", and the other is a "hard link". Both of them are ways of pointing to a file or program that's in some other location in the file system than where it appears to be. (Another way to think of them is as "shortcuts".)A symbolic link can point to any location known to the system, whether it's physically part of the same file system or not. Hard links are generally limited to pointing to files within the same file system.
You don't have to be a privileged user to create a hard link; most of the time they aren't as desirable as soft links because with a hard link the file must be present to create the link. In addition, there are some restrictions about going across file systems with a hard link that do not exist as a restriction with a soft link.
Unix systems may be affected by viruses .. see related link.
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A hard link is an actual physical entity representing the link. i.e.--data file on a server.A symbolic link is a pointer to a physical entity. The purpose of a symbolic link is, if the object moves, the symbolic link is coded so no matter where the object physically resides, the database can find it. It requires less administration not having to update locations in files pointing to files that have moved. Symbolic links function similar to the short-cuts in a DOS based operating systemAnswerIn Unix and Unix-like systems, a hard link is a directory entry (filename) that points to the file itself. The operating system keeps track of how many hard links point to a file, so when the last hard link to a file is removed, the file is deleted. A symbolic link is a special file that only contains a filename. The file that a symbolic link refers to may not necessarily exist at any given time.
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It isn't protected against all viruses .. see related link.
For Linux and some Unix systems, the /proc system is not on the hard drive.
cp, or "copy", makes an exact duplicate of a file and puts it in the specified location. ln instead makes a "link" to the file. The advantage of using ln is that it saves space on the hard drive, and operations applied to the link will affect the target.