cmd/ln

ln is the Linux command for creating a link to a file or folder.

To create a relative link:

ln -r --symbolic <existing file> <link to create>

• Relative links will still work even if the folder containing both files (the original and the link) is moved or copied.
• Note that a link cannot have the same name as a folder in the same directory.
• The error message "ln: failed to create symbolic link '<filename>': File exists" can be maddeningly misleading. It seems to always report the existing file, even when the problem is actually that the second filename (the link-name) already exists. Translation:
  • "'<arg 1>': File exists" (arg 1 should be <existing file>): The link-name is the same as an existing file, possibly a folder.
    • The fact that ln reports the first param instead of the second one seems to be a bug. Yes, the first param is a file that does exist, but that's not the problem.
  • "'<arg 2>': File exists" (arg 2 should be <name for link>): You've got the arguments backwards, and are trying to create a link under the same name as the existing file (to a file which doesn't exist).

another way to think of it

If you're in the folder where you want the link to go:

ln -r --symbolic <relative path>/<name of file/folder> ./<name for link>

If you're in the folder where the existing/real file is:

ln -r --symbolic ./<name of file> <relative path>/<name for link>

Example

I pretty much always get confused as to which is the link and which is the target, so here's an example. You're inside «/git/futilities/human/ff» and you want to create a link called "lib" to the "lib" folder at «/git/futilities/lib»:

ln -r --symbolic ../../lib/ ./lib

Notes

• LINUX: Link all files from one to another directory