ln | Dev Cheatsheets

Links shell cheatsheet.

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NAME
     link, ln -- make links

SYNOPSIS
     ln [-Ffhinsv] source_file [link_name]
     ln [-Ffhinsv] source_file ... link_dirname
     link source_file link_name
...

Create

Symbolic link

A one-way pointer:

$ ln -s TARGET DEST

e.g. Create venv in current directory.

$ ln -s ~/.local/virtualenvs/daylio-csv-parser venv

Or another directory.

$ ln ~/.local/virtualenvs/daylio-csv-parser ~/my-project/venv

Hard link

A two-way link. No flags needed. I don’t think I’ve ever had to use this.

$ ln TARGET DEST

Relative symlink

This doesn’t work on macOS with the BSD ln. So I don’t use this.

$ ln -s -r TARGET DEST

e.g.

$ ln -s -r my-target.txt my-dir/my-symlink
$ # Check it.
$ ls -l my-dir
my-symlink -> ../my-target.txt

Note how the reuslt using ../.

Without the -r flag, the created link would be invalid - tThe symlink would point to a file as ./my-target.txt in its own directory rather than one level up.

e.g.

$ ln -s my-target.txt my-dir/my-symlink
$ # Check it.
$ ls -l my-dir
my-symlink -> my-target.txt

Here is a workaround to get the same behavior, without using the -r flag, by using cd.

$ cd my-dir
$ ln -s ../my-target my-dest
$ cd ..
$ # Check it.
$ ls -l my-dir
my-symlink -> ../my-target.txt

Force

You’ll get a warning if the destination already exists, so use the force flag.

$ ln -s -f TARGET DEST

Flags

     -i    Cause ln to write a prompt to standard error if the target file exists.  If the response
           from the standard input begins with the character `y' or `Y', then unlink the target
           file so that the link may occur.  Otherwise, do not attempt the link.  (The -i option
           overrides any previous -f options.)

     -F    If the target file already exists and is a directory, then remove it so that the link
           may occur.  The -F option should be used with either -f or -i options.  If none is spec-
           ified, -f is implied.  The -F option is a no-op unless -s option is specified.``

  -f    If the target file already exists, then unlink it so that the link may occur.  (The -f
           option overrides any previous -i options.)

Examples

Git hooks

See Add symlink in the Git hooks cheatsheet.

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