Bash: how to get real path of a symlink?

问题

Is it possible, executing a file symlinked in /usr/local/bin folder, to get the absolute path of original script? Well, .. I know where original file is, and I know it because I am linkging it. But, ... I want this script working, even if I move original source code (and symlink).

#!/bin/bash
echo "my path is ..."

回答1:

readlink is not a standard command, but it's common on Linux and BSD, including OS X, and it's the most straightforward answer to your question. BSD and GNU readlink implementations are different, so read the documentation for the one you have.

If readlink is not available, or you need to write a cross-platform script that isn't bound to a specific implementation:

If the symlink is also a directory, then

cd -P "$symlinkdir"

will get you into the dereferenced directory, so

echo "I am in $(cd -P "$symlinkdir" && pwd)"

will echo the fully dereferenced directory. That said, cd -P dereferences the entire path, so if you have more than one symlink in the same path you can have unexpected results.

If the symlink is to a file, not a directory, you may not need to dereference the link. Most commands follow symlinks harmlessly. If you simply want to check if a file is a link, use test -L.

回答2:

lets assume we have real script or file and symbolic link to it:

$ ls -la
-rwxr-xr-x 1 root    root  0 Mar 20 07:05 realscript.sh
lrwxrwxrwx 1 root    root 10 Mar 20 07:05 symlink -> realscript.sh

And the part of GNU coreutils are few very usefull commands:

$ realpath symlink
/home/test/realscript.sh

see also on original:

realpath realscript.sh
/home/test/realscript.sh

Also very good combination in scripting is to use dirname on saved

$ dirname /home/test/realscript.sh
/home/test

so to wrap it up, you can use in script

echo  $( dirname $(realpath "symlink") )

or to get and store in variable real script home dir:

script_home=$( dirname $(realpath "$0") )
echo Original script home: $script_home

To test everything, we put symlink into /home/test2/, amend some additional things and run/call it from root directory:

/$ /home/test2/symlink
/home/test
Original script home: /home/test
Original script is: /home/test/realscript.sh
Called script is: /home/test2/symlink

Please try to write your self the amended outputs :)

回答3:

if you are working on Linux readlink -f $LINK and on mac you can also use that greadlink -f $LINK

来源：https://stackoverflow.com/questions/29789204/bash-how-to-get-real-path-of-a-symlink

标签

bash

symlink