How to check if a symlink target matches a specific path?

Question

I'm creating a bash script to check if a symlink target matches a specific path so, in case it doesn't match, script removes the symlink. I've tried with readlink:

#!/bin/env bash

target_path=$HOME/Code/slate/.slate.js

if [ `readlink $HOME/.slate.js` == "$target_path" ]; then
    rm -rf "$HOME/.slate.js"
fi

but it doesn't work:

%source test
test:5: = not found

**readlink $HOME/.slate.js** might not return exactly the same as **$target_path** it might return something like **Code/slate/.slate.js** which is different from $target_path — vahid abdi, Nov 08 '13 at 13:46
`test` is probably not a good name for a shell script, as it's already a shell built-in and a binary in `/bin` (or `/usr/bin`)... — twalberg, Nov 08 '13 at 15:24

score 28 · Accepted Answer · answered Nov 08 '13 at 13:44

28

You should use double quotes as follow when you compare strings (and yes, the output of readlink $HOME/.slate.js is a string):

[ "$(readlink $HOME/.slate.js)" = "$target_path" ]

answered Nov 08 '13 at 13:44

Radu Rădeanu

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score 7 · Answer 2 · edited Feb 08 '17 at 13:25

In case $target_path does not match the link text exactly, you can check that they are, in fact equivalent (regardless of name). But since a hardlink is preferable you might want to check that case, too (see below).

A more generic solution is:

[ "$(readlink $HOME/.slate.js)" -ef "$target_path" ]

Or, as in your example:

target_path=$HOME/Code/slate/.slate.js

if [ "`readlink $HOME/.slate.js`" -ef "$target_path" ]; then
    rm -rf "$HOME/.slate.js"
fi

But that all assumes that your $HOME/.slate.js is a symbolic link. If it is a hard link (which is preferable, when possible), then it is simpler:

 … [ "$HOME/.slate.js" -ef "$target_path" ] …

Maybe something like (check whether it is a symlink, if so, then check that link matches target; otherwise check whether the files same—either a hard link or actually the same file):

 … [ \( -L "$HOME/.slate.js" -a "`readlink $HOME/.slate.js`" -ef "$target_path" \) \
     -o \( "$HOME/.slate.js" -ef "$target_path" \) ] …

You should also check whether the file is, in fact, the same file (and not a hard link), otherwise you will delete the one and only copy.

How to check if a symlink target matches a specific path?

2 Answers2