CODEWITHSUNDEEP
bashshellubuntuenvironment-variablesvariable-expansion
Aleix Mariné
Aleix Mariné

Reputation: 320

How to expand a variable that contains a mixture of text and other variables?

I am writing an script and I need to locate the desktop folder of the current user. I want it to be language-independent so I found that on Ubuntu you can find the path of the desktop (independently of the system language) in ~/.config/user-dirs.dirs in the line beginning with the tag XDG_DESKTOP_DIR.

I can capture this information easily using DESK=$(more ~/.config/user-dirs.dirs | grep "XDG_DESKTOP_DIR" | cut -d '"' -f2) and obtain the path of the Desktop, but the problem is that I obtain something like this: $HOME/Desktop and I need to expand the $HOME variable.

I was doing it with eval but I know that is bad coding so I decided to change it.

So basically I am trying to expand the variable that is inside a variable that contains a mixture of text and variables. I would like to have a solution for this that is not hardcoded for the $HOME variable, because this is not the first time that I find this issue.

I already tried ${!DESK}, ${${DESK}} (I can imagine why this is not working), [[ ${escri} ]] and others in combination with echo -e.

I would be super grateful if someone can help me with this issue since I remember that I already had this problem the first time that I wrote the code, that's why I gave up and used the wicked eval.

Upvotes: 0

Views: 109

Answers (1)

Léa Gris
Léa Gris

Reputation: 19545

The most useful way is to source ~/.config/user-dirs.dirs

. ~/.config/user-dirs.dirs

# Variable is now readily available
echo "$XDG_DESKTOP_DIR"

Another way is to use envsubst to expand the environment variables before parsing the file:

desktop_dir="$(
  envsubst < ~/.config/user-dirs.dirs |
   sed -n 's/XDG_DESKTOP_DIR="\(.*\)"/\1/p'
)"

Upvotes: 5

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