Script using data/input which contains variable names

Question

So I have a file "Directories.dat" that contains a list of directories for a script to read that runs on multiple machines. Due to this, the list of directories in the file is often defined with variables such as

#Directories.Dat
/home/$USER
$WORKDIR
$APPDIR
...etc

However, when the script runs through the file Directories.dat , $line ends up being set to /home/$USER rather than /home/myuser

#!/bin/bash
#myscript.sh
for line in $(cat Directories.dat) 
do 
SomeCommand $line
done

Should I not use cat? Is eval the only suitable function for doing this? example SomeCommand $(eval echo $line) #DangerZone or are there other methods to read the lines within the Directories.dat file and show the variables as their stored values?

For *environment* variables, there's `envsubst` - see for example [how do I get my code to use the value of the $HOME variable?](https://unix.stackexchange.com/questions/554333/how-do-i-get-my-code-to-use-the-value-of-the-home-variable) — steeldriver, Nov 18 '20 at 20:51
*tears of joy* I think this will work. As long as I have sourced all the appropriate files. oh boy — link, Nov 18 '20 at 21:05

score 0 · Answer 1 · answered Nov 18 '20 at 23:50

0

Moved from the question

#!/bin/bash
source bashrc.sh mysources.sh
#myscript.sh
for line in $(cat Directories.dat) 
do 
SomeCommand $(echo $line | envsubst)
done

answered Nov 18 '20 at 23:50

roaima

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NB. This is not robust code: it will break if any directory name contains a space – roaima Nov 18 '20 at 23:51
... I'd suggest `envsubst < Directories.dat | while IFS= read -r line; do SomeCommand "$line"; done` – steeldriver Nov 19 '20 at 01:23

Script using data/input which contains variable names

1 Answers1