setting variable with unknown name in bash

Question

I would like to set a variable which name is stored in a file (is an output of a sed executed earlier)

the file would look like:
py1
so setting our variable would be like: set cat file=value
but echoing $py1 gives me nothing.

Is that possible with bash version 2.05?

Answer 1

Use eval:

eval "$(cat file)=value"

Update: The command substitution $(cat file) can be replaced by the equivalent but faster $(< file).

Answer 2

This is the "preferred" way to do it (bash) without using cat or eval

declare $(<file)=value

Answer 3

You'll need to use eval

eval $(cat file)=value