linux - How can I look up a variable by name with #!/bin/sh (POSIX sh)?

Question

f1="filename1";
i=1;
c=f$i
echo $c

What shell command should I use so that echo $c returns "filename1" as the output?

Answer 1

Use variable indirection.

#!/bin/bash
f1="filename1";
i=1;
c=f$i
echo ${!c}  

It works in bash ( GNU bash, version 4.1.2(1)-release ). I have not tried in other shells.