bash: interpret string variable as file name/path
This is part of the rules of ~-expansion. It is clearly stated in the Bash manual that this expansion is not performed when the ~ is quoted.
Workaround 1
Don't quote the ~.
file=~/path/to/fileIf you need to quote the rest of the filename:
file=~/"path with spaces/to/file"(This is perfectly legal in a garden-variety shell.)
Workaround 2
Use $HOME instead of ~.
file="$HOME/path/to/file"BTW: Shell variable types
You seem to be a little confused about the types of shell variables.
Everything is a string.
Repeat until it sinks in: Everything is a string. (Except integers, but they're mostly hacks on top of strings AFAIK. And arrays, but they're arrays of strings.)
This is a shell string: "foo". So is "42". So is 42. So is foo. If you don't need to quote things, it's reasonable not to; who wants to type "ls" "-la" "some/dir"?