Text substitution tool like envsubst, but it can escape vars.
$ cargo install renvsubst
Substitutes the values of environment variables.
$ export FOO=foooo
$ echo 'I like $FOO' | renvsubst
I like foooo
It can escape variable name.
$ echo 'I like $FOO, ${FOO}, \$FOO, \${FOO}' | renvsubst
I like foooo, foooo, $FOO, ${FOO}