By "commandline tool" do you mean a password encryption program? Implementing your own cryptographic procedures is highly inadvisable (unless you're an expert i

By "commandline tool" do you mean a password encryption program? Implementing your own cryptographic procedures is highly inadvisable (unless you're an expert in the field). If you're not storing particularly sensitive data you should be fine with a homebrew application, otherwise, you probably ought to use something else. Keepass is pretty good security-wise; it is open source and widely used and does not rely on any network connections.