After uninstalling a package I used to do apt-get autoremove to remove other unused dependencies.
I understand that apt (rather than apt-get) is the modern way to manage packages on the command-line - I can uninstall things with apt remove. But then how do I do the autoremove step? Do I still have to do this with apt-get?
I'm using Ubuntu Utopic.
Short answer: you don't.
Long answer: from the man pages:
apt(Advanced Package Tool) is the command-line tool for handling packages. It provides a commandline interface for the package management of the system. See also apt-get(8) and apt-cache(8) for more low-level command options.
apt-getis the command-line tool for handling packages, and may be considered the user's "back-end" to other tools using the APT library. Several "front-end" interfaces exist, such as aptitude(8), synaptic(8) and wajig(1).
So to apt and apt-get are two tools which are part of the APT library. apt can be used to perform some functions and apt-get others. They have some overlap. apt covers all the common options a basic user would need. apt-get contains more low-level functions that a sysadmin would use.
As per the full man page of the apt tool, it does not have a command to auto remove unused package. One has to use apt-get (or possibly another front-end interface).
apt-getwas considered buggy - it initially didn't handle dependencies properly, so people usedaptitude. This then took a swing, andapt-getwas considered the more reliable way to install things, whileaptitudehad bugs in Ubuntu. Apparentlyaptwas started whenapt-getwas in version1.0.0or something. You're right it basically looks like a neater API for the same features asapt-get,apt-cacheanddpkg, but one of the systems guys here at Canonical told meaptwas now considered the better one to use.apt list | headand got the following warning:WARNING: apt does not have a stable CLI interface yet. Use with caution in scripts.