How to use zypper in bash scripts for someone coming from apt-get?

In general, you should use --non-interactive mode, in shortcut -n, when running zypper non-interactively:

zypper -n install curl

That might seem confusing for someone coming from apt-get install -y curl. Some zypper sub-commands also support a command-specific -y/--no-confirm option as an alias for -n/--non-interactive, but not all sub-commands do. As the install command does implement that, this command is equivalent to the above:

zypper install -y curl

Note that the -y must come after install, while the global -n option comes before the subcommand (zypper install -n means something different; read the man page for that).

[Edit] The section below is no longer accurate, but is retained for historical reference. Current zypper supports the --gpg-auto-import-keys option to automatically import and trust the gpg keys associated with a new repository.

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According to documentation there's no way how to accept a GPG key without interactive mode:

a new key can be trusted or imported in the interactive mode only

Even with --no-gpgp-checks the GPG key will be rejected.

A workaround for scripts is to use pipe and echo:

zypper addrepo http://repo.example.org my_name | echo 'a'

You have the --non-interactive option. From the man page:

Switches  to  non-interactive  mode. 
In this mode zypper doesn't ask user to type answers to various prompts, but uses default answers automatically. 
The  behaviour of this option is somewhat different than that of options like '--yes', since zypper can answer different answers to different questions. 
The answers  also  depend on other options like '--no-gpg-checks'.

There is no real correspondense to apt-get's autoremove. The closest is the --clean-deps option of the remove command, which cleans dependencies right away (but not afterwards).

That is a sample

zypper --non-interactive --quiet addrepo --refresh -p 90 http://packman.inode.at/suse/openSUSE_Leap_15.0/ 'packman'
zypper --gpg-auto-import-keys refresh
zypper --non-interactive dist-upgrade --allow-vendor-change --from packman
zypper --non-interactive install vlc vlc-codecs

Of course you can include more options like --auto-agree-with-licenses but remember that makes difference if its before or after install