UShell is a command-line interface to basically make it easier to do common things in Unreal via command line that would otherwise usually be a headache to invoke UAT or P4 commands, which are long and require you to remember their parameter names. Many programmers at Epic Games use it for quality of life. We’ve made it available to the public to use but it’s offered “as is”, we don’t offer support for it.
UShell has tab completion and wraps many common commands into much shorter and convenient aliases.
If you look at that Readme you linked, you’ll see some examples of how to use it.
.build editor.build game ps4.build program UnrealInsights shipping.cook game ps4.stage game ps4.run editor- .
run game ps4 --trace -- -ExecCmds="Zippy Bungle Rainbow" .run program UnrealInsights shipping.p4 cherrypick 1234567.sln generate.info
You can write .help in the tool to see more help text. All the information about that tool currently available is in that Readme file and from UShell’s own help texts (try writing just .p4 or .build to see what the command does).