Package prog provides the entry point to Elvish. Its subpackages correspond to subprograms of Elvish.
var DeprecationLevel = 15
DeprecationLevel is a global flag that controls which deprecations to show. If its value is X, Elvish shows deprecations that should be shown for version 0.X.
BadUsage returns an error that may be returned by Program.Main, which requests the main program to print out a message, the usage information and exit with 2.
Exit returns an error that may be returned by Program.Main, which requests the main program to exit with the given code. If the exit code is 0, it returns nil.
Run parses command-line flags and runs the first applicable subprogram. It returns the exit status of the program.
Flags keeps command-line flags.