Usage:

$ terraform workspace <subcommand> [options] [args]

$ terraform workspace --help

Usage: terraform workspace

  New, list, show, select and delete Terraform workspaces.

Subcommands:
    delete    Delete a workspace
    list      List Workspaces
    new       Create a new workspace
    select    Select a workspace
    show      Show the name of the current workspace

Example:

$ WS_NAME=foo
$ terraform workspace select $WS_NAME || terraform workspace new $WS_NAME