Update usage to be letsencrypt-auto or letsencrypt, as appropriate

letsencrypt/cli.py

@@ -44,6 +44,11 @@ from letsencrypt.plugins import disco as plugins_disco
 
 logger = logging.getLogger(__name__)
 
+# For help strings, figure out how the user ran us.
+# When invoked from letsencrypt-auto, sys.argv[0] is something like:
+# /home/user/.local/share/letsencrypt/bin/letsencrypt"
+fragment = os.path.join(".local", "share", "letsencrypt")
+cli_command = "letsencrypt-auto" if fragment in sys.argv[0] else "letsencrypt"
 
 # Argparse's help formatting has a lot of unhelpful peculiarities, so we want
 # to replace as much of it as we can...
@@ -51,7 +56,7 @@ logger = logging.getLogger(__name__)
 # This is the stub to include in help generated by argparse
 
 SHORT_USAGE = """
-  letsencrypt [SUBCOMMAND] [options] [-d domain] [-d domain] ...
+  {0} [SUBCOMMAND] [options] [-d domain] [-d domain] ...
 
 The Let's Encrypt agent can obtain and install HTTPS/TLS/SSL certificates.  By
 default, it will attempt to use a webserver both for obtaining and installing
@@ -65,7 +70,7 @@ the cert. Major SUBCOMMANDS are:
   config_changes       Show changes made to server config during installation
   plugins              Display information about installed plugins
 
-"""
+""".format(cli_command)
 
 # This is the short help for letsencrypt --help, where we disable argparse
 # altogether