Fix arcstat.py handling of unsupported options

This change allows the arcstat.py script to handle unsupported options
gracefully and print both error and usage messages when one such option
is provided.

Reviewed-by: Giuseppe Di Natale <guss80@gmail.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: loli10K <ezomori.nozomu@gmail.com>
Closes #7799

diff --git a/cmd/arcstat/arcstat.py b/cmd/arcstat/arcstat.py
index 85c83ccc442b209fa0d5d0c5fa4f4cca38396241..b52a8c29477cb84c0017f4815865e2c6271b0842 100755 (executable)
--- a/cmd/arcstat/arcstat.py
+++ b/cmd/arcstat/arcstat.py
@@ -285,7 +285,7 @@ def init():
             ]
         )
     except getopt.error as msg:
-        sys.stderr.write(msg)
+        sys.stderr.write("Error: %s\n" % str(msg))
         usage()
         opts = None