Properly return WARNING and CRITICAL in check_bandwidth

modules/nagios/files/check_bandwidth

 #!/usr/bin/env python
 
-import re, subprocess, sys
+import os, re, subprocess, sys
 
 def extract_data(type, vnstat_output):
   match = re.search(r"%s\s*([\d\.]*) (.bit/s)" % type, vnstat_output)
   if not match:
     print "Unable to extract values from '%s'" % vnstat_output
     sys.exit(1)
 
   value = float(match.group(1))
   unit = match.group(2)
   return (value, unit)
 
 def calculate_bits(value, unit):
   if unit == "Mbit/s":
     value *= 1000000
   elif unit == "kbit/s":
     value *= 1000
   return int(value)
 
 if __name__ == "__main__":
   if len(sys.argv) != 3:
-    print "Usage: `basename $0` WARN CRIT"
+    script_name = os.path.basename(sys.argv[0])
+    print "Usage: %s WARN CRIT" % script_name
     sys.exit(0)
 
   (warn, crit) = sys.argv[1:3]
   warn = int(sys.argv[1])
   crit = int(sys.argv[2])
 
   vnstat_output = subprocess.check_output(["vnstat", "-tr"])
   (rx, rx_unit) = extract_data("rx", vnstat_output)
   (tx, tx_unit) = extract_data("tx", vnstat_output)
   status = "rx %s %s tx %s %s" % (rx, rx_unit, tx, tx_unit)
 
   rx = calculate_bits(rx, rx_unit)
   tx = calculate_bits(tx, tx_unit)
   perfdata = "rx=%s;%s;%s tx=%s;%s;%s" % (rx, warn, crit, tx, warn, crit)
 
   output = "%s|%s" % (status, perfdata)
 
   if rx >= crit or tx >= crit:
     print "CRITICAL - " + output
     sys.exit(2)
 
   if rx >= warn or tx >= warn:
     print "WARNING - " + output
     sys.exit(1)
 
   print "OK - " + output