usdt.py: improve error messags for enable_probe()

src/python/bcc/usdt.py

@@ -149,20 +149,18 @@ def enable_probe(self, probe, fn_name):
  if lib.bcc_usdt_enable_probe(self.context, probe.encode('ascii'),
  fn_name.encode('ascii')) != 0:
  raise USDTException(
- ("failed to enable probe '%s'; a possible cause " +
- "can be that the probe requires a pid to enable") %
- probe
- )
+"""Failed to enable USDT probe '%s':
+the specified pid might not contain the given language's runtime,
+or the runtime was not built with the required USDT probes. Look
+for a configure flag similar to --with-dtrace or --enable-dtrace.
+To check which probes are present in the process, use the tplist tool.
+""" % probe)
 
  def enable_probe_or_bail(self, probe, fn_name):
- if lib.bcc_usdt_enable_probe(self.context, probe.encode('ascii'),
- fn_name.encode('ascii')) != 0:
- print(
-"""Error attaching USDT probes: the specified pid might not contain the
-given language's runtime, or the runtime was not built with the required
-USDT probes. Look for a configure flag similar to --with-dtrace or
---enable-dtrace. To check which probes are present in the process, use the
-tplist tool.""")
+ try:
+ self.enable_probe(probe, fn_name)
+ except USDTException as e:
+ print(e)
  sys.exit(1)
 
  def get_context(self):