[PATCH] usertools/telemetry-watcher: fix hang on startup

[Bruce Richardson <bruce.richardson@intel.com>]

Commit cbfdffb1083d ("usertools/telemetry: load aliases from config
directory") added an extra printed output line to startup of the
dpdk-telemetry script when an alias file was loaded. This confuses the
wrapper script dpdk-telemetry-watcher, causing it to hang on startup.
Only print out the message when script is run interactively.

Fixes: cbfdffb1083d ("usertools/telemetry: load aliases from config directory")
Cc: stable@dpdk.org

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 usertools/dpdk-telemetry.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/usertools/dpdk-telemetry.py b/usertools/dpdk-telemetry.py
index e575f269cb..b4dd789143 100755
--- a/usertools/dpdk-telemetry.py
+++ b/usertools/dpdk-telemetry.py
@@ -98,7 +98,9 @@ def load_aliases(alias_path=None):
     except OSError as e:
         print("Warning: failed to read {}: {}".format(alias_path, e), file=sys.stderr)
 
-    print("Loaded {} aliases from {}".format(len(aliases), alias_path))
+    # only print this informational message in interactive mode
+    if os.isatty(sys.stdin.fileno()):
+        print("Loaded {} aliases from {}".format(len(aliases), alias_path))
     return aliases
 
 
-- 
2.53.0