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Improve test_monitor_tshark.sh output and error handling 

- Add progress messages and debug output
- Show tshark warnings/errors
- Always display counters even if no packets captured
- Better handling of empty output
- Show sample packets when available
- Add DLT check before capture

Co-authored-by: Cursor <cursoragent@cursor.com>
This commit is contained in:
Robert McMahon 2026-02-13 13:51:54 -08:00
parent a98a255147
commit cc180b7868
1 changed files with 42 additions and 8 deletions
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50
test_monitor_tshark.sh
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@ -80,11 +80,32 @@ iw dev "$INTERFACE" info | grep -E "(type|channel)" || echo "Could not verify"
# Check DLT with tshark (capture for 1 second)
echo ""
echo "Checking Data Link Type (1 second test capture)..."
TEST_OUTPUT=$(timeout 1 tshark -i "$INTERFACE" -T fields -e frame.number -e radiotap.present 2>&1)
# First check if we can open the interface
DLT_CHECK=$(tshark -i "$INTERFACE" -T fields -e frame.number -c 0 2>&1 | head -1)
if echo "$DLT_CHECK" | grep -q "Running as"; then
echo "$DLT_CHECK"
fi
# Use -c to limit packets and add immediate output, redirect stderr to see warnings
# Use a shorter timeout and limit packets to avoid hanging
TEST_OUTPUT=$(timeout 2 tshark -i "$INTERFACE" -c 100 -T fields -e frame.number -e radiotap.present 2>&1 || echo "")
TEST_EXIT_CODE=$?
# Show any warnings/errors from tshark
echo "$TEST_OUTPUT" | grep -E "(Running as|tshark:|Warning|Error)" || true
# Count packets (lines starting with a number)
PACKET_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
PLCP_COUNT=$(echo "$TEST_OUTPUT" | grep -E '^[0-9]+.*[0-9]' | wc -l || echo "0")
echo "$TEST_OUTPUT" | tail -5 || true
echo "Captured $PACKET_COUNT packet(s) in 1 second"
# Count lines with both frame.number and radiotap.present (non-empty second field)
PLCP_COUNT=$(echo "$TEST_OUTPUT" | awk -F'\t' 'NF >= 2 && $1 != "" && $2 != "" && $2 != "0" && $2 != "-" {count++} END {print count+0}' || echo "0")
# Show sample output
if [ "$PACKET_COUNT" -gt 0 ]; then
echo "Sample packets:"
echo "$TEST_OUTPUT" | grep -E '^[0-9]+' | head -3
fi
echo "Captured $PACKET_COUNT packet(s) in test capture"
if [ "$PLCP_COUNT" -gt 0 ]; then
echo "PLCP headers: $PLCP_COUNT (radiotap present)"
else
@ -97,6 +118,7 @@ echo "Press Ctrl+C to stop early"
echo ""
# Capture for specified duration and count packets
echo "Capturing packets for $DURATION seconds..."
CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -i "$INTERFACE" -n -T fields \
-e frame.number \
-e frame.time \
@ -107,16 +129,28 @@ CAPTURE_OUTPUT=$(timeout "$DURATION" tshark -i "$INTERFACE" -n -T fields \
-e wlan.fc.type_subtype \
-e radiotap.present \
2>&1)
CAPTURE_EXIT_CODE=$?
# Display first 50 lines of output
echo "$CAPTURE_OUTPUT" | head -50
# Show any warnings/errors
echo "$CAPTURE_OUTPUT" | grep -E "(tshark:|Warning|Error)" | head -5 || true
# Count total packets captured
# Display first 50 lines of packet output
PACKET_LINES=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' || true)
if [ -n "$PACKET_LINES" ]; then
echo ""
echo "Sample packets (first 20):"
echo "$PACKET_LINES" | head -20
else
echo ""
echo "(No packets captured)"
fi
# Count total packets captured (lines starting with a number)
FINAL_COUNT=$(echo "$CAPTURE_OUTPUT" | grep -E '^[0-9]+' | wc -l || echo "0")
# Count packets with PLCP headers (radiotap present)
# radiotap.present field is the 8th field (after frame.number, frame.time, wlan.sa, wlan.da, wlan.fc.type, wlan.fc.subtype, wlan.fc.type_subtype)
PLCP_COUNT=$(echo "$CAPTURE_OUTPUT" | awk -F'\t' 'NF >= 8 && $8 != "" && $8 != "0" && $8 != "-" {count++} END {print count+0}' || echo "0")
PLCP_COUNT=$(echo "$CAPTURE_OUTPUT" | awk -F'\t' 'NF >= 8 && $1 != "" && $8 != "" && $8 != "0" && $8 != "-" {count++} END {print count+0}' || echo "0")
echo ""
echo "=== Capture complete ==="