#! /usr/bin/bash

test -x /usr/sbin/tcpretrans.bt && TCPRETRANS=/usr/sbin/tcpretrans.bt
test -x /usr/share/bpftrace/tools/tcpretrans.bt && TCPRETRANS=/usr/share/bpftrace/tools/tcpretrans.bt
# https://github.com/brendangregg/perf-tools/blob/master/net/tcpretrans
test -x ./tcpretrans.pl && TCPRETRANS=./tcpretrans.pl

OUT=/tmp/tcpretransmits.log

if [ -z "$TCPRETRANS" ]; then
  echo "It looks like 'bpftrace' is not installed"
else
  date > $OUT
  netstat -s |awk '/segments sen. out$/ { R=$1; } /segments retransmit+ed$/ { printf("%.4f\n", ($1/R)*100); }' >> $OUT
  $TCPRETRANS | tee -a $OUT
  netstat -s |awk '/segments sen. out$/ { R=$1; } /segments retransmit+ed$/ { printf("%.4f\n", ($1/R)*100); }' >> $OUT
fi