(standard_in) 1: syntax error when using bc

Question

I have written an .awk which executes some operation on a .tr file and writes the output to a file. The END section of .awk file prints this:

printf("%15.2f\n%15.5f\n%15.2f\n%15.2f\n%15.2f\n%10.2f\n%10.2f\n%10.5f\n", rThroughput, rAverageDelay, nSentPackets, nReceivedPackets, nDropPackets, rPacketDeliveryRatio, rPacketDropRatio,rTime) ;

printf("%15.5f\n%15.5f\n%15.5f\n%15.5f\n%15.0f\n%15.9f\n", total_energy_consumption, avg_energy_per_bit, avg_energy_per_byte, avg_energy_per_packet, total_retransmit,rEnergyEfficiency);

I call this .awk file from a .shfile. After executing the command which runs the .awk file, I iterate over the values generated by the .awk file.

        awk -f Wireless_udp.awk 802_11.tr > "TEMP"

        while read val
        do
            l=$(($l + 1))

            if [ "$l" == "1" ]; then
                thr=$(echo "scale=5; $thr+$val/$iteration_float" | bc)
#               echo -ne "throughput: $val " 
            elif [ "$l" == "2" ]; then
                del=$(echo "scale=5; $del+$val/$iteration_float" | bc)
#               echo -ne "delay: $val " 
            elif [ "$l" == "3" ]; then
                s_packet=$(echo "scale=5; $s_packet+$val/$iteration_float" | bc)
#               echo -ne "send packet: $val " 
            elif [ "$l" == "4" ]; then
                r_packet=$(echo "scale=5; $r_packet+$val/$iteration_float" | bc)
#               echo -ne "received packet: $val " 
            elif [ "$l" == "5" ]; then
                d_packet=$(echo "scale=5; $d_packet+$val/$iteration_float" | bc)
#               echo -ne ;"drop packet: $val " 
            elif [ "$l" == "6" ]; then
                del_ratio=$(echo "scale=5; $del_ratio+$val/$iteration_float" | bc)
#               echo -ne "delivery ratio: $val " 
            elif [ "$l" == "7" ]; then
                dr_ratio=$(echo "scale=5; $dr_ratio+$val/$iteration_float" | bc)
#               echo -ne "drop ratio: $val "
            elif [ "$l" == "8" ]; then
                time=$(echo "scale=5; $time+$val/$iteration_float" | bc)
#               echo -ne "time: $val " 
            elif [ "$l" == "9" ]; then
                t_energy=$(echo "scale=5; $t_energy+$val/$iteration_float" | bc)
#               echo -ne "total_energy: $val "
            elif [ "$l" == "10" ]; then
                energy_bit=$(echo "scale=5; $energy_bit+$val/$iteration_float" | bc)
#               echo -ne "energy_bit: $val "
            elif [ "$l" == "11" ]; then
                energy_byte=$(echo "scale=5; $energy_byte+$val/$iteration_float" | bc)
#               echo -ne "energy_byte: $val " 
            elif [ "$l" == "12" ]; then
                energy_packet=$(echo "scale=5; $energy_packet+$val/$iteration_float" | bc)
#               echo -ne "energy_packet: $val " 
            elif [ "$l" == "13" ]; then
                total_retransmit=$(echo "scale=5; $total_retransmit+$val/$iteration_float" | bc)
#               echo -ne "total_retrnsmit: $val \n"
            elif [ "$l" == "14" ]; then
                energy_efficiency=$(echo "scale=9; $energy_efficiency+$val/$iteration_float" | bc)
                #       echo -ne "energy_efficiency: "
            fi
#           echo "$val"
        done < "TEMP"

Everything was running fine, but when I added the last if-else condition and executed the script, it gave a (standard_in) 1: syntax error

Specifically, I'm taking about this segment of code:

            elif [ "$l" == "14" ]; then
                energy_efficiency=$(echo "scale=9; $energy_efficiency+$val/$iteration_float" | bc)
#               echo -ne "energy_efficiency: "

TEMP file contains:

      197645.74
        0.32776
       25000.00
        7350.00
       17348.00
     29.40
     69.39
  24.99826
      720.13300
        0.00015
        0.00117
        0.09798
              0
    0.001166018

I'm having difficulty why it's giving an error.

Link to full code:

.tcl file which generates the .tr file .awk file: .sh file:

bash --version gives:

GNU bash, version 4.3.48(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2013 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

OS: Ubuntu 16.04 LTS

Is the variable energy_efficiency initialized anywhere? if not, the first time through the loop will have an empty value before the + — steeldriver, Jan 05 '19 at 01:19
Yes, turns out I forgot to initialize the variable. @steeldriver — Robur_131, Jan 05 '19 at 01:24

score 4 · Accepted Answer · answered Jan 05 '19 at 01:34

Your script doesn't appear to initialize the variable energy_efficiency, so the first time around the loop

echo "scale=9; $energy_efficiency+$val/$iteration_float"

produces

scale=9; +197645.74/1.0

which is a syntax error (bc apparently allows unary -, but not unary +)

$ echo "scale=9; +197645.74/1.0" | bc
(standard_in) 1: syntax error

(standard_in) 1: syntax error when using bc

1 Answers1