syntax error: invalid arithmetic operator in bash addition

Question

I am getting the error: "line 9: 0.0000: syntax error: invalid arithmetic operator (error token is ".65")":

Please suggest how to fix this

Tried this:

  #!/bin/bash

  IFS=' ' read -r -a pids <<< $(echo $(pgrep nr-softmodem -d ' ') )
  cpu_sum=0.0000;
  mem=0;
  for i in "${pids[@]}";
      do
     cpu=$(top -b -n1 -p "$i" -H | tail -n +8 | awk '{ if ($9 !=0) {sum += $9; count++} } END    {if (count !=0) {avg =sum/count; print avg}}')
 
         cpu_sum=$(echo $((cpu_sum +=cpu ))) 
 done
 echo "$cpu_sum"

Expected output:

56.65

Output seen:

./top_gNB1.sh: line 9: 0.0000: syntax error: invalid arithmetic operator (error token is ".0000")
./top_gNB1.sh: line 9: 56.65: syntax error: invalid arithmetic operator (error token is ".65")
0

There is no need to do $(echo $(( ... ))). It's equivalent to just doing $(( ... )). Also, add a space after the parentheses. — Verpous
– Verpous, Commented Jul 6, 2023 at 12:32

k314159 · Accepted Answer · 2023-07-06 14:02:09Z

1

Bash can only do integer arithmetic, so you get a syntax error when you give it a decimal point.

Instead of:

         cpu_sum=$(echo $((cpu_sum +=cpu )))

Try:

         cpu_sum=$(echo $cpu_sum + $cpu | bc)

answered Jul 6, 2023 at 14:02

k314159

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4 Comments

Anjali Over a year ago

This doesn't work. It gives error: (standard_in) 2: syntax error

k314159 Over a year ago

On which line does it give an error?

tjm3772 Over a year ago

That sounds like $cpu is either empty or contains something other than a number. Maybe try something like xxd <<< "$cpu" to confirm it doesn't have any tricky characters in it before passing it into bc.

k314159 Over a year ago

In your Awk script, you have END {if (count !=0) {avg =sum/count; print avg}} - so if count is 0, it will not print anything and cpu will be set to an empty string.

Ed Morton · Accepted Answer · 2023-07-06 17:01:00Z

0

Try this, untested, letting awk do the artihmetic:

#!/usr/bin/env bash

IFS=' ' read -r -a pids <<< $(echo $(pgrep nr-softmodem -d ' ') )
cpu_sum=0
mem=0
for i in "${pids[@]}"; do
    cpu_sum=$(
        top -b -n1 -p "$i" -H |
        tail -n +8 |
        awk -v cpu_sum="$cpu_sum" '
            $9 { sum += $9; count++ }
            END {
                if ( count ) {
                    avg = sum / count
                }
                print avg + cpu_sum
            }
        '
    )
done
echo "$cpu_sum"

The line IFS=' ' read -r -a pids <<< $(echo $(pgrep nr-softmodem -d ' ') ) could be improved but that's a different question.

answered Jul 6, 2023 at 17:01

Ed Morton

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