This is not a homework assignment. I am new to bash and trying to gather some data from our logging.

I am reading lines from a file. All of the lines look like this:

[info] 1 - 12-04 15:33:37.542 : Finished createWalletRandom, total time 9898ms

I need to parse out the milliseconds (which I will get min, max, average). I can get 9898ms and I need to get rid of the ms for the math to work.

Trying this line below, doesn't change anything:


And trying this below, generates an error get_wallet_times.sh: line 23: -2: substring expression < 0:


Here is my code:

while read ONE_LINE;
    echo $ONE_LINE
    RAW_MILLI_SECONDS="$(cut -d' ' -f13 <<<"$ONE_LINE")"
    echo ${MILLI_SECONDS}
done < logfile.txt

This is on macOS, in case its a bash issue specific to mac. Please let me know if there is anything thing else you need.

Thnx Matt

  • Does MILLI_SECONDS=${RAW_MILLI_SECONDS/ms/} work? – AdminBee Dec 5 '19 at 16:32
  • yes it does. thank you. if you will, please make that an answer :) – just_a_programmer Dec 5 '19 at 16:33
  • Maybe there are additional characters (spaces?) after ms so %?? removes two of them. What is the output of echo "${RAW_MILLI_SECONDS}X"? – Kamil Maciorowski Dec 5 '19 at 16:35
  • @KamilMaciorowski I wondered that as well. I used a line echo "|${RAW_MILLI_SECONDS}|" and got back |9898ms|. So I don't think theres anything trailing, unless I did that wrong. – just_a_programmer Dec 5 '19 at 16:39

I'm unsure if there are differences to the MacOS implementation of bash, but you could try RegExp-based string modification as in


which will replace the pattern ms by the empty string.


You can use awk to parse the entire file

awk '
    /ms$/ { ms += $NF }
    END { printf "Total %ld ms from %d record(s)\n", ms, NR }
' <logfile.txt

The first line matches against ms as the last two characters of a line and sums the numeric value of the corresponding field. The END line reports the totals.

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