Adding numbers from the result of a grep

Question

I run the following command:

grep -o "[0-9] errors" verification_report_3.txt | awk '{print $1}'

and I get the following result:

1
4
0
8

I'd like to add each of the numbers up to a running count variable. Is there a magic one liner someone can help me build?

Answer 1

grep -o "[0-9] errors" verification_report_3.txt | awk '{ SUM += $1} END { print SUM }'

That doesn't print the list but does print the sum. If you want both the list and the sum, you can do:

grep -o "[0-9] errors" verification_report_3.txt | awk '{ SUM += $1; print $1} END { print SUM }'

Answer 2

This can all be done in awk as well:

awk '"[0-9]+ errors" {sum += $1}; END {print sum}' verification_report_3.txt

Answer 3

You appear to be using GNU system, so if Perl regular expressions support is available, you could write something like this:

grep -Po '[0-9]+(?=\s+errors)' infile | 
  paste -sd+ | 
    bc

P.S. I modified the regular expression (added the + quantifier) to allow numbers > 9.

P.S. Alternatively, awk is sufficient (assuming GNU awk):

awk 'END { print s }
/[0-9]+[[:space:]]+errors/ { 
  s += $1 
  }' infile

Answer 4

Try piping the output from your grep into

awk 'BEGIN {total=0;}{total+=$1;}END {print "Total: ",total}'

Answer 5

I use this:

$ echo $(cat file | sed 's/$/+/') 0 | bc

It isn't efficient for large lists, but for most of my use cases it is fine. I usually use a shell function to automate the process so that I only have to provide a file name:

## cheezy summation
##   call from .bashrc
##
getsum () { echo $(cat $1 | sed 's/$/+/') 0 | bc; }
gethsum () { echo $(cat $1 | sed 's/[gG]/*1000M/' | sed 's/[mM]/*1000K/' | sed 's/[kK]/*1000/' | sed 's/$/+/') 0 | bc; }
gethexsum () { echo ibase=16 $(cat $1 | sed 's/$/+/') 0 | bc; }

You can always substitute the end-of-line marker for a specific element separator or character class if your data is delimited in another fashion.

Answer 6

10 years later I think using awk is the easiest.

grep "[0-9] errors" | awk 'BEGIN {FS="\n"} {sum += $1} END {print sum}

• BEGIN {FS="="}: This sets the field separator to\n before processing any input lines. By default, awk uses whitespace as the field separator, but this changes it to \n.
• END {print sum}: After all lines processed prints result of {sum += $1} (add value before \n to sum)

You may want to use a different field separator.