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How do I sum lines of two files with each other? (1 column of data each) in bash

For example,

I have two files:

File1.log:

123
456
789

and

file2.log:

123
456
789

and I would like to sum them quickly?

(My actual files are over a million lines each, but an equal number of lines.)

The output would be:

246
912
1578
+3


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6 answers


Try the following:

paste -d + file1.log file2.log | bc


Output:

246
912
1578
+10


source


awk to the rescue



awk '{getline t < "file2.log"; print $0+t}' file1.log
+3


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With awk, you can:

awk 'FNR==NR{a[FNR]=$1; next} {print $1 + a[FNR]}' file1 file2
246
912
1578
+2


source


I think that paste

and bc

is the best solution here. Just for fun, here's one way to do it with pure bash (adapted from this post on unix.sx):

while read n1 <&3 && read n2 <&4; do
  echo $((n1 + n2))
done 3<file1.log 4<file2.log

Or use the -u fd

c parameter read

(thanks rici):

while read -u3 n1 && read -u4 n2; do
  echo $((n1 + n2))
done 3<file1.log 4<file2.log

Output:

246
912
1578
+1


source


This could be another option

paste file1.log file2.log | awk '{print $1 + $2;}'

#246
#912
#1578
+1


source


Here's a Perl solution:

perl -lne 'BEGIN{open $in1,shift; open $in2,shift} while($n1=<$in1> and $n2=<$in2>){print $n1+$n2}' file1.log file2.log

A more readable (but slightly slower) version:

open my $in1, "<", shift;
open my $in2, "<", shift;
while ( my $n1 = <$in1> and my $n2 = <$in2> ) {
    print $n1 + $n2
    print "\n";
}
close($in1);
close($in2);

Just for kicks, I compared the above and all the other solutions listed here. They all produce the same result.
Input files are lists of integers from 1 to 999999
seq 999999 > file1.log ; seq 999999 > file2.log

Test results (10 runs each):

shell@thor                     0.070/s
paste@cyrus                    0.410/s
awk@anubhava                   0.546/s
perl_5.6.1                     1.06/s
paste@veerendra                1.32/s
perl_5.20 (readable version)   1.37/s
awk@karakfa (awk 3.1.5)        1.44/s
perl_5.20                      1.75/s
0


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