I have a text file as shown below. I would like to subtract the numbers in the first column and add a new column with the calculated values(absolute value) to the input files instead of printing the output. How can I do this for multiple files with awk or sed?
46-104 46 3.95073 46-46 46 1.45997 50-50 50 1.51589 52-100 52 4.16567 desired output
46-104 46 3.95073 58 46-46 46 1.45997 0 50-50 50 1.51589 0 52-100 52 4.16567 48 Here's the quick way using awk:
awk '{ split($1,a,"-"); print $0, (a[1]-a[2] >= 0 ? a[1]-a[2] : a[2]-a[1]) | "column -t" }' file Results:
46-104 46 3.95073 58 46-46 46 1.45997 0 50-50 50 1.51589 0 52-100 52 4.16567 48 For multiple files, assuming you only have files of interest in your present working directory:
for i in *; do awk '{ split($1,a,"-"); print $0, (a[1]-a[2] >= 0 ? a[1]-a[2] : a[2]-a[1]) | "column -t" }' "$i" > "$i.temp" && mv "$i.temp" "$i"; done 
awk doesn't include a native means of editing a file in-place. To work around this, you'll need to use mv. Please see the edit I've made. It will work on multiple files and apply the changes. HTH.With awk:
function abs(value) { return (value<0?-value:value); } { split($1, v, "-") print $0, "\t", abs(v[1]-v[2]) } This might work for you (GNU sed and bc):
sed -r 'h;s/(\S+).*/echo \1|bc/e;H;x;s/\n-?/ /' file h copy the line to the hold space (HS)s/(\S+).*/echo \1|bc/e do the maths in the pattern spaceH append a newline and the answer to the original line in the HSx swap PS and HSs/\n-?/ / substitute the newline and any negative symbol with a spaceAlong the same lines using awk:
awk '{split($1,a,"-");b=a[1]-a[2];sub(/-/,"",b);print $0,b}' file 