Awk: extract different columns from many different files

Question

File Example

I have a 3-10 amount of files with:

 - different number of columns
 - same number of rows
 - inconsistent spacing (sometimes o         


        

Answer 1

Assuming each of your files has the same number of rows, here's one way using GNU awk. Run like:

awk -f script.awk file1.txt file2.txt file3.txt file4.txt

Contents of script.awk:

FILENAME == ARGV[1] { one[FNR]=$1 }
FILENAME == ARGV[2] { two[FNR]=$3 }
FILENAME == ARGV[3] { three[FNR]=$7 }
FILENAME == ARGV[4] { four[FNR]=$1 }

END {
    for (i=1; i<=length(one); i++) {
        print one[i], two[i], three[i], four[i]
    }
}

Note:

By default, awk separates columns on whitespace. This includes tab characters and spaces, and any amount of these. This makes awk ideal for files with inconsistent spacing. You can also expand the above code to include more files if you wish.