If a given value is in column A, replace the value in column B

Question

Given the following data:

aaa bbb aaa ccc aaa ddd
123 222 aaa aaa bbb ccc

If the value in column 4 is "ccc", I want to replace the value in column 6 on the same line with the word "end" using sed or awk.

Any ideas will be greatly appreciated.

Answer 1

With awk:

awk '$4=="ccc"{ $6="end" }1' file

The 1 at the end just prints the current line and is a shortcut for { print } (see what is the meaning of 1 at the end of awk script).

Answer 2

I don't recommend using sed to perform operations on tabular data, but I offer a GNU sed solution anyway, given the question's tag.

sed -r 's:^(([^ ]* ){3}ccc [^ ]* )[^ ]*(.*)$:\1end\3:' file

I assumed there could be more than 6 columns. If not, then group \3 (.*) isn't needed.

As you see the code isn't that readable and error-prone when written/modified, therefore an awk solution for example is preferable.

Answer 3

#!/usr/bin/python
k=open('filename','r')
for i in k:
    o=i.strip().split(' ')
    if ( o[3] == "ccc" ):
        o[5]="end"
    print " ".join(o)

output

aaa bbb aaa ccc aaa end
123 222 aaa aaa bbb ccc