CODEWITHSUNDEEP
bashshell
1cyf1r3
1cyf1r3

Reputation: 53

Replace data on specific column and row

I currently new to shell scripting and i am having an issue in replacing data. I need to replace the data of a specific column and row.

Below is a random database:

test:test1:test2:test3:test4    
example:example1:example2:example3:example4    
sample:sample1:sample2:sample3:sample4

for example, I would like to replace the word "test3" into "changed".. how do i achieve this? i tried several command like

awk -F : 'NR==n{$4=a}1' n="$row" a="$replace" test.txt
sed -i "$row"'s/\S\+/'"$replace"'/4' test.txt

although there is no error when i run those command, it did not replace my data either. anyone can give me some help on this problem..?

Upvotes: 0

Views: 2535

Answers (2)

halfbit
halfbit

Reputation: 3464

Here is an sed one-liner (using in-place editing):

#!/bin/bash

cat > /tmp/file <<EOF
test:test1:test2:test3:test4    
example:example1:example2:example3:example4    
sample:sample1:sample2:sample3:sample4
EOF

row=1
column=4
replace=changed
sed -i "$row"'s/^\(\([^:]*:\)\{'"$(($column - 1))"'\}\)[^:]*/\1'"$replace"'/' /tmp/file

cat /tmp/file

Upvotes: 0

Tom Fenech
Tom Fenech

Reputation: 74595

Your awk version works fine for me with a minor modification:

$ row=1
$ replace=changed
$ awk 'BEGIN{FS=OFS=":"}NR==n{$4=a}1' n="$row" a="$replace" file
test:test1:test2:changed:test4    
example:example1:example2:example3:example4    
sample:sample1:sample2:sample3:sample4

I have defined the Output Field Separator OFS so that lines which are modified still have : between each field. To overwrite the original file, you can just do awk '...' file > tmp && mv tmp file.

Upvotes: 1

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