CODEWITHSUNDEEP
bashshellcut
ulkar
ulkar

Reputation: 87

Cut and replace bash

I have to process a file with data organized like this

AAAAA:BB:CCC:EEEE:DDDD
FF:III:JJJ:KK:LLL
MMMM:NN:OOO:PP
etc

Columns can have different length but lines always have the same number of columns.

I want to be able to cut a specific column of a given line and change it to the value I want.

For example I'd apply my command and change the file to

AAAAA:BB:XXXX:EEEE:DDDD
FF:III:JJJ:KK:LLL
MMMM:NN:OOO:PP

I know how to select a specific line with sed and then cut the field but I have no idea on how to replace the field with the value I have.

Thanks

Upvotes: 3

Views: 9208

Answers (2)

sampson-chen
sampson-chen

Reputation: 47267

Here's a way to do it with awk:

Going with your example, if you wanted to replace the 3rd field of the 1st line:

awk 'BEGIN{FS=OFS=":"} {if (NR==1) {$3 = "XXXX"}; print}' input_file

Input:

AAAAA:BB:CCC:EEEE:DDDD
FF:III:JJJ:KK:LLL
MMMM:NN:OOO:PP

Output:

AAAAA:BB:XXXX:EEEE:DDDD
FF:III:JJJ:KK:LLL
MMMM:NN:OOO:PP

Explanation:

  • awk: invoke the awk command
  • '...': everything enclosed by single-quotes are instructions to awk
  • BEGIN{FS=OFS=":"}: Use : as delimiters for both input and output. FS stands for Field Separator. OFS stands for Output Field Separator.
  • if (NR==1) {$3 = "XXXX"};: If Number of Records (NR) read so far is 1, then set the 3rd field ($3) to "XXXX".
  • print: print the current line
  • input_file: name of your input file.

If instead what you are trying to accomplish is simply replace all occurrences of CCC with XXXX in your file, simply do:

sed -i 's/CCC/XXXX/g` input_file

Note that this will also replace partial matches, such as ABCCCDD -> ABXXXXDD

Upvotes: 6

potong
potong

Reputation: 58371

This might work for you (GNU sed):

sed -r 's/^(([^:]*:?){2})CCC/\1XXXX/' file

or 

awk -F: -vOFS=: '$3=="CCC"{$3="XXXX"};1' file

Upvotes: 1

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