Unix & Linux Stack Exchange is a question and answer site for users of Linux, FreeBSD and other Un*x-like operating systems. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I would like to replace "CC" with "C" and "AA" with A" in a particular column of Tab delimited file (using awk probably).

share|improve this question
My input data file abc.txt has this "20131008","0004","0568","98" I ran this command to replace the text nawk -F, -vOFS=',' '{gsub("0568","0808",$3); print }' abc.txt In the output the delimiter "," is replaced with a space. The output looks like this "20131008" "0004" "0568" "98". Can someone please help with this? I tried to replace the -vOFS but doesnt work. – user3213938 Aug 19 '14 at 1:14
awk -F'\t' -vOFS='\t' '{ gsub("CC", "C", $1) ; gsub("AA", "A", $1) ; print }'

Replace $1 with the column that you wish to modify.

share|improve this answer
In case the delimiter has to be kept, a -vOFS='\t' option may be added. – manatwork Jun 14 '12 at 10:18
@manatwork Good point, added. – Chris Down Jun 14 '12 at 10:20
fantastic! works as per usual!!! – alex Jun 14 '12 at 10:51
Some versions of awk don't have a gsub function. How would you do it then? Can sed be used instead? – rahmu Jun 14 '12 at 13:33
@rahmu - gsub() has been defined by POSIX for over 20 years, so my suggestion would be to get a version of awk that isn't downright awful ;-) – Chris Down Jun 14 '12 at 13:40

If you didn't have access to gsub(), but you do have access to split(), you could just create the equivalent thusly:

Given the input

AA      AA      CC      CC      AA      CC

the following awk script

    OFS = "\t";
    split("1 3 5", Fields);
    split("A C", Replacements);
    for (i in Fields) {
        for (j in Replacements) {
            Replace = Replacements[j];
            sub(Replace Replace, Replace, $Fields[i]);

would produce the desired results for fields 1, 3, and 5:

A       AA      C       CC      A       CC

Even without split() it's possible if you want to hard-code the Fields and Replacements arrays in the BEGIN block.

share|improve this answer

To find and replace in one field use this command:

sed 's/whatyouwanttofind/whatyouwanttoreplace/field#'

i.e. you echo this:

$echo -e "1are,2are,3are,4are\n5are,6are,7are,8are"



and you want to do this

$echo -e "1are,2are,3are,4are\n5are,6are,7are,8are" |  sed 's/are/arrr/2'


share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.