sed to change string in a file only once

Question

suggest I have a file example as follows:

c
a
b
a
b
d

and I want to change the first occurance of a to e. Then I do this:

sed -i 's/a/e/' example

and all a changed to e.

So is there any way to make sed only replace once within a file?

Thanks.

possible duplicate: http://stackoverflow.com/questions/148451/how-to-use-sed-to-replace-only-the-first-occurrence-in-a-file — Aziz, Nov 10 '11 at 14:48

score 12 · Accepted Answer · answered Nov 10 '11 at 14:51

12

Applying the information from Aziz' duplicate link to your question, I think this will give you the desired result for your case:

sed -i '0,/a/s//e/' example

answered Nov 10 '11 at 14:51

Felix Rabe

4,206
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4

For greater readability, this could be written `sed -i 0,/a/ s/a/e/'` – Eric Wilson Nov 10 '11 at 14:57

score 5 · Answer 2 · answered Dec 23 '11 at 10:30

Applying the information from Aziz' duplicate link to your question, I think this will give you the desired result for your case:
sed -i '0,/a/s//e/' example

Rabe's answer is good. But, adding a space between address range and 's' command makes it more clearer. like this:

sed -i '0,/a/ s//e/' example

And Wilson's version seems redundant.

sed to change string in a file only once

2 Answers2