sed command to replace first occurrence in file is not working

/tmp/test.txt

Hi foo bar!
This is again foo bar

Use the following sed commando to replace only the first orrouance of the search-string;

sed -e '1 s/foo/linux/; t' -e '1,// s//linux/' /tmp/test.txt

Result:

Hi linux bar!
This is again foo bar

• Terminal output + OSX version

• Terminal output; first foo on 3th line

With any awk following may help:

awk '/foo/ && ++count==1{sub(/foo/,"linux")} 1' Input_file

With GNU sed if one has enough memory in box following may help:

sed -z 's/foo/linux/' Input_file

With awk

awk '!f && sub(/foo/, "linux"){f=1} 1' ip.txt

• !f will be true as uninitialized variables are falsey by default
• sub(/foo/, "linux") will replace first occurrence of foo and returns 1 - thus making f=1 and subsequent !f to be always false
• 1 to print $0