awk prepend and append line of file

Question

I want to prepend and append a certain line of a file using awk.

Example:

Say i have a file with 5 lines, i want to awk the 3rd line and put "hello" at the beginning and "goodbye" at the end.

example file.

1. foo
2. foo
3. foo
4. foo
5. foo

output result hello 3. foo goodbye and delete all other lines 1, 2, 4, 5,

Ive tried awk 'NR==3 {print $0" goodbye"}' <file>

this appends the line with goodbye but i cannot figure out how to prepend the line with "hello"

Ive tried BEGIN and END in the command but unsure how to treat NR==3 ?

Desired output should be..

hello 3. foo goodbye

final output result hello 3. foo goodbye and delete all other lines 1, 2, 4, 5,

Answer 1

Could you please try following. To print all lines only 3rd line with additional details.

awk 'FNR==3{print "hello " $0 " goodbye";next} 1' Input_file

OR

awk 'FNR==3{$0="hello " $0 " goodbye"} 1'  Input_file

In case you want to print only 3rd edited line try:

awk 'FNR==3{print "hello " $0 " goodbye"}' Input_file

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In case you want to print only 3rd line with use of BEGIN and END as per your attempt then try following.

awk 'BEGIN{ORS=" ";printf "hello "} FNR==3; END{printf("%s\n","goodbye")}' Input_file