head and grep simultaneously

Question

Is there a unix one liner to do this?

head -n 3 test.txt > out_dir/test.head.txt
grep hello test.txt > out_dir/test.tmp.txt
cat out_dir/test.head.txt out_dir/test.tmp.txt > out_dir/test.hello.txt
rm out_dir/test.head.txt out_dir/test.tmp.txt

I.e., I want to get the header and some grep lines from a given file, simultaneously.

Answer 1

Use awk:

awk 'NR<=3 || /hello/' test.txt > out_dir/test.hello.txt

Answer 2

You can say:

{ head -n 3 test.txt ; grep hello test.txt ; } > out_dir/test.hello.txt

Answer 3

Try using sed

sed -n '1,3p; /hello/p' test.txt > out_dir/test.hello.txt