The-Unix-Shell-Teaching-Notes

4.3 Appending Data

We have already met the head command, which prints lines from the start of a file. tail is similar, but prints lines from the end of a file instead.

Consider the file shell-lesson-data/data/animals.txt. After these commands, select the answer that corresponds to the file animals-subset.txt:

$ head -n 3 animals.txt > animals-subset.txt
$ tail -n 2 animals.txt >> animals-subset.txt

1. The first three lines of animals.txt
2. The last two lines of animals.txt
3. The first three lines and the last two lines of animals.txt
4. The second and third lines of animals.txt

Solution

Option 3 is correct. For option 1 to be correct we would only run the head command. For option 2 to be correct we would only run the tail command. For option 4 to be correct we would have to pipe the output of head into tail -n 2 by doing head -n 3 animals.txt | tail -n 2 > animals-subset.txt

Episode 4 Piping commands together