Today I was looking for a way to combine a set of files in one but before appending a given file, the 2 first lines as well as the last line had to be removed. On Stackoverflow I found a couple of answers (see questions 18006581, 12176492 and 5410757) and based on these I decided to use a combination of head and tail. I ended up creating the following shell script:

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#!/bin/bash
touch biblio.yaml
for f in refs/*.yml
do
  tail -n+3 $f | head -n-1 >> biblio.yaml
  echo "\n" >> biblio.yaml
done

Let’s break it down:

• first the Shebang to mention that it is a bash script;
• then touch biblio.yaml creates the file where all other files will be appended;
• a for loop over the set of files in refs that ends by .yml, at each iteration of the loop, $f will be a new file;
• for each file, print the last lines of the files starting with line 3 (tail -n+3), then take the result (|) and print the first lines of it but stop at the line before the last one (head -n-1) then append the result in biblio.yaml (>> biblio.yaml);
• the iteration with the addition of a line break: echo "\n" >> biblio.yaml.