Question: Suppose I have a text file with the following format 

```
@ATDGGSGDTSG
NTCCCCC
+
@nddhdhnadn
@ATDGGSGDTSG
NTCCCCC
+
nddhdhnadn

```

Now its a repeating pattern of "4" lines and I every time want to print only the 2nd line i.e. the line after the line starting with "@" i.e 2nd line..6th line..etc.

How can I do it?

Answer: 
```
perl -ne 'print if $b and !/^@/; $b=/^@/' file

```
```
awk '/^\@/{getline;print}' file

```