How to interleave lines from two text files

Question

What's the easiest/quickest way to interleave the lines of two (or more) text files? Example:

File 1:

line1.1 line1.2 line1.3 

File 2:

line2.1 line2.2 line2.3 

Interleaved:

line1.1 line2.1 line1.2 line2.2 line1.3 line2.3 

Sure it's easy to write a little Perl script that opens them both and does the task. But I was wondering if it's possible to get away with fewer code, maybe a one-liner using Unix tools?

Answer 1

paste -d '\n' file1 file2