====== Insert the same header (file) in a number of files ======

The trick here is to use ''cat'' and pipe to a tmp file which you then rename to something sensible.

<code bash>
for f in chr*txt; do echo $f; cat header.txt $f > tmp; mv tmp $(basename $f .txt).csv; done
</code>

Note that the above assumes the existence of the header in a file (''header.txt'').  Also this will rename each ''.txt'' file to ''.csv''.