Shell Programming and Scripting

tom|25|New York
sims|40|London
neyo|18|Moscow

Names|age|city of birth
tom|25|New York
sims|40|London
neyo|18|Moscow

awk 'BEGIN{print "Names|age|city of birth"}1' file

$
$
$ # Check the content of "staff.txt"
$
$ cat staff.txt
tom|25|New York
sims|40|London
neyo|18|Moscow
$
$
$ # Run the command pipeline to add a header
$
$ echo "Names|age|city of birth" | cat - staff.txt > tmp.txt && mv tmp.txt staff.txt
$
$
$ # Now check the content of "staff.txt" again
$
$ cat staff.txt
Names|age|city of birth
tom|25|New York
sims|40|London
neyo|18|Moscow
$
$

 $ ruby -ne '$_="Names|age|city of birth\n#{$_.chomp}\n" if $.==1;print ' file