I commonly work with text files of ~20 Gb size and I find myself counting the number of lines in a given file very often.
The way I do it now it\'s just cat fn
cat fn
find -type f -name "filepattern_2015_07_*.txt" -exec ls -1 {} \; | cat | awk '//{ print $0 , system("cat " $0 "|" "wc -l")}'
Output: