ls | wc  -l
ls | wc
ls | wc  -l > out
a | b | c
a 1 < a3/1/2/3 | b 1 2 3 | c  -a  -bb  --c-c-c- | >  d.out  d
ls-t >  x wc-l
java rev < a2/rev.1 | java rev > out
cb | grep -v ......................... > a1-from.txt
find | grep -v facts.txt | grep  -v eca | grep  -v video | grep  -v observations | grep -v bb.txt | grep -v readit.txt
find | grep   -v facts.txt |   grep -v eca   | grep -v video | grep -v observations | grep -v bb.txt | grep -v readit.txt > out
cb | cut -f1 -d@ | grep -v ^$ | grep -v whm | grep -v youhao | grep -v What | tr A-Z a-z | sort -u > a1.csv
<   a   b | c
cb | cut -f1 -d@ | grep -v ^$ | grep -v whm | grep -v youhao | grep -v What | tr A-Z a-z | sort | uniq -c | sort -rn | > x wc