general

Understand Machine

top see mem usage

du -sh to see size of dir

du -h --max-depth=1 | sort -hr to see size of dirs/files in folder

tail get end of file, tail -f to open buffer and show end of file updating

head get start of file

Pbcopy

pbcopy < atom.sh

Word Count(wc)

wc -l [filename]

Find number of lines in a directory

find . -name '*' | xargs cat | wc -l

XARGS

cat [filename] | xargs wc -l => wc -l [filename]

xargs [utility] [utility args]

reads from the standard input ​ and executes utility