Mac OSX

• sudo ln /usr/local/* /usr/lib/** , Operation not permitted.
  This is because EI Capitan has a protection mode. Only /usr/local is open permitted to operation. Other folder is in protection. We can
  -- Reboot mac and keep press cmd+r when booting up
  -- Then go to Utilities > Terminal
  -- Type following commands

csrutil disable
reboot

• Show hidden files

defaults write com.apple.finder AppleShowAllFiles YES

killall Finder

then, option + right click, relaunch

• Show command duration

time ls -alr

output

real	0m0.033s
user	0m0.002s
sys	0m0.004s