MacOS

Time Machine

• To show hidden files

defaults write com.apple.finder AppleShowAllFiles TRUE
killall Finder

• To allow Remote disc feature on non-Air Macs

defaults write com.apple.NetworkBrowser EnableODiskBrowsing -bool true
defaults write com.apple.NetworkBrowser ODSSupported -bool true
sudo reboot

• To change Computer name

scutil --set HostName servername.example.com
scutil --set ComputerName servername
scutil --set LocalHostName servername

• To check what is preventing MacBook to go to sleep

pmset -g assertions

In my case it was a stuck job in a printer queue:

Listed by owning process:
  pid 19: [0x0000012c00000013] PreventSystemSleep named: "org.cups.cupsd"

• To make Ctrl_L & ALT_L combination work in X11

cat > ~/.Xmodmap  << EOF
clear Mod1
keycode 66 = Alt_L
keycode 69 = Alt_R
add Mod1 = Alt_L
add Mod1 = Alt_R
EOF