Get password from OS X Keychain shell / bash function

get_password.sh

# Get password from OS X Keychain function
# Replace %ACCOUNT_NAME% with account name of Keychain item
# See `man security` for more info
get_pw () {
  security 2>&1 >/dev/null find-generic-password -ga "%ACCOUNT_NAME%" \
  | sed 's/password: "\(.*\)"/\1/'
}

# Don't store server credentials in plain text!
PASS=$(get_pw)

Use -w rather than -g to eliminate the need for output redirection or sed. (Tested on High Sierra.)