Sed (Stream EDitor) replacement string

sed   -i  's/original/new/g'

Detailed description:

• sed = Stream EDitor (Stream Editor)
• -i = in-place (ie save back to the original file) (write back source is replaced file)

• The command string:

  • s = the substitute command
  • original = a regular expression describing the word to replace (or just the word itself)（被替换）
  • new = the text to replace it with (replace it)
  • g = global (i.e. replace all and not just the first occurrence) （全部替换）

• file.txt = the file name