2010-07-22

• [備忘] 重新改用 root 身份執行的 shell script

  [ "`id -u`" != "0" ] && exec sudo su -c "$0" "$@"
  

• [備忘] 讓標準輸出(STDOUT)與標準錯誤(STDERR)導入到 log 檔的 bash script 寫法

  #! /bin/bash
  
  TARGET="target-file"
  
  # file descriptor 4 prints to STDOUT and to TARGET
  exec 4> >(while read a; do echo $a; echo $a >>$TARGET; done)
  
  # now STDOUT is redirected
  exec >&4
  # now STDERR is redirected
  exec 2>&4
  # generate output to STDOUT, it will also write to $TARGET
  date
  echo "Date sent to fd4."
  # generate output to STDERR, it will also write to $TARGET
  abc