如何在bash中显示和刷新多行

Question

我正在编写安装脚本,并希望显示脚本的进展状态.

例:

var1="pending"
var2="pending"
var3="pending"

print_status () {
echo "Status of Item 1 is: "$var1""
echo "Status of Item 2 is: "$var2""
echo "Status of Item 3 is: "$var3""
}

code that does something and then refreshes the
output above as the status of each variable changes.

Answer 1

这段代码应该给你一个想法:

while :; do
    echo "$RANDOM"
    echo "$RANDOM"
    echo "$RANDOM"
    sleep 0.2
    tput cuu1 # move cursor up by one line
    tput el # clear the line
    tput cuu1
    tput el
    tput cuu1
    tput el
done

用于man tput获取更多信息.要查看使用的功能列表man terminfo

Answer 2

我找到了现有答案中未提及的另一种解决方案。我正在为 openwrt 开发程序，tput默认情况下不可用。下面的解决方案受到Missing tput和Cursor Movement 的启发。

- Position the Cursor:
  \033[<L>;<C>H
     Or
  \033[<L>;<C>f
  puts the cursor at line L and column C.
- Move the cursor up N lines:
  \033[<N>A
- Move the cursor down N lines:
  \033[<N>B
- Move the cursor forward N columns:
  \033[<N>C
- Move the cursor backward N columns:
  \033[<N>D

- Clear the screen, move to (0,0):
  \033[2J
- Erase to end of line:
  \033[K

- Save cursor position:
  \033[s
- Restore cursor position:
  \033[u

至于你的问题：

var1="pending"
var2="pending"
var3="pending"

print_status () {
    # add \033[K to truncate this line
    echo "Status of Item 1 is: "$var1"\033[K"
    echo "Status of Item 2 is: "$var2"\033[K"
    echo "Status of Item 3 is: "$var3"\033[K"
}

while true; do 
    print_status
    sleep 1
    printf "\033[3A"    # Move cursor up by three line
done

Answer 3

这并不能完全解决您的问题，但可能会有所帮助；要在执行每个命令后打印状态，请像这样修改 PS1：

PS1='$PS1 $( print_status )'