我的 printf 语句被打印在 2 行上，因为我的程序的输出是多行的，但我希望它只打印一次 [重复]答案

【问题标题】：My printf statement is getting printed on 2 lines one below the other as the output of my program is multiline, but I want it to print just once [duplicate]我的 printf 语句被打印在 2 行上，因为我的程序的输出是多行的，但我希望它只打印一次 [重复]
【发布时间】：2021-09-06 06:37:00
【问题描述】：

    #!/bin/bash
for n in 1 2;
    do var=$(bc -l <<< 'scale=100; 4*a(1)')
    my_time=$( (time bc -l <<< 'scale=100; 4*a(1)') 2>&1 >/dev/null)
    echo $var
    echo $my_time       
    printf "Value of PI is :%s\n" $var
    printf "Time calculated is :%s\n" $my_time
done

输出：

real 0m0.005s user 0m0.004s sys 0m0.000s
Value of PI is :3.141592653589793238462643383279502884197169399375105820974944592307\
Value of PI is :8164062862089986280348253421170676
Time calculated is :real
Time calculated is :0m0.005s
Time calculated is :user
Time calculated is :0m0.004s
Time calculated is :sys
Time calculated is :0m0.000s
3.141592653589793238462643383279502884197169399375105820974944592307\ 8164062862089986280348253421170676
real 0m0.004s user 0m0.000s sys 0m0.000s
Value of PI is :3.141592653589793238462643383279502884197169399375105820974944592307\
Value of PI is :8164062862089986280348253421170676
Time calculated is :real
Time calculated is :0m0.004s
Time calculated is :user
Time calculated is :0m0.000s
Time calculated is :sys
Time calculated is :0m0.000s

正如您在此处看到的，“PI 的值是”和“计算的时间是”语句显示在每一行上。请帮忙！

【问题讨论】：

用shellcheck.net检查你的脚本

标签： linux bash shell sh

【解决方案1】：

请在$var 和$my_time 周围加上双引号，这在变量包含换行符时非常有用（LF aka \n）。

#!/bin/bash
for n in 1 2; do
    var=$(bc -l <<< 'scale=100; 4*a(1)')
    my_time=$( (time bc -l <<< 'scale=100; 4*a(1)') 2>&1 >/dev/null)
    echo $var
    echo $my_time       
    printf "Value of PI is :%s\n" "$var"
    printf "Time calculated is :%s\n" "$my_time"
done

如果您只想在一行上显示bc 结果，请在前面添加BC_LINE_LENGTH=0 ：

BC_LINE_LENGTH=0 bc -l <<< 'scale=100; 4*a(1)'

（使用 bc 1.07.1 测试）

【讨论】：