a single variable acting as multiple parameters in bash?答案

【问题标题】：a single variable acting as multiple parameters in bash?a single variable acting as multiple parameters in bash?
【发布时间】：2022-12-01 20:18:27
【问题描述】：

How to split a single variable into multiple arguments?

In fish shell, one can use

set my_var (echo 'line1
line2
line3' | string split '\n')

./my_command $my_var

this is equivalent to

./my_command line1 line2 line3

so a single variable acting as multiple parameters, how to do that in bash shell?

【问题讨论】：

标签： bash

【解决方案1】：

If arguments are separated by newlines:

#!/bin/bash

my_var='line1
line2
line3'

mapfile -t args <<< "$my_var"
./my_command "${args[@]}"

args is an array name here (it can be any other valid name). "${args[@]}" expands array elements as a list.

【讨论】：

【解决方案2】：

You could try mapfile, something like:

#!/usr/bin/env bash

my_var="line1 line2 line3"

mapfile -t argv <<< "${my_var/ //$'
'}"

./my_command "${argv[@]}"

If the variable has embedded newlines, try

#!/usr/bin/env bash

my_var='line1
line2
line3'

mapfile -t argv <<< "$my_var"

【讨论】：

【解决方案3】：

Of course, many times you don't need an array at all. If you don't need to iterate over the tokens multiple times or compare them to the adjacent ones or etc, just loop directly.

while read -r value; do
    : something with "$value"
done <<____HERE
    first value
    second one
    third goes here
____HERE

【讨论】：