Bash循环命令通过包含空格的列表 [英] Bash loop command through list containing spaces

问题描述

我有一个脚本，其中包含使用同一列表的多个循环命令.看起来像这样:

I have a script with multiple loop commands using the same list. It looks like this:

# List of applications
read -r -d '' Applications << EndOfList
/Applications/App.app
/Applications/App2.app
/Applications/App3.app
/Applications/Another App.app
EndOfList

for file in $Applications
do
    if [ -e "$file" ]; then
        echo ""$file" found"
    fi;
done

exit 1

除了列表中的第四个应用程序外，这似乎可以正常工作，因为应用程序名称中有一个空格.如果我在调试模式下运行脚本，则输出为:

This seems to work fine except for the fourth application in the list, because there's a space in the application name. If I run the script in debug mode, this is the output:

+ read -r -d '' Applications
+ for file in '$Applications'
+ '[' -e /Applications/App.app ']'
+ for file in '$Applications'
+ '[' -e /Applications/App2.app ']'
+ for file in '$Applications'
+ '[' -e /Applications/App3.app ']'
+ for file in '$Applications'
+ '[' -e /Applications/Another ']'
+ for file in '$Applications'
+ '[' -e App.app ']'
+ exit 1

我尝试用反斜杠转义，引用它和其他多种方式，但是我无法使其正常工作.

I've tried escaping with a backslash, quoting it and multiple other ways but I could not get it to work.

推荐答案

在读取和使用BASH数组而不是一个简单的变量来保存时，应将 IFS 设置为 \ n 所有以换行符分隔的条目:

You should set IFS as \n while reading and use BASH array rather a simple variable to hold all the entries delimited by newlines:

#!/bin/bash 

IFS=$'\n' read -r -d '' -a Applications <<'EndOfList'
/Applications/App.app
/Applications/App2.app
/Applications/App3.app
/Applications/Another App.app
EndOfList

for file in "${Applications[@]}"
do
    if [[ -e "$file" ]]; then
        echo "$file found"
    fi;
done

PS::如果您具有BASH 4+版本，请使用 mapfile :

PS: If you have BASH 4+ version then use mapfile:

mapfile -t Applications <<'EndOfList'
/Applications/App.app
/Applications/App2.app
/Applications/App3.app
/Applications/Another App.app
EndOfList

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