我有两个shell脚本(Linux，#!/bin/bash(，一个有一些用于查找文本等的通用函数，另一个利用公共函数并做一些"实际"工作。
当检查一个数组变量(test2.shoranges(以测试/查看它是否是一个数组(declare -p oranges 2>/dev/null | grep -q '^declare -a' && printf "$fmt" "oranges is an indexed array"(时，我偶然发现了另一个数组(LINEStest1.sh内部(突然被随机数">污染"的事实。
我不明白为什么会这样。有人有答案吗？ 如果在使用脚本时回显或 printf，则只有将错误传送到 2>/dev/null 并 grep 输出时，它才产生零区别。我已经将脚本削减到最基本的内容来显示问题。 此外，通过将单行代码分开并将每个片段的输出分配给一个变量(见test3.sh(，可以轻松解决此问题，因此我不会停留在脚本编写或进一步的进展上。我一直在试图回答为什么会发生LINES污染。
test1.sh
#!/bin/bash
declare -a LINES
echo "::: DECLARE ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
test2.sh
#!/bin/bash
source ./test1.sh
declare -a oranges=()
echo "::: test2-1 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
declare -p oranges 2>/dev/null
echo "::: test2-2 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
declare -p oranges 2>/dev/null | grep -E -i '^declare -a'
echo "::: test2-3 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
declare -p oranges 2>/dev/null | grep -E -i '^declare -a' && printf "$fmt" "oranges is an indexed array"
echo "::: test2-4 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
declare -p LINES
declare -p oranges 2>/dev/null | grep -E -i '^declare -a' && printf "$fmt" "oranges is an indexed array" || printf "$fmt" "oranges is not an indexed array"
echo "::: test2-5 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
declare -p oranges 2>/dev/null
echo "::: test2-6 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
运行时，将出现以下输出：
::: DECLARE ::: Length of [LINES] is: 0, :::Content of [LINES] is:
::: test2-1 ::: Length of [LINES] is: 0, :::Content of [LINES] is:
declare -a oranges=()
::: test2-2 ::: Length of [LINES] is: 0, :::Content of [LINES] is:
declare -a oranges=()
::: test2-3 ::: Length of [LINES] is: 1, :::Content of [LINES] is: 81
declare -a oranges=()
::: test2-4 ::: Length of [LINES] is: 1, :::Content of [LINES] is: 81
declare -a LINES=([0]="81")
declare -a oranges=()
::: test2-5 ::: Length of [LINES] is: 1, :::Content of [LINES] is: 81
declare -a oranges=()
::: test2-6 ::: Length of [LINES] is: 1, :::Content of [LINES] is: 81
test3.sh - 解决方法
#!/bin/bash
source ./test1.sh
declare -a oranges=()
echo "::: test2-1 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
someResult="$(declare -p oranges 2>/dev/null)"
thePattern="^declare -a"
nextResult=`grep -E -i "$thePattern" <<< "$someResult"` || nextResult=""
if [[ -n "$nextResult" ]]
then
echo "oranges is an indexed array"
else
echo "oranges is NOT an indexed array"
fi
echo "::: test2-2 ::: Length of [LINES] is: ${#LINES[@]}, :::Content of [LINES] is: ${LINES[@]}"
test3.sh 的输出..
$ ./test3.sh
::: DECLARE ::: Length of [LINES] is: 0, :::Content of [LINES] is:
::: test2-1 ::: Length of [LINES] is: 0, :::Content of [LINES] is:
oranges is an indexed array
::: test2-2 ::: Length of [LINES] is: 0, :::Content of [LINES] is:
LINES是一个保留变量，由 shell 填充，其中包含终端窗口中可能适合的行数。使用不同的变量名称(shell 不使用该名称;请参阅 shell 变量(，它将按预期工作。
正如 David C. Rankin 在他的评论中提到的，所有 UPPER-CASE 中的变量通常都保留给 shell，这就是为什么建议使用小写变量名的原因。
如果由于某种原因必须对变量使用名称 LINES，您可以通过以下命令禁用checkwinsize选项作为解决方法; 但这可能会产生副作用，我不能保证它会一直有效。
shopt -u checkwinsize
这可以解释以下行为：
d. 非交互式 shell 现在对 checkwinsize 的设置做出反应 并设置 前台作业退出后的行和列。
与 http://www.softpanorama.org/Scripting/Shellorama/Bash_history/bash43.shtml 相比