bash 在bash中使用回车执行字符串比较
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Performing string comparison with carriage return in bash
提问by Zhro
Why does the following code fail in bash? Note, I am trying to perform a more complex comparison such as "somestring\r"; this is just a simplified example.
为什么以下代码在 bash 中失败？请注意，我正在尝试执行更复杂的比较，例如 "somestring\r"; 这只是一个简化的例子。
I can confirm that the carriage return "ascii 13" is getting into the script. But I cannot compare against it with a regular string comparison.
我可以确认回车符“ascii 13”正在进入脚本。但是我无法将它与常规字符串比较进行比较。
The expected result is "1" for a positive match.
正匹配的预期结果是“1”。
Command line:
命令行：
echo -e "\r" | ./test.sh
Script:
脚本：
ord() {
printf '%d' "'"
}
read a
echo "1st char: $(ord ${a:0:1})"
left="${a:0:1}"
if [ "$left" = "\r" ]; then
echo 1
fi
exit 0
采纳答案by devnull
The following would illustrate how you can determine if the string contains a carriage return:
下面将说明如何确定字符串是否包含回车：
read a
if [[ $a =~ $'\r' ]]; then
echo 1;
fi
Executing it by saying:
执行它说：
echo -e "something\r" | bash foo
would return
会回来
1
EDIT: If you want to figure whether the last character of a string contains a carriage return, you could say:
编辑：如果您想确定字符串的最后一个字符是否包含回车，您可以说：
if [[ ${a: -1} = $'\r' ]]; then
echo 1;
fi
