字符串在使用 Linux shell 脚本的字符串中的位置？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/5031764/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Position of a string within a string using Linux shell script?
提问by Yazz.com
If I have the text in a shell variable, say $a:
如果我在 shell 变量中有文本，请说$a：
a="The cat sat on the mat"
How can I search for "cat" and return 4 using a Linux shell script, or -1 if not found?
如何使用 Linux shell 脚本搜索“cat”并返回 4，如果未找到则返回 -1？
回答by qbert220
echo $a | grep -bo cat | sed 's/:.*$//'
回答by Nikita Rybak
回答by Cercerilla
You can use grep to get the byte-offset of the matching part of a string:
您可以使用 grep 获取字符串匹配部分的字节偏移量：
echo $str | grep -b -o str
As per your example:
根据您的示例：
[user@host ~]$ echo "The cat sat on the mat" | grep -b -o cat
4:cat
you can pipe that to awk if you just want the first part
如果你只想要第一部分，你可以将它传递给 awk
echo $str | grep -b -o str | awk 'BEGIN {FS=":"}{print }'
回答by glenn Hymanman
With bash
用 bash
a="The cat sat on the mat"
b=cat
strindex() {
x="${1%%*}"
[[ "$x" = "" ]] && echo -1 || echo "${#x}"
}
strindex "$a" "$b" # prints 4
strindex "$a" foo # prints -1
