bash 如何在shell中找到某个字符位置
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How to find certain character position in shell
提问by Mitko Gurbanski
For a given string:
对于给定的字符串：
a="This is test.txt file"
How to find position of the .in a shell environment? It should return 13.
如何.在shell环境中找到的位置？它应该返回13。
回答by anubhava
Using BASH:
使用 BASH：
a="This is test.txt file"
s="${a%%.*}" # remove all text after DOT and store in variable s
echo "$(( ${#s} + 1 ))" # get string length of $s + 1
13
Or using awk:
或使用awk：
awk -F. '{print length()+1}' <<< "$a"
13
回答by vishalknishad
Using C:
使用 C：
#include <stdio.h>
#include <string.h>
int main() {
char a[] = "This is test.txt file";
int i = 0;
while( i < strlen(a) ) {
if( a[i] == '.' ) {
printf("%d", i + 1);
break;
}
i++;
}
return 0;
}
回答by unifex
Clearly this is a duplicated question but all answers are not on both pages.
显然，这是一个重复的问题，但并非所有答案都在两页上。
Additional useful information can be found at Position of a string within a string using Linux shell script?
其他有用的信息可以在使用 Linux shell 脚本的字符串中的字符串位置找到？
This script will find a single character or a multi-character string. I've modified the code on the other page to fit the question here:
此脚本将查找单个字符或多字符字符串。我已经修改了另一页上的代码以适应这里的问题：
#strindex.sh
A="This is test.txt file"
B=.
strindex() {
X="${1%%*}"
[[ "$X" = "" ]] && echo -1 || echo "$[ ${#X} + 1 ]"
}
strindex "$A" "$B"
#end
This returns 13 as requested.
这将根据请求返回 13。
In the above example I would prefer to define the variables 'A' and 'B' with A="$(cat $1)" and B="$2" so the script can be used on any file and any search string from the command line. Note I also changed the variables to upper case from the other page's example. This is not mandatory but some people think variables in upper case is a nice convention and easier to read and identify.
在上面的例子中，我更愿意用 A="$(cat $1)" 和 B="$2" 定义变量 'A' 和 'B'，这样脚本就可以用于任何文件和命令中的任何搜索字符串线。请注意，我还将其他页面示例中的变量更改为大写。这不是强制性的，但有些人认为大写的变量是一个很好的约定，更容易阅读和识别。
