string 如何在shell中获取字符串的最后一个字符？
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How to get the last character of a string in a shell?
提问by thinker3
I have written the following lines to get the last character of a string:
我写了以下几行来获取字符串的最后一个字符：
str=
i=$((${#str}-1))
echo ${str:$i:1}
It works for abcd/:
它适用于abcd/：
$ bash last_ch.sh abcd/
/
It does not work for abcd*:
它不适用于abcd*：
$ bash last_ch.sh abcd*
array.sh assign.sh date.sh dict.sh full_path.sh last_ch.sh
It lists the files in the current folder.
它列出了当前文件夹中的文件。
采纳答案by perreal
That's one of the reasons why you need to quote your variables:
这就是您需要引用变量的原因之一：
echo "${str:$i:1}"
Otherwise, bash expands the variable and in this case does globbing before printing out. It is also better to quote the parameter to the script (in case you have a matching filename):
否则，bash 会扩展变量，并且在这种情况下会在打印之前进行 globbing。最好将参数引用到脚本中（以防您有匹配的文件名）：
sh lash_ch.sh 'abcde*'
Also see the order of expansions in the bash reference manual. Variables are expanded before the filename expansion.
另请参阅bash 参考手册中的扩展顺序。在文件名扩展之前扩展变量。
To get the last character you should just use -1as the index since the negative indices count from the end of the string:
要获取最后一个字符，您应该将其-1用作索引，因为负索引从字符串的末尾开始计数：
echo "${str: -1}"
The space after the colon (:) is required.
冒号 ( :)后的空格是必需的。
This approach will not work without the space.
如果没有空间，这种方法将不起作用。
回答by quickshiftin
Per @perreal, quoting variables is important, but because I read this post like 5 times before finding a simpler approach to the question at hand in the comments...
根据@perreal，引用变量很重要，但是因为在评论中找到解决手头问题的更简单方法之前，我阅读了这篇文章 5 次......
str='abcd/'
echo "${str: -1}"
Output: /
输出： /
str='abcd*'
echo "${str: -1}"
Output: *
输出： *
Thanks to everyone who participated in this above; I've appropriately added +1's throughout the thread!
感谢所有参与上述活动的人；我在整个线程中适当地添加了 +1！
回答by user5394399
I know this is a very old thread, but no one mentioned which to me is the cleanest answer:
我知道这是一个非常古老的线程，但没有人提到哪个对我来说是最干净的答案：
echo -n $str | tail -c 1
Note the -nis just so the echo doesn't include a newline at the end.
请注意，这-n只是使 echo 在末尾不包含换行符。
回答by mark_infinite
Try:
尝试：
"${str:$((${#str}-1)):1}"
For e.g.:
例如：
someone@mypc:~$ str="A random string*"; echo "$str"
A random string*
someone@mypc:~$ echo "${str:$((${#str}-1)):1}"
*
someone@mypc:~$ echo "${str:$((${#str}-2)):1}"
g
回答by phep
Every answer so far implies the word "shell" in the question equates to Bash.
到目前为止，每个答案都暗示问题中的“shell”一词等同于 Bash。
This is how one could do that in a standard Bourne shell:
这是在标准的 Bourne shell 中如何做到这一点的：
printf $str | tail -c 1
回答by mr.baby123
another solution using awk script:
使用 awk 脚本的另一个解决方案：
last 1 char:
最后 1 个字符：
echo $str | awk '{print substr(echo $str | awk '{print substr(${str:${#str}-1:1}
,length-5,5)}'
,length,1)}'
last 5 chars:
最后 5 个字符：
echo "${str:${#str}-1:1}"
回答by Eduardo Cuomo
Single line:
单线：
echo $str | cut -c $((${#str}))
Now:
现在：
##代码##回答by pradeep
is a good approach
是个好方法
