在 bash 中修剪尾部和前导斜杠 - 加入参数替换？
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Trim trailing and leading slash in bash - joining param substitutions?
提问by whitfin
I'm trying to trim a possible /from the start and end of a string in bash.
我正在尝试/从 bash 中的字符串的开头和结尾修剪一个可能的值。
I can accomplish this via the following:
我可以通过以下方式完成此操作：
string="/this is my string/"
string=${string%/}
string=${string#/}
echo $string # "this is my string"
however, I would like to know if there's a way to join those two lines (2 + 3) to replace both at once. Is there a way to join the substitution, or is that the best I'm going to get?
但是，我想知道是否有办法加入这两行 (2 + 3) 以同时替换这两行。有没有办法加入替换，或者这是我将要得到的最好的方法？
Thanks in advance.
提前致谢。
采纳答案by konsolebox
Unfortunately there's no way to do that. However if you're sure that your string begins in / and ends in / you can trim it by ${P:M:N}format:
不幸的是，没有办法做到这一点。但是，如果您确定字符串以 / 开头并以 / 结尾，则可以按${P:M:N}格式修剪它：
string='/this is my string/'
string=${string:1:(-1)}
Adding a check could also help but it's still two statements:
添加检查也可能有所帮助，但它仍然是两个语句：
[[ $string == /*/ ]] && string=${string:1:(-1)}
Note: Solution is only available starting Bash 4.2.
注意：解决方案仅从 Bash 4.2 开始可用。
回答by Stormcloud
Comming to this very late... You can use bash variable substitution can remove a leading OR trailing optional slash, but it can't do both at the same time. If we execute:
来到这个很晚......您可以使用bash变量替换可以删除前导或尾随可选斜杠，但它不能同时进行。如果我们执行：
VAR1=/one/two/
VAR2=one/two
echo ${VAR1} ${VAR2}
echo ${VAR1#/} ${VAR2#/}
echo ${VAR1%/} ${VAR%/}
then we get:
然后我们得到：
/one/two/ one/two # No change
one/two/ one/two # No leading slashes
/one/two /one/two # No trailing slashes
As we can see slashes inside the variables remain unaltered
正如我们所看到的，变量内的斜线保持不变
You can combine them using an intermediate variable as:
您可以使用中间变量将它们组合为：
VAR3=${VAR1#/} # Remove optional leading slash
VAR3=${VAR3%/} # Remove optional trailing slash
echo ${VAR3}
回答by Pankrates
If you are willing to use sedyou could do:
如果你愿意使用，sed你可以这样做：
string="/this is my string/"
echo $string | sed 's/^\/\(.*\)\/$//g'
This assumes the slashes are at the beginning and/or end of the string
这假设斜杠位于字符串的开头和/或结尾
回答by iruvar
If your /s are always at the start and end
如果你的/s 总是在开始和结束
echo "${string//\/}"
this is my string
If not
如果不
string="/this is /my string/"
IFS=/ read -ra x <<<"$string"
(IFS=/; printf '%s\n' "${x[*]:1:${#x[*]}-1}")
this is /my string
Or
或者
echo "$(IFS=/; set -- $string; printf '%s\n' "${*:2:$#-1}")"
this is /my string
回答by mklement0
Another pure bashsolution (v3.2 or above), using =~for regex matching and the special $BASH_REMATCHarray variable to reference capture group results.
另一个纯bash解决方案（v3.2 或更高版本），=~用于正则表达式匹配和特殊$BASH_REMATCH数组变量来引用捕获组结果。
string='/this is my string/'
[[ $string =~ ^/(.*)/$ ]] && string=${BASH_REMATCH[1]}
$stringis left untouched if its value is not enclosed in /.
$string如果其值未包含在 中，则保持不变/。
回答by rishi
#!/bin/bash
truncate_leadingSlash()
{
local string=""
local len=${#string}
while [[ "${string:$(expr $len - 1)}" == "/" ]]
do
string=${string:0:$(expr $len - 1)}
len=${#string}
done
echo $string
}
truncate_leadingSlash "Autobiography/Of/Yogi//////"
Output: "Autobiography/Of/Yogi"
输出：“自传/Of/Yogi”
