shell中有没有方法来忽略转义字符？ [英] Is there a method in shell to ignore escape characters?

问题描述

在C＃中，有一个逐字字符串，以便

  string c =hello \t world; // hello world 
 string d = @hello \t world; // hello \t world 
  

我是shell脚本的新手，shell中是否有类似的方法？

由于我有很多文件夹，名称如服装与配饰>服装>活动服装，我想知道是否有一个简单的方法来处理逃生没有写这么多的字符。

  test.sh 
 
 director =Apparel& Accessories>服装> Activewear
＃任何逃避空间的动作&> ??? 
 hadoop fs -ls $ director 
  

解决方案

定义您的示例中的特定字符串， Apparel&配件>服装>活动服，双引号或单引号将工作;

在 shell （任何POSIX-兼容的外壳），您如何将引用到变量与您定义一样重要。

要安全地将 引用到以前定义的变量中，而没有副作用，请将其包含在双引号中，例如$ directory 。

要定义 literal（逐字）字符串：

（相反，要使用嵌入式变量引用或定义变量>嵌入式命令替换或嵌入式算术表达式，请使用双重引号（）。 p>

• 如果您的字符串包含 NO 单个引号：

  
  
  
  
  

  • 使用单引号字符串，例如：

     目录='Appare l&配件>服装> Activewear'
      

  
  

一个单引号的字符串不受shell 的任何解释，因此通常是定义文字 的最安全的选项。 >。请注意，字符串可以跨越多行;例如：

  multiline ='line 1 
 line 2'
  / pre> 
 
 
 
 
 
如果您的字符串 DOES包含单引号（例如，我在这里。），你想要一个解决方案，在所有 POSIX兼容的shell  p> 
 
 
 
 
 将字符串分割成多个（单引号）部分，单引号字符 strong>：
 
 
 
 
 
 
 
 
注意：可惜的是，单引号字符串不能包含单引号，甚至没有转义。
  directory ='我'在这里。 
  
字符串分为单引号 I ，然后是文字'（作为 unquoted 字符串转义为 \' ），然后在这里单引号 m。。由于零件之间没有空格，所以结果是一个单个字符串，包含 I 之后的文字单引号。
 
 
 
替代方法：如果您不介意使用多行语句，则可以使用这里引用的文档，如底部所述。 
 
 
 
 
 
 
如果您的字符串 DOES包含单引号（例如我在这里。），你想要一个解决方案，在 bash ， ksh 和 zsh  ：
 
 
 
 
 
 
使用 ANSI-C引号：
  directory = $'I\'m 
  
 
 
 
 
 
 
 
 
 
注意：如您所见，ANSI-C引用允许将单引号转换为 \' ，但请注意附加含义：其他  \< char> 序列需要解释，太;例如， \\\
 被解释为换行符 - 请参阅 http://www.gnu.org/software/bash/manual/bash.html#ANSI_002dC-Quoting  
 
 
 
 
 
 
 @chepner的帽子提示，他指出，将 POSIX兼容的方式直接包含在一个字符串中使用单引号即可逐字使用 是将 读取-r 与这里的文档使用引号打开分隔符（ -r 选项确保字符串中的 \ 字符被视为文字）。
 ＃*任何*形式的引用，而不仅仅是单引号，在开放EOF将工作。 
＃注意，$ HOME将不会被扩展。 
＃（如果你没有引用开头的EOF，它会。）
读-r目录<'EOF'
我在这里$ HOME 
 EOF 
  
 
 
 
 
 
请注意，这里的文档创建 stdin 在这种情况下，输入（读取）。因此，您不能使用此技术直接传递生成的字符串作为参数。
 
 
 
In C#, there is a verbatim string so that,
string c = "hello \t world";               // hello     world
string d = @"hello \t world";              // hello \t world
I am new to shell script, is there a similar method in shell?

Because I have many folders with the name like "Apparel & Accessories > Clothing > Activewear", I want to know if there is a easy way to process the escape characters without write so many .
test.sh

director="Apparel & Accessories > Clothing > Activewear"
# any action to escape spaces, &, >   ???
hadoop fs -ls $director

解决方案
For definining the specific string in your example, Apparel & Accessories > Clothing > Activewear, either double quotes or single quotes will work; referring to it later is a different story, however:

In the shell (any POSIX-compatible shell), how you refer to a variable is just as important as how you define it.

To safely refer to a previously defined variable without side-effects, enclose it in double quotes, e.g., "$directory".

To define [a variable as] a literal (verbatim) string:

(By contrast, to define a variable with embedded variable references or embedded command substitutions or embedded arithmetic expressions, use double quotes (").)


If your string contains NO single quotes: 


Use a single-quoted string, e.g.:
directory='Apparel & Accessories > Clothing > Activewear'




A single-quoted string is not subject to any interpretation by the shell, so it's generally the safest option for defining a literal. Note that the string may span multiple lines; e.g.:
        multiline='line 1
        line 2'



If your string  DOES contain single quotes (e.g., I'm here.) and you want a solution that works in all POSIX-compatible shells:


Break the string into multiple (single-quoted) parts and splice in single-quote characters:



Note: Sadly, single-quoted strings cannot contain single quotes, not even with escaping.
        directory='I'\''m here.' 
The string is broken into into single-quoted I, followed by literal ' (escaped as an unquoted string as \'), followed by single-quoted m here.. By virtue of having NO spaces between the parts, the result is a single string containing a literal single quote after I.

Alternative: if you don't mind using a multiline statement, you can use a quoted here document, as described at the bottom.


If your string  DOES contain single quotes (e.g., I'm here.) and you want a solution that works in bash, ksh, and zsh:


Use ANSI-C quoting:
directory=$'I\'m here.' 




Note: As you can see, ANSI-C quoting allows for escaping single quotes as \', but note the additional implications: other \<char> sequences are subject to interpretation, too; e.g., \n is interpreted as a newline character - see http://www.gnu.org/software/bash/manual/bash.html#ANSI_002dC-Quoting



Tip of the hat to @chepner, who points out that the POSIX-compatible way of directly including a single quote in a string to be used verbatim is to use read -r with a here document using a quoted opening delimiter (the -r option ensures that \ characters in the string are treated as literals).
# *Any* form of quoting, not just single quotes, on the opening EOF will work.
# Note that $HOME will by design NOT be expanded.
# (If you didn't quote the opening EOF, it would.)
read -r directory <<'EOF'
I'm here at $HOME
EOF



Note that here documents create stdin input (which read reads in this case). Therefore, you cannot use this technique to directly pass the resulting string as an argument.


                        
这篇关于shell中有没有方法来忽略转义字符？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！