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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;



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



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包含引号(例如,我在这里。),你想要一个解决方案,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包含引号(例如我在这里。),你想要一个解决方案, bash ksh 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






@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.

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09-02 01:25