Groovy：嵌入式引号的字符串不会按预期执行 [英] Groovy: strings with embedded quotes don't execute as expected

问题描述

这很奇怪：使用groovy字符串来保存一些命令行来执行，我发现有时如果字符串中存在引号字符，那么执行会简单地失败。

WTF？ （更新，见下文）

这是我的测试程序：

  print1：; grep nameserver /etc/resolv.conf\".execute().text.eachLine {println it}; println
 print2：; grep'nameserver'/etc/resolv.conf\".execute().text.eachLine {println it}; println
 print3：; grep nameserver /etc/resolv.conf\"\"\".execute().text.eachLine {println it}; println
 print4：; grepnameserver/etc/resolv.conf\"\"\".execute().text.eachLine {println it}; println
 print5：; grep'nameserver'/etc/resolv.conf\"\"\".execute().text.eachLine {println it}; println
 print6：; awk / nameserver / /etc/resolv.conf.execute（）。text.eachLine {println it}; println
 print7：; awk/ nameserver /'/etc/resolv.conf\".execute（）。text.eachLine {println it}; println
 print8：; awk/ nameserver //etc/resolv.conf。execute（）。text.eachLine {println it}; println
 print9：; awk'/ nameserver /'/etc/resolv.conf。execute（）。text.eachLine {println it}; println
 print10：; awk/ nameserver / {print \ $ 2}/etc/resolv.conf。execute（）。text.eachLine {println it}; println
返回
  

结果如下：

  $ groovy weird.groovy 
 1：nameserver 10.3.0.101 
 nameserver 10.4.1.237 
 nameserver 10.2.1.34 
 
 2：
 3：nameserver 10.3.0.101 
 nameserver 10.4.1.237 
 nameserver 10.2.1.34 
 
 4：
 5：
 6：nameserver 10.3.0.101 
 nameserver 10.4.1.237 
 nameserver 10.2.1.34 
 
 7：
 8：nameserver 10.3.0.101 
 nameserver 10.4 .1.237 
 nameserver 10.2.1.34 
域名lnx.copansys.com 
搜索lnx.copansys.com tst.copansys.com copansys.com 
 
 9：
 10：
  

更新

下面是另外一个例子： $ b bash -c echo Hello.execute （）.text.eachLine {println it}
bash -c echo'Hello'。execute（）。text.eachLine {println it}
bash -c echo \'Hello\ '.execute（）。text.eachLine {println it}


结果：

  groovy> bash -c echo Hello.execute（）。text.eachLine {println it} 
 groovy> bash -c echo'Hello'。execute（）。text.eachLine {println it} 
 groovy> bash -c echo \'Hello\'。execute（）。text.eachLine {println it} 
 
'Hello！'
  

观察嵌入反斜杠引用的'似乎没有帮助。

解决方案

使用 String.execute（）执行命令时，它们不会被命令shell解析。引号被传递给执行的实际命令;在这种情况下，grep和awk。

通过用echo替换grep和awk来说明：

  print1：; echo something.execute（）。text.eachLine {println it}; println
 print2：; echo'something'。execute（）。text.eachLine {println it}; println
 print3：; echo something。execute（）。text.eachLine {println it}; println
 print4：; echosomething.execute（）。text.eachLine {println it}; println
 print5：; echo'something'。execute（）。text.eachLine {println it}; println
  

结果如下：

 1：something 
 
 2：'something'
 
 3：something 
 
 4：something 
 
 5：'something'
  

一个简单的解决方法是构建命令行作为字符串列表：

  [awk，'BEGIN {printhello}']。execute（） .text 
  

如果您需要更好地控制命令解析的方式，请查看 ProcessBuilder ，Java类 String.execute（）围绕着。

This is weird: using groovy strings to hold some command lines for execution, I find that sometimes if there are quote characters inside the string, the execution simply silently fails.

WTF? (Updated, see below.)

Here's my test program:

print " 1: " ; "grep nameserver /etc/resolv.conf".execute().text.eachLine {println it }          ; println ""
print " 2: " ; "grep 'nameserver' /etc/resolv.conf".execute().text.eachLine {println it }        ; println ""
print " 3: " ; """grep nameserver /etc/resolv.conf""".execute().text.eachLine {println it }      ; println ""
print " 4: " ; """grep "nameserver" /etc/resolv.conf""".execute().text.eachLine {println it }    ; println ""
print " 5: " ; """grep 'nameserver' /etc/resolv.conf""".execute().text.eachLine {println it }    ; println ""
print " 6: " ; "awk /nameserver/ /etc/resolv.conf".execute().text.eachLine{ println it }         ; println ""
print " 7: " ; "awk '/nameserver/' /etc/resolv.conf".execute().text.eachLine{ println it }       ; println ""
print " 8: " ; """awk "/nameserver/" /etc/resolv.conf""".execute().text.eachLine{ println it }   ; println ""
print " 9: " ; """awk '/nameserver/' /etc/resolv.conf""".execute().text.eachLine{ println it }   ; println ""
print "10: " ; """awk "/nameserver/{print \$2}" /etc/resolv.conf""".execute().text.eachLine{ println it }   ; println ""
return

Here's the results:

$ groovy weird.groovy 
 1: nameserver 10.3.0.101
nameserver 10.4.1.237
nameserver 10.2.1.34

 2: 
 3: nameserver 10.3.0.101
nameserver 10.4.1.237
nameserver 10.2.1.34

 4: 
 5: 
 6: nameserver 10.3.0.101
nameserver 10.4.1.237
nameserver 10.2.1.34

 7: 
 8: nameserver 10.3.0.101
nameserver 10.4.1.237
nameserver 10.2.1.34
domain lnx.copansys.com
search lnx.copansys.com tst.copansys.com copansys.com

 9: 
10: 

Update

Here's another example:

"bash -c echo Hello".execute().text.eachLine{ println it }
"bash -c echo 'Hello'".execute().text.eachLine{ println it }
"bash -c echo \'Hello\'".execute().text.eachLine{ println it }

Results:

groovy> "bash -c echo Hello".execute().text.eachLine{ println it } 
groovy> "bash -c echo 'Hello'".execute().text.eachLine{ println it } 
groovy> "bash -c echo \'Hello\'".execute().text.eachLine{ println it } 

'Hello!'

Observe that embedding a backslash-quoted ' doesn't seem to help.

解决方案

When you execute commands with String.execute(), they don't get parsed by a command shell. The quotes are passed through to the actual commands executed; in this case, grep and awk.

This is illustrated by replacing grep and awk with echo:

print " 1: " ; "echo something".execute().text.eachLine {println it }          ; println ""
print " 2: " ; "echo 'something'".execute().text.eachLine {println it }        ; println ""
print " 3: " ; """echo something""".execute().text.eachLine {println it }      ; println ""
print " 4: " ; """echo "something" """.execute().text.eachLine {println it }   ; println ""
print " 5: " ; """echo 'something'""".execute().text.eachLine {println it }    ; println ""

Which results in:

 1: something

 2: 'something'

 3: something

 4: "something"

 5: 'something'

A simple workaround is to build the command line as a list of strings:

["awk", 'BEGIN { print "hello" }'].execute().text

If you need finer control over the how the command is parsed, take a look at ProcessBuilder, the Java class String.execute() is built around.

这篇关于Groovy：嵌入式引号的字符串不会按预期执行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！