无法将sed或awk命令的输出分配给变量？只能打印它们 [英] Unable to assign output of sed or awk command to variables? Can only print them

问题描述

使用此命令从文本文件中提取2行：

  cat file1 | grep -A7 SECTIONA | grep -E'Address | BackupAddress'
  

这会产生下面两行：

 地址host1 port_1地址
 BackupAddress host2 port_2 BackupAddress 
  

我需要将主机和端口列分配给不同的全局变量，以便稍后在脚本中使用。

  hosta =host1
 porta =port_1
 hostb =host2
 portb =port_2
  

一个成员建议我使用这个，我得到所需的输出，但是我不能在当前shell中使用变量？当我尝试打印或使用它们时，它们显得空白。我也有一个awk解决方案来获得所需的输出，但是sed和awk命令都只是打印上面的内容，并且不会创建变量？

  sed -n's / ^ Address * \（[^] \ + \）* \（[^] \ + \）。* / hosta =\ 1\ nporta = \2/ p; 
s / ^ BackupAddress * \（[^] \ + \）* \（[^] \ + \）。* / hostb =\ 1\\\
portb =\ 2/ p'file1 
  

我可以通过将sed和awk命令分为4部分并运行相同的查询4次，但必须有更好的方法。例如我可以这样做：

  hosta =`cat file | sed /或/ awk命令`
 porta =`cat file | sed /或/ awk命令`
 hostb =`cat file | sed /或/ awk命令`
 portb =`cat file | sed /或/ awk命令`
  

当我使用awk或sed命令执行查询以获得所需输出他们被分配到变量，我可以打印或使用我喜欢的变量;但我不想运行该查询4次。

任何人都可以帮忙请

解决方案

检查该输入不包含无效字符，则输出可以与evaled相同。在这种情况下，负字符集 [^] 应该被正字符集替换以匹配预期字符。

<$ p $ output = $（sed ...）
eval$ output


或

  eval$（sed ...）
  

或

 来源<（sed。 ..）
  

I use this command to extract 2 lines from a text file:

cat file1 | grep -A7 SECTIONA  | grep -E 'Address|BackupAddress'

This produces the two lines below:

Address host1  port_1  Address
BackupAddress host2 port_2  BackupAddress

I need to assign (not print) the host and port columns to distinct global variables to use later in the script.

hosta="host1"
porta="port_1"
hostb="host2"
portb="port_2"

A member suggested I use this and I get the desired output, however I cannot use the variables in the current shell? When I try to print or use them they come out blank. I also have an awk solution to get the desired output, but both sed and awk commands just print the above and do not create the variables?

sed -n 's/^Address *\([^ ]\+\) *\([^ ]\+\).*/hosta="\1"\nporta="\2"/p;
s/^BackupAddress *\([^ ]\+\) *\([^ ]\+\).*/hostb="\1"\nportb="\2"/p' file1

I can get around all this by breaking the sed and awk command into 4 sections and run the same query 4 times but there must be a better way. for example I can do:

hosta=`cat file | sed/or/awk command` 
porta=`cat file | sed/or/awk command` 
hostb=`cat file | sed/or/awk command` 
portb=`cat file | sed/or/awk command` 

When I do the query using awk or sed command to get the desired output they get assigned to variables and I can print or use the variables as I like; but I do not want to run the query 4 times.

Can anyone help please

解决方案

Checking that input doesn't contain invalid character, the output can be sourced same as "eval"ed. in that case negative character set [^ ] should be replaced by a positive character set to match expected characters

output=$(sed ...)
eval "$output"

or

eval "$(sed ...)"

or

source <(sed ...)

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