如何使用sed / grep提取两个单词之间的文本？

我试图输出一个字符串，其中包含一个字符串的两个单词之间的所有内容：

输入：

"Here is a String"

输出：

"is a"

使用：

sed -n '/Here/,/String/p'

包括端点，但我不想包含它们。

sed -e 's/Here\(.*\)String/\1/'

GNU grep还可以支持正面和负面的提前和回溯：对于您的情况，命令为：

echo "Here is a string" | grep -o -P '(?<=Here).*(?=string)'

如果有多次出现Here并且string，你可以选择你是否想从第一场比赛Here和最后的string或单独匹配。在正则表达式的方面，它被称为贪婪匹配（第一情况）或非贪婪匹配（第二种情况）

$ echo 'Here is a string, and Here is another string.' | grep -oP '(?<=Here).*(?=string)' # Greedy match
 is a string, and Here is another 
$ echo 'Here is a string, and Here is another string.' | grep -oP '(?<=Here).*?(?=string)' # Non-greedy match (Notice the '?' after '*' in .*)
 is a 
 is another 

接受的答案不会删除之前Here或之后的文本String。这将：

sed -e 's/.*Here\(.*\)String.*/\1/'

主要区别是.*紧接在之前Here和之后String。

您可以单独在Bash中剥离字符串：

$ foo="Here is a String"
$ foo=${foo##*Here }
$ echo "$foo"
is a String
$ foo=${foo%% String*}
$ echo "$foo"
is a
$

如果您有一个包含PCRE的GNU grep，则可以使用零宽度的断言：

$ echo "Here is a String" | grep -Po '(?<=(Here )).*(?= String)'
is a

通过GNU awk，

$ echo "Here is a string" | awk -v FS="(Here|string)" '{print $2}'
 is a 

具有-P（perl-regexp）参数的grep 支持\K，它有助于丢弃先前匹配的字符。在我们的例子中，先前匹配的字符串被Here删除，因此从最终输出中将其丢弃。

$ echo "Here is a string" | grep -oP 'Here\K.*(?=string)'
 is a 
$ echo "Here is a string" | grep -oP 'Here\K(?:(?!string).)*'
 is a 

如果您想要输出，is a那么可以尝试以下方法，

$ echo "Here is a string" | grep -oP 'Here\s*\K.*(?=\s+string)'
is a
$ echo "Here is a string" | grep -oP 'Here\s*\K(?:(?!\s+string).)*'
is a

如果您的文件较长且包含多行，则首先打印数字行会很有用：

cat -n file | sed -n '/Here/,/String/p'

这可能对您有用（GNU sed）：

sed '/Here/!d;s//&\n/;s/.*\n//;:a;/String/bb;$!{n;ba};:b;s//\n&/;P;D' file 

这会在换行符上的两个标记之间（在本例中为Here和String）显示文本的每种表示形式，并在文本中保留换行符。

上述所有解决方案都有缺陷，其中最后一个搜索字符串在字符串的其他位置重复。我发现最好编写一个bash函数。

    function str_str {
      local str
      str="${1#*${2}}"
      str="${str%%$3*}"
      echo -n "$str"
    }

    # test it ...
    mystr="this is a string"
    str_str "$mystr" "this " " string"

您可以使用两个s命令

$ echo "Here is a String" | sed 's/.*Here//; s/String.*//'
 is a 

也可以

$ echo "Here is a StringHere is a String" | sed 's/.*Here//; s/String.*//'
 is a

$ echo "Here is a StringHere is a StringHere is a StringHere is a String" | sed 's/.*Here//; s/String.*//'
 is a 

要了解 sed命令，我们必须逐步构建它。

这是你的原文

user@linux:~$ echo "Here is a String"
Here is a String
user@linux:~$ 

让我们尝试Here使用substition选项删除字符串sed

user@linux:~$ echo "Here is a String" | sed 's/Here //'
is a String
user@linux:~$ 

在这一点上，我相信你将能够去除String以及

user@linux:~$ echo "Here is a String" | sed 's/String//'
Here is a
user@linux:~$ 

但这不是您想要的输出。

要组合两个sed命令，请使用-eoption

user@linux:~$ echo "Here is a String" | sed -e 's/Here //' -e 's/String//'
is a
user@linux:~$ 

希望这可以帮助

您可以使用\1（请参阅http://www.grymoire.com/Unix/Sed.html#uh-4）：

echo "Hello is a String" | sed 's/Hello\(.*\)String/\1/g'

括号内的内容将存储为\1。

问题。 我存储的Claws Mail消息包装如下，并且我试图提取“主题”行：

Subject: [SLC38A9 lysosomal arginine sensor; mTORC1 pathway] Key molecular
 link in major cell growth pathway: Findings point to new potential
 therapeutic target in pancreatic cancer [mTORC1 Activator SLC38A9 Is
 Required to Efflux Essential Amino Acids from Lysosomes and Use Protein as
 a Nutrient] [Re: Nutrient sensor in key growth-regulating metabolic pathway
 identified [Lysosomal amino acid transporter SLC38A9 signals arginine
 sufficiency to mTORC1]]
Message-ID: <20171019190902.18741771@VictoriasJourney.com>

在此线程中的A2中，如何使用sed / grep提取两个单词之间的文本？只要匹配的文本不包含换行符，下面的第一个表达式就可以“起作用”：

grep -o -P '(?<=Subject: ).*(?=molecular)' corpus/01

[SLC38A9 lysosomal arginine sensor; mTORC1 pathway] Key

但是，尽管尝试了多种变体（.+?; /s; ...），但我无法使它们起作用：

grep -o -P '(?<=Subject: ).*(?=link)' corpus/01
grep -o -P '(?<=Subject: ).*(?=therapeutic)' corpus/01
etc.

解决方案1。

Per 在不同行的两个字符串之间提取文本

sed -n '/Subject: /{:a;N;/Message-ID:/!ba; s/\n/ /g; s/\s\s*/ /g; s/.*Subject: \|Message-ID:.*//g;p}' corpus/01

这使

[SLC38A9 lysosomal arginine sensor; mTORC1 pathway] Key molecular link in major cell growth pathway: Findings point to new potential therapeutic target in pancreatic cancer [mTORC1 Activator SLC38A9 Is Required to Efflux Essential Amino Acids from Lysosomes and Use Protein as a Nutrient] [Re: Nutrient sensor in key growth-regulating metabolic pathway identified [Lysosomal amino acid transporter SLC38A9 signals arginine sufficiency to mTORC1]]                              

解决方案2. *

每我如何使用sed替换换行符（\ n）？

sed ':a;N;$!ba;s/\n/ /g' corpus/01

将用空格替换换行符。

如何使用sed / grep在两个单词之间提取文本，将其与A2链接起来？，我们得到：

sed ':a;N;$!ba;s/\n/ /g' corpus/01 | grep -o -P '(?<=Subject: ).*(?=Message-ID:)'

这使

[SLC38A9 lysosomal arginine sensor; mTORC1 pathway] Key molecular  link in major cell growth pathway: Findings point to new potential  therapeutic target in pancreatic cancer [mTORC1 Activator SLC38A9 Is  Required to Efflux Essential Amino Acids from Lysosomes and Use Protein as  a Nutrient] [Re: Nutrient sensor in key growth-regulating metabolic pathway  identified [Lysosomal amino acid transporter SLC38A9 signals arginine  sufficiency to mTORC1]] 

此变体删除双倍空格：

sed ':a;N;$!ba;s/\n/ /g; s/\s\s*/ /g' corpus/01 | grep -o -P '(?<=Subject: ).*(?=Message-ID:)'

给予

[SLC38A9 lysosomal arginine sensor; mTORC1 pathway] Key molecular link in major cell growth pathway: Findings point to new potential therapeutic target in pancreatic cancer [mTORC1 Activator SLC38A9 Is Required to Efflux Essential Amino Acids from Lysosomes and Use Protein as a Nutrient] [Re: Nutrient sensor in key growth-regulating metabolic pathway identified [Lysosomal amino acid transporter SLC38A9 signals arginine sufficiency to mTORC1]]