How to remove comment from XML using shell script

Question

I would like to get port from server.xml that is tomcat server configuration file.

my server.xml is below.

How can I get port from server.xml without comment part

I just want to get only 50000 without 8080.

<Connector port="50000"  maxHttpHeaderSize="8192" protocol="HTTP/1.1"
           maxThreads="2000" minSpareThreads="50" maxSpareThreads="150" />    
<!--
<Connector executor="tomcatThreadPool"
           port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />
-->

Hi, Does any of the following answer helped you in your goal ? If it does please accept/upvote the answer for closure. — P...., Mar 27 '17 at 06:17
Possible duplicate of [Remove XML comments using Regex in bash](http://stackoverflow.com/questions/19230407/remove-xml-comments-using-regex-in-bash) — Samuel Kirschner, Mar 29 '17 at 07:27

Samuel Kirschner · Accepted Answer · 2017-03-23T18:19:00.337

The most simple solution to remove all comments from a textfile I could come up with is:

| sed 's/<!--/\x0<!--/g;s/-->/-->\x0/g' | grep -zv '^<!--' | tr -d '\0' |

To explain:

The sed will put in a null char like this:

<Connector port="50000"  maxHttpHeaderSize="8192" protocol="HTTP/1.1"
           maxThreads="2000" minSpareThreads="50" maxSpareThreads="150" />    
\0<!--
<Connector executor="tomcatThreadPool"
           port="8080" protocol="HTTP/1.1"
           connectionTimeout="20000"
           redirectPort="8443" />
-->\0

than the grep -z will treat that character as "line seperator" and remove the middle part, and finally tr -d will remove the \0 again so that any following grep's won't treat it as a binary file.

just combine it with the grep you are already using e.g.:

 cat server.xml | sed 's/<!--/\x0<!--/g;s/-->/-->\x0/g' | grep -zv '^<!--' | tr -d '\0' | grep -o 'port="[0-9]*' | grep -o '[0-9]*$'

output:

score 1 · Answer 2 · answered Nov 07 '21 at 19:56

The title is rather misleading, because what you really want is to extract the value of the "port"-attribute.
Please don't use RegEx to parse XML, but use an XML-parser like xidel or xmlstartlet instead.

$ xidel -s server.xml -e '//@port'

$ xmlstarlet sel -t -v '//@port' server.xml

P.... · Answer 3 · 2017-03-23T07:05:32.200

0

Following are different results , Please check look arounds for more details.

grep -oP 'port=.*? (?=maxHttpHeaderSize)' server.xml
port="50000"

grep -oP 'port=\K.*? (?=maxHttpHeaderSize)' server.xml
"50000"

grep -oP 'port="\K.*?(?="  maxHttpHeaderSize=)'
50000

edited Mar 23 '17 at 07:05

answered Mar 23 '17 at 06:43

P....

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In my case My server.xml is below state. so I need to get only 50000 value. ` ` – user1855851 Mar 23 '17 at 08:43
add this in question as in comments its difficult to understand. – P.... Mar 23 '17 at 09:07

score 0 · Answer 4 · answered Oct 31 '21 at 16:54

this is a bash script with sed. I think that it is the best solution with sed. if your system is OSX. (IE. macbook pro) you should install a gnu sed firstly.

sed -E  -e\
':start
/<!--/ {
   :loop
   /-->/ {
            s/-->/mockend102499883356/
            s/<!--.*mockend102499883356//
            /<!--/ {
                   b loop
            }
            b done
   }
   :add
   N
   b loop
   :done
}'  filename.xml;

this blog is the detail about the code. if you can read in chinese. remove xml comment in pom.xml of maven project

How to remove comment from XML using shell script

4 Answers4