How to parse XML using shellscript

Question

I would like to know what would be the best way to parse an XML file using shellscript     Should one do it by hand   Does third tiers library exist     If you already made it if you could let me know how did you manage to do it

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Here s a solution using xml grep  because xpath wasn t part of our distributable and I didn t want to add it to all production machines      If you are looking for a specific setting in an XML file  and if all elements at a given tree level are unique  and there are no attributes  then you can use this handy function     File to be parsed xmlFile  xxxxxxx     use xml grep to find settings in an XML file   Input   1   path to setting function getXmlSetting            Filter out the element name for parsing     local element  echo  1   sed  s                  Verify the element is not empty     local check   element  getXmlSetting invalid input   1         Parse out the CDATA from the XML element       1  Find the element  xml grep        2  Remove newlines  tr -d  n        3  Extract CDATA by looking for  element gt  CDATA  lt element        4  Remove leading and trailing spaces     local getXmlSettingResult  xml grep --cond  1  xmlFile 2 gt  dev null   tr -d   n    sed -n -e  s    element gt    space          space         space        space     lt    element    1 p          Return the result     echo  getXmlSettingResult     EXAMPLE logPath  getXmlSetting   config logs path  check   logPath   XML file missing   config logs path     This will work with this structure    lt config gt     lt logs gt        lt path gt  path to logs lt  path gt     lt logs gt   lt  config gt    It will also work with this  but it won t keep the newlines     lt config gt     lt logs gt        lt path gt             path to logs       lt  path gt     lt logs gt   lt  config gt    If you have duplicate  lt config gt  or  lt logs gt  or  lt path gt   then it will only return the last one   You can probably modify the function to return an array if it finds multiple matches   FYI  This code works on RedHat 6 3 with GNU BASH 4 1 2  but I don t think I m doing anything particular to that  so should work everywhere   NOTE  For anybody new to scripting  make sure you use the right types of quotes  all three are used in this code  normal single quote   literal  backward single quote   execute  and double quote   group

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I am surprised no one has mentioned xmlsh  The mission statement        A command line shell for XML Based on the philosophy and design of the   Unix Shells      xmlsh provides a familiar scripting environment  but specifically   tailored for scripting xml processes    A list of shell like commands are provided here   I use the xed command a lot which is equivalent to sed for XML  and allows XPath based search and replaces

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A rather new project is the xml-coreutils package featuring xml-cat  xml-cp  xml-cut  xml-grep       http   xml-coreutils sourceforge net contents html

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Here s a full working example  If it s only extracting email addresses you could just do something like  1  Suppose XML file spam xml is like   lt spam gt   lt victims gt     lt victim gt       lt name gt The Pope lt  name gt       lt email gt pope vatican gob va lt  email gt       lt is satan gt 0 lt  is satan gt     lt  victim gt     lt victim gt       lt name gt George Bush lt  name gt       lt email gt father nwo com lt  email gt       lt is satan gt 1 lt  is satan gt     lt  victim gt     lt victim gt       lt name gt George Bush Jr lt  name gt       lt email gt son nwo com lt  email gt       lt is satan gt 0 lt  is satan gt     lt  victim gt   lt  victims gt   lt  spam gt    2  You can get the emails and process them with this short bash code        bin bash emails    grep -oP     lt  email gt     lt       my path spam xml     for i in    emails     do   echo   i     emails  i        instead of echo use the values to send emails  etc done   Result of this example is     0 pope vatican gob va 1 father nwo com 2 son nwo com   Important note  Don t use this for serious matters  This is OK for playing around  getting quick results  learning grep  etc  but you should definitely look for  learn and use an XML parser for production  see Micha s comment below

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There s also xmlstarlet  which is available for Windows as well    http   xmlstar sourceforge net doc xmlstarlet txt

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Do you have xml grep installed  It s a perl based utility standard on some distributions  it came pre-installed on my CentOS system    Rather than giving it a regular expression  you give it an xpath expression

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This really is beyond the capabilities of shell script  Shell script and the standard Unix tools are okay at parsing line oriented files  but things change when you talk about XML  Even simple tags can present a problem   lt MYTAG gt Data lt  MYTAG gt    lt MYTAG gt       Data  lt  MYTAG gt    lt MYTAG param  quot value quot  gt Data lt  MYTAG gt    lt MYTAG gt  lt ANOTHER TAG gt Data  lt  ANOTHER TAG gt  lt MYTAG gt   Imagine trying to write a shell script that can read the data enclosed in   The three very  very simply XML examples all show different ways this can be an issue  The first two examples are the exact same syntax in XML  The third simply has an attribute attached to it  The fourth contains the data in another tag  Simple sed  awk  and grep commands cannot catch all possibilities  You need to use a full blown scripting language like Perl  Python  or Ruby  Each of these have modules that can parse XML data and make the underlying structure easier to access  I ve use XML  Simple in Perl  It took me a few tries to understand it  but it did what I needed  and made my programming much easier

User · Answer

You could try xmllint     The xmllint program parses one or more   XML files  specified on the command   line as xmlfile  It prints various   types of output  depending upon the   options selected  It is useful for   detecting errors both in XML code and   in the XML parser itse   It allows you select elements in the XML doc by xpath  using the --pattern option   On Mac OS X  Yosemite   it is installed by default  On Ubuntu  if it is not already installed  you can run apt-get install libxml2-utils

User · Answer

Try using xpath  You can use it to parse elements out of an xml tree   http   www ibm com developerworks xml library x-tipclp index html

User · Answer

Try sgrep  It s not clear exactly what you are trying to do  but I surely would not attempt writing an XML parser in bash

[linux] How to parse XML using shellscript?

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