For getting the attribute value from the below mentioned xml for attribute code from tag c
random.xml
<a>
<b>
<c id="123" code="abc" date="12-12-2022"/>
<c id="123" code="efg" date="12-12-2022"/>
<c id="123" date="12-12-2022"/>
</b>
</a>
Currently the logic is:
cat random.xml | egrep "<c.*/>" | awk -F1 ' /code=/ {f=NR} f&&NR-1==f' RS='"'
How does the above logic work to get the values of code from tag c?
Getting the expected output:
abc
efg
Firstly observe that
cat random.xml | egrep "<c.*/>" | awk -F1 ' /code=/ {f=NR} f&&NR-1==f' RS='"'
is of dubious quality, as
egrep does not require standard input, it can read file itself, so you have useless use of cat
simple pattern is used in egrep which will work equally well in common grep, no need to summon ehanced grep, this usage is overkill
1 is set as field separator in awk, but code does not make any use of fields mechanism
after fixing these issue code looks following way
grep "<c.*/>" random.xml | awk ' /code=/ {f=NR} f&&NR-1==f' RS='"'
How it does work: select lines which contain <c followed by zero-or-more any characters followed by />, then instruct awk that row are separated by qoutes (") when row does contain code= set f variable value to number of row, print such row that f is set to non-zero value and f value is equal to current number of lines minus one, which does mean print rows which are directly after row containing code=.
Observe that GNU AWK is poorly suited for working with XML and using regular expression against XML is very poor idea, as XML is not Chomsky Type 3 contraption.
If possible use proper tools for working with XML data, e.g. hxselect might be used following way, let file.xml content be
<a>
<b>
<c id="123" code="abc" date="12-12-2022"/>
<c id="123" code="efg" date="12-12-2022"/>
<c id="123" date="12-12-2022"/>
</b>
</a>
then
hxselect -c -s '\n' 'c[code]::attr(code)' < file.xml
gives output
abc
efg
Explanation: -c get just value rather than name and value, -s '\n' shear using newline, i.e. each value will be on own line c[code] is CSS3 selector meaning any c tag with attribute code, ::attr(code) is hxselect feature meaning get attribute named code. Observe that this solution is more robust than peculiar cat-egrep-awk pipeline as is immune to e.g. other whitespace usage in file (whitespaces outside tags in XML are optional).
This might be an awk question but parsing XML should be done with XML tools.
Here's an example with Xidel (available here for a few OSs) and a standard XPath expression:
xidel --xpath '//c[#code]/#code' random.xml
note: //c[#code] selects the c nodes that have a code attribute, and .../#code outputs the value of the code attribute.
Output
abc
efg
If your input always looks likes the sample XML then you can make the code attribute itself a field separator, and < the record separator, so that you can easily extract the value as the second field when the first field is the tag name c:
awk -F' .*code="|" ' -vRS='<' '$1=="c"{print $2}'
Demo: https://awk.js.org/?snippet=Lz6yx7
I have been wondering how is it possible to scrap Wikipedia information. For example, I have a list of world cities and want to obtain their approximate latitude and longitude. Take Miami as an example. When I type curl https://en.wikipedia.org/wiki/Miami | grep -E '(latitude|longitude)', somewhere in the HTML there will be a tag mark like below.
<span class="latitude">25°46′31″N</span> <span class="longitude">80°12′31″W</span>
I know I can extract it with some regex string, but I speak a very poor regexish. Can some of you help me on this?
With xidel and xpath:
$ xidel -se '
concat(
(//span[#class="latitude"]/text())[1],
" ",
(//span[#class="longitude"]/text())[1]
)
' 'https://en.wikipedia.org/wiki/Miami'
Output
25°46′31″N 80°12′31″W
Or
saxon-lint --html --xpath '<XPATH EXP>' <URL>
If you want most known tools:
curl -s 'https://en.wikipedia.org/wiki/Miami' > Miami.html
xmlstarlet format -H Miami.html 2>/dev/null | sponge Miami.html
xmlstarlet sel -t -v '<XPATH EXP>' Miami.html
Not mentioned, but regex are not the right tool to parse HTML
You can't parse HTML with RegEx. Please use an HTML-parser like xidel instead:
$ xidel -s "https://en.wikipedia.org/wiki/Miami" -e '
(//span[#class="geo-dms"])[1],
(//span[#class="geo-dec"])[1],
(//span[#class="geo"])[1],
replace((//span[#class="geo"])[1],";",())
'
25°46′31″N 80°12′31″W
25.775163°N 80.208615°W
25.775163; -80.208615
25.775163 -80.208615
Take your pick.
I want to query the names of all the persons in the test.xml below.
<body>
<person name="abc"></person>
<person name="def"></person>
<person name="ghi"></person>
</body>
basic query
This has the problem of including "name", which I don't want.
$ xmllint --xpath '//body/person/#name' test.xml`
name="abc"
name="def"
name="ghi"
string function
Using the string function, I only get one result.
$ xmllint --xpath 'string(//body/person/#name)' test.xml
abc
sed and grep
This works but looks needlessly complicated to me.
xmllint --xpath '//body/person/#name' test.xml | grep -o '"\([^"]*\)"' | sed 's|"||g'
abc
def
ghi
Question
Is it possible to get multiple values without the attribute name and without using another tool like grep?
I don't know about xmllint, but xmlstarlet can do it:
xmlstarlet sel -t -v 'body/person/#name' test.xml
Output:
abc
def
ghi
I want to read xml file and set its value into a variable.
for example ,
qhr2400.xml
<XML>
<OPERATION type="1">
<TABLENAME>TABLE</TABLENAME>
<ROWSET>
<ROW>
<CLLI>518</CLLI>
<COLLECTION_DATE>06/04/20 00:45:00</COLLECTION_DATE>
<SS7RT>99</SS7RT>
<AQPRT_1>84</AQPRT_1>
<L7RMSUOCT_01>80</L7RMSUOCT_01>
<L7RMSUOCT_02>80</L7RMSUOCT_02>
</ROW>
</ROWSET>
</OPERATION>
</XML>
I want its value in a variable like $CLLI =518, $COLLECTION_DATE = 06/04/20 00:45:00, SS7RT = 99..
so that I can use these values further to write an insert query.
Basically I want to load this .xml data into a database table.
this is what I tried.
read_xml.sh
awk 'NF==1 && (/ +<[a-zA-Z]+>/ || /^<[a-zA-Z]+>/ || / +<\/[a-zA-Z]+>/){
next
}
{
sub(/^ +/,"")
gsub(/\"|<|>/,"",$0);
sub(/\/.*/,"");
if($0){
print
}
}
' qhr2400.xml
Output
OPERATION type=1
CLLI5018
COLLECTION_DATE06
SS7RT99
AQPRT_184
L7RMSUOCT_0180
L7RMSUOCT_0280
Any help is appreciated.
Thanks!
Don't parse XML/HTML with regex, use a proper XML/HTML parser and a powerful xpath query.
theory :
According to the compiling theory, XML/HTML can't be parsed using regex based on finite state machine. Due to hierarchical construction of XML/HTML you need to use a pushdown automaton and manipulate LALR grammar using tool like YACC.
Check this thread too, why-its-not-possible-to-use-regex-to-parse-html-xml
realLife©®™ everyday tool in a shell :
You can use one of the following :
xmllint often installed by default with libxml2, xpath1
xmlstarlet can edit, select, transform... Not installed by default, xpath1
xpath installed via perl's module XML::XPath, xpath1
xidel xpath3
saxon-lint my own project, wrapper over #Michael Kay's Saxon-HE Java library, xpath3
or you can use high level languages and proper libs, I think of :
python's lxml (from lxml import etree)
perl's XML::LibXML, XML::XPath, XML::Twig::XPath, HTML::TreeBuilder::XPath
ruby nokogiri, check this example
php DOMXpath, check this example
Check: Using regular expressions with HTML tags
Fot this, you need an XML parser and xpath query in your shell, see:
$ xidel -se '//CLLI/text()' file.xml
When fixed your XML (opening/closing tag missmatch: TABLENANE/TABLENAME):
xmllint --xpath '//CLLI/text()' file
This command is installed with libxml2 and is far than exotic because it's installed by default on many Linux distros
Output
518
So now, you can retrieve all wanted values in shell variables, one example:
$ collectiondate=$(xidel -se '//COLLECTION_DATE/text()' file)
$ echo "$collectiondate"
But, please, don't use awk nor regex to parse XML.
There's others tools, check:
How to execute XPath one-liners from shell?
Check too: Using regular expressions with HTML tags (same thing for XML)
Going further
declare -A arr
for i in CLLI COLLECTION_DATE SS7RT; do
read arr[$i] < <(xmllint --xpath "//$i/text()" file.xml)
done
Now you have an associative array with CLLI COLLECTION_DATE SS7RT keys:
Keys:
printf '%s\n' "${!arr[#]}"
CLLI
SS7RT
COLLECTION_DATE
Values:
$ printf '%s\n' "${arr[#]}"
518
99
06/04/20 00:45:00
for COLLECTION_DATE:
$ echo "${arr[COLLECTION_DATE]}"
06/04/20 00:45:00
It's possible to feed a numeric array in one line too:
readarray a < <(xidel -se '//*[self::CLLI or self::COLLECTION_DATE or self::SS7RT]/text()' file.xml)
I want its value in a variable like $CLLI =518, $COLLECTION_DATE = 06/04/20 00:45:00, SS7RT = 99.. so that I can use these values further to write an insert query.
I'm going to interpret this as; you want every child-node, and its value, in the "ROW"-node exported as a variable.
As "Gilles Quenot" already mentioned, please don't parse xml with regex. I'd suggest you give xidel a try.
You could do it manually and call xidel for each and every node...
CLLI=$(xidel -s qhr2400.xml -e '//CLLI')
COLLECTION_DATE=$(xidel -s qhr2400.xml -e '//COLLECTION_DATE')
[...]
...but xidel itself can also export variables, multiple at once even:
#multiple queries, multiple declarations:
xidel -s qhr2400.xml -e 'CLLI:=//CLLI' -e 'COLLECTION_DATE:=//COLLECTION_DATE' -e '[...]' --output-format=bash
#or one query, multiple declarations:
xidel -s qhr2400.xml -e 'CLLI:=//CLLI,COLLECTION_DATE:=//COLLECTION_DATE,[...]' --output-format=bash
CLLI='518'
COLLECTION_DATE='06/04/20 00:45:00'
[...]
The output are just strings. To actually set/export these variables you have to use Bash's eval built-in command:
eval "$(xidel -s qhr2400.xml -e 'CLLI:=//CLLI,COLLECTION_DATE:=//COLLECTION_DATE,[...]' --output-format=bash)"
And finally, to do it fully automatic for every child-node in the "ROW"-node:
xidel -s qhr2400.xml -e '//ROW/*/name()'
CLLI
COLLECTION_DATE
SS7RT
AQPRT_1
L7RMSUOCT_01
L7RMSUOCT_02
xidel -s qhr2400.xml -e 'for $x in //ROW/*/name() return eval(x"//ROW/{$x}")'
518
06/04/20 00:45:00
99
84
80
80
xidel -s qhr2400.xml -e 'for $x in //ROW/*/name() return eval(x"{$x}:=//ROW{$x}")[0]' --output-format=bash
CLLI='518'
COLLECTION_DATE='06/04/20 00:45:00'
SS7RT='99'
AQPRT_1='84'
L7RMSUOCT_01='80'
L7RMSUOCT_02='80'
result=
eval "$(xidel -s qhr2400.xml -e 'for $x in //ROW/*/name() return eval(x"{$x}:=//ROW{$x}")[0]' --output-format=bash)"
Another approach is to use XSLT (XSL Transformation)
Here is a fixed and indented version of the OP's XML file:
$ cat demo.xml
<XML>
<OPERATION type="1">
<TABLENAME>TABLE</TABLENAME>
<ROWSET>
<ROW>
<CLLI>518</CLLI>
<COLLECTION_DATE>06/04/20 00:45:00</COLLECTION_DATE>
<SS7RT>99</SS7RT>
<AQPRT_1>84</AQPRT_1>
<L7RMSUOCT_01>80</L7RMSUOCT_01>
<L7RMSUOCT_02>80</L7RMSUOCT_02>
</ROW>
</ROWSET>
</OPERATION>
</XML>
This is the stylesheet I will use:
$ cat demo.xsl
<?xml version="1.0"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output method="text" encoding="utf-8" />
<xsl:strip-space elements="*"/>
<xsl:template match="ROW">
<xsl:text>CLLI="</xsl:text><xsl:value-of select="CLLI"/><xsl:text>" </xsl:text>
<xsl:text>COLLECTION_DATE="</xsl:text><xsl:value-of select="COLLECTION_DATE"/><xsl:text>" </xsl:text>
<xsl:text>SS7RT="</xsl:text><xsl:value-of select="SS7RT"/><xsl:text>" </xsl:text>
<xsl:text>AQPRT_1="</xsl:text><xsl:value-of select="AQPRT_1"/><xsl:text>" </xsl:text>
<xsl:text>L7RMSUOCT_01="</xsl:text><xsl:value-of select="L7RMSUOCT_01"/><xsl:text>" </xsl:text>
<xsl:text>L7RMSUOCT_02="</xsl:text><xsl:value-of select="L7RMSUOCT_02"/><xsl:text>" </xsl:text>
</xsl:template>
<xsl:template match="text()"/>
</xsl:stylesheet>
Here is a simple shell script which uses xsktproc to transform demo.xml into suitable text for input to eval in order to create shell variables for required element values.
$ cat demo.sh
#!/bin/bash
eval $(xsltproc demo.xsl demo.xml)
echo "CLLI: $CLLI"
echo "COLLECTION_DATE: $COLLECTION_DATE"
echo "SS7RT: $SS7RT"
echo "AQPRT_1: $AQPRT_1"
echo "L7RMSUOCT_01: $L7RMSUOCT_01"
echo "L7RMSUOCT_02: $L7RMSUOCT_02"
Run the script:
$ ./demo.sh
CLLI: 518
COLLECTION_DATE: 06/04/20 00:45:00
SS7RT: 99
AQPRT_1: 84
L7RMSUOCT_01: 80
L7RMSUOCT_02: 80
$
read_xml.sh
gawk '
BEGIN {
FS="<|>"
}
// {
{
if($3 ~ /[0-9]/) { vars[$2] = $3; next }
}
}
END {
print vars["CLLI"]
print vars["SS7RT"]
print vars["COLLECTION_DATE"]
# etc...
}
' qhr2400.xml
result:
518
99
06/04/20 00:45:00
of course, instead of printing in END, you can use these variables from the vars array for something.
Rejecting AWK as an XML or HTML pareser is unreasonable. AWK is great as a parser for any files, including damaged xml files. Using AWK requires more thought, instead you don't need to install any exotic software. You can save the xml file so that AWK reads some lines incorrectly but the same can be said about xml analysis tools.
EDIT:
We fix the XML file error - splitting the field into several lines.
file qhr2400.xml contains:
<CLLI>
518
</CLLI>
instead of
<CLLI>518</CLLI>
call:
cat qhr2400.xml |tr -d '\n' |sed 's/ *//g' |sed 's/</\n</g' |awk -f readxml.awk
readxml.awk is now:
BEGIN {
FS="<|>"
}
// {
{
if($3 ~ /[0-9]/) { vars[$2] = $3; next }
}
}
END {
print vars["CLLI"]
print vars["SS7RT"]
print vars["COLLECTION_DATE"]
# etc...
}
the result is correct
EDIT2
For some time, there has been a worrying fashion for adding complexity instead of simplifying the environment. The use of a ready-made additional tool is usually a quick solution and may tempt you with its simplicity of use. Unfortunately, it is not always possible to install a huge Perl or Python or Ruby environment, e.g. on a built-in system with 32MB Flash, it is not always possible to compile any smaller tool for your processor architecture or company policy can rightly prohibit adding anything to the standard set, there is also sense for one-time processing of the file. AWK, sed, tr are usually equipped and it is the only rescue then. Also, not always parsing an XML file means wanting to extract key-value pairs, it can be something completely different, e.g.
"ROW> <CLLI> 518 </CLLI> <COLLECTION" which makes useless ready analytical tools based on xpath. AWK is a programming language written specifically for parsing text files in a practicaly unlimited way if we add standard unix tools.
However, if you have little experience, better rely on ready-made solutions if possible.
I'm trying to parse some output of xmllint since hours, but I can't get it to work like i would need it.
Output of "xmllint --xpath "//fub/#name" menu.xml"*
name="Kessel" name="Lager" name="Puffer " name="Boiler.sen"
name="Boiler.jun" name="HK Senior" name="HK Junior" name="Fbh"
name="Solar" name="F.Wärme" name="Sys "
Now I need to seperate all the names (inclusive spaces) and get them in to seperate variables.
My approach was this:
fubNames=$(xmllint --xpath "//fub/#name" menu.xml | sed 's/name=//g')
for name in $fubNames
do
echo $name
done
but this does not workout because the for-loop seperates the string on spaces.
i need the names with spaces. (note: some names have a space at the end)
Does anyone know how to do this properly?
I suggest:
xmllint --xpath "//fub/#name" menu.xml | grep -o '"[^"]*"' | while IFS= read -r name; do echo "$name"; done
grep approach:
xmllint --xpath "//fub/#name" menu.xml | grep -Po 'name=\K\"([^"]+)\"'
The output:
"Kessel"
"Lager"
"Puffer "
"Boiler.sen"
"Boiler.jun"
"HK Senior"
"HK Junior"
"Fbh"
"Solar"
"F.Wärme"
"Sys "
-P option, allows Perl regular expressions
-o option, tells to print only matched parts