starting from the chad's answer, here is the COMPLETE working solution to parse UML, with propper handling of comments, with just 2 little functions (more than 2 bu you can mix them all). I don't say chad's one didn't work at all, but it had too much issues with badly formated XML files: So you have to be a bit more tricky to handle comments and misplaced spaces/CR/TAB/etc.
The purpose of this answer is to give ready-2-use, out of the box bash functions to anyone needing parsing UML without complex tools using perl, python or anything else. As for me, I cannot install cpan, nor perl modules for the old production OS i'm working on, and python isn't available.
First, a definition of the UML words used in this post:
<!-- comment... -->
<tag attribute="value">content...</tag>
EDIT: updated functions, with handle of:
xml_read_dom() {
# https://stackoverflow.com/questions/893585/how-to-parse-xml-in-bash
local ENTITY IFS=\>
if $ITSACOMMENT; then
read -d \< COMMENTS
COMMENTS="$(rtrim "${COMMENTS}")"
return 0
else
read -d \< ENTITY CONTENT
CR=$?
[ "x${ENTITY:0:1}x" == "x/x" ] && return 0
TAG_NAME=${ENTITY%%[[:space:]]*}
[ "x${TAG_NAME}x" == "x?xmlx" ] && TAG_NAME=xml
TAG_NAME=${TAG_NAME%%:*}
ATTRIBUTES=${ENTITY#*[[:space:]]}
ATTRIBUTES="${ATTRIBUTES//xmi:/}"
ATTRIBUTES="${ATTRIBUTES//xmlns:/}"
fi
# when comments sticks to !-- :
[ "x${TAG_NAME:0:3}x" == "x!--x" ] && COMMENTS="${TAG_NAME:3} ${ATTRIBUTES}" && ITSACOMMENT=true && return 0
# http://tldp.org/LDP/abs/html/string-manipulation.html
# INFO: oh wait it doesn't work on IBM AIX bash 3.2.16(1):
# [ "x${ATTRIBUTES:(-1):1}x" == "x/x" -o "x${ATTRIBUTES:(-1):1}x" == "x?x" ] && ATTRIBUTES="${ATTRIBUTES:0:(-1)}"
[ "x${ATTRIBUTES:${#ATTRIBUTES} -1:1}x" == "x/x" -o "x${ATTRIBUTES:${#ATTRIBUTES} -1:1}x" == "x?x" ] && ATTRIBUTES="${ATTRIBUTES:0:${#ATTRIBUTES} -1}"
return $CR
}
and the second one :
xml_read() {
# https://stackoverflow.com/questions/893585/how-to-parse-xml-in-bash
ITSACOMMENT=false
local MULTIPLE_ATTR LIGHT FORCE_PRINT XAPPLY XCOMMAND XATTRIBUTE GETCONTENT fileXml tag attributes attribute tag2print TAGPRINTED attribute2print XAPPLIED_COLOR PROSTPROCESS USAGE
local TMP LOG LOGG
LIGHT=false
FORCE_PRINT=false
XAPPLY=false
MULTIPLE_ATTR=false
XAPPLIED_COLOR=g
TAGPRINTED=false
GETCONTENT=false
PROSTPROCESS=cat
Debug=${Debug:-false}
TMP=/tmp/xml_read.$RANDOM
USAGE="${C}${FUNCNAME}${c} [-cdlp] [-x command <-a attribute>] <file.xml> [tag | \"any\"] [attributes .. | \"content\"]
${nn[2]} -c = NOCOLOR${END}
${nn[2]} -d = Debug${END}
${nn[2]} -l = LIGHT (no \"attribute=\" printed)${END}
${nn[2]} -p = FORCE PRINT (when no attributes given)${END}
${nn[2]} -x = apply a command on an attribute and print the result instead of the former value, in green color${END}
${nn[1]} (no attribute given will load their values into your shell; use '-p' to print them as well)${END}"
! (($#)) && echo2 "$USAGE" && return 99
(( $# < 2 )) && ERROR nbaram 2 0 && return 99
# getopts:
while getopts :cdlpx:a: _OPT 2>/dev/null
do
{
case ${_OPT} in
c) PROSTPROCESS="${DECOLORIZE}" ;;
d) local Debug=true ;;
l) LIGHT=true; XAPPLIED_COLOR=END ;;
p) FORCE_PRINT=true ;;
x) XAPPLY=true; XCOMMAND="${OPTARG}" ;;
a) XATTRIBUTE="${OPTARG}" ;;
*) _NOARGS="${_NOARGS}${_NOARGS+, }-${OPTARG}" ;;
esac
}
done
shift $((OPTIND - 1))
unset _OPT OPTARG OPTIND
[ "X${_NOARGS}" != "X" ] && ERROR param "${_NOARGS}" 0
fileXml=$1
tag=$2
(( $# > 2 )) && shift 2 && attributes=$*
(( $# > 1 )) && MULTIPLE_ATTR=true
[ -d "${fileXml}" -o ! -s "${fileXml}" ] && ERROR empty "${fileXml}" 0 && return 1
$XAPPLY && $MULTIPLE_ATTR && [ -z "${XATTRIBUTE}" ] && ERROR param "-x command " 0 && return 2
# nb attributes == 1 because $MULTIPLE_ATTR is false
[ "${attributes}" == "content" ] && GETCONTENT=true
while xml_read_dom; do
# (( CR != 0 )) && break
(( PIPESTATUS[1] != 0 )) && break
if $ITSACOMMENT; then
# oh wait it doesn't work on IBM AIX bash 3.2.16(1):
# if [ "x${COMMENTS:(-2):2}x" == "x--x" ]; then COMMENTS="${COMMENTS:0:(-2)}" && ITSACOMMENT=false
# elif [ "x${COMMENTS:(-3):3}x" == "x-->x" ]; then COMMENTS="${COMMENTS:0:(-3)}" && ITSACOMMENT=false
if [ "x${COMMENTS:${#COMMENTS} - 2:2}x" == "x--x" ]; then COMMENTS="${COMMENTS:0:${#COMMENTS} - 2}" && ITSACOMMENT=false
elif [ "x${COMMENTS:${#COMMENTS} - 3:3}x" == "x-->x" ]; then COMMENTS="${COMMENTS:0:${#COMMENTS} - 3}" && ITSACOMMENT=false
fi
$Debug && echo2 "${N}${COMMENTS}${END}"
elif test "${TAG_NAME}"; then
if [ "x${TAG_NAME}x" == "x${tag}x" -o "x${tag}x" == "xanyx" ]; then
if $GETCONTENT; then
CONTENT="$(trim "${CONTENT}")"
test ${CONTENT} && echo "${CONTENT}"
else
# eval local $ATTRIBUTES => eval test "\"\$${attribute}\"" will be true for matching attributes
eval local $ATTRIBUTES
$Debug && (echo2 "${m}${TAG_NAME}: ${M}$ATTRIBUTES${END}"; test ${CONTENT} && echo2 "${m}CONTENT=${M}$CONTENT${END}")
if test "${attributes}"; then
if $MULTIPLE_ATTR; then
# we don't print "tag: attr=x ..." for a tag passed as argument: it's usefull only for "any" tags so then we print the matching tags found
! $LIGHT && [ "x${tag}x" == "xanyx" ] && tag2print="${g6}${TAG_NAME}: "
for attribute in ${attributes}; do
! $LIGHT && attribute2print="${g10}${attribute}${g6}=${g14}"
if eval test "\"\$${attribute}\""; then
test "${tag2print}" && ${print} "${tag2print}"
TAGPRINTED=true; unset tag2print
if [ "$XAPPLY" == "true" -a "${attribute}" == "${XATTRIBUTE}" ]; then
eval ${print} "%s%s\ " "\${attribute2print}" "\${${XAPPLIED_COLOR}}\"\$(\$XCOMMAND \$${attribute})\"\${END}" && eval unset ${attribute}
else
eval ${print} "%s%s\ " "\${attribute2print}" "\"\$${attribute}\"" && eval unset ${attribute}
fi
fi
done
# this trick prints a CR only if attributes have been printed durint the loop:
$TAGPRINTED && ${print} "\n" && TAGPRINTED=false
else
if eval test "\"\$${attributes}\""; then
if $XAPPLY; then
eval echo "\${g}\$(\$XCOMMAND \$${attributes})" && eval unset ${attributes}
else
eval echo "\$${attributes}" && eval unset ${attributes}
fi
fi
fi
else
echo eval $ATTRIBUTES >>$TMP
fi
fi
fi
fi
unset CR TAG_NAME ATTRIBUTES CONTENT COMMENTS
done < "${fileXml}" | ${PROSTPROCESS}
# http://mywiki.wooledge.org/BashFAQ/024
# INFO: I set variables in a "while loop" that's in a pipeline. Why do they disappear? workaround:
if [ -s "$TMP" ]; then
$FORCE_PRINT && ! $LIGHT && cat $TMP
# $FORCE_PRINT && $LIGHT && perl -pe 's/[[:space:]].*?=/ /g' $TMP
$FORCE_PRINT && $LIGHT && sed -r 's/[^\"]*([\"][^\"]*[\"][,]?)[^\"]*/\1 /g' $TMP
. $TMP
rm -f $TMP
fi
unset ITSACOMMENT
}
and lastly, the rtrim, trim and echo2 (to stderr) functions:
rtrim() {
local var=$@
var="${var%"${var##*[![:space:]]}"}" # remove trailing whitespace characters
echo -n "$var"
}
trim() {
local var=$@
var="${var#"${var%%[![:space:]]*}"}" # remove leading whitespace characters
var="${var%"${var##*[![:space:]]}"}" # remove trailing whitespace characters
echo -n "$var"
}
echo2() { echo -e "$@" 1>&2; }
oh and you will need some neat colorizing dynamic variables to be defined at first, and exported, too:
set -a
TERM=xterm-256color
case ${UNAME} in
AIX|SunOS)
M=$(${print} '\033[1;35m')
m=$(${print} '\033[0;35m')
END=$(${print} '\033[0m')
;;
*)
m=$(tput setaf 5)
M=$(tput setaf 13)
# END=$(tput sgr0) # issue on Linux: it can produces ^[(B instead of ^[[0m, more likely when using screenrc
END=$(${print} '\033[0m')
;;
esac
# 24 shades of grey:
for i in $(seq 0 23); do eval g$i="$(${print} \"\\033\[38\;5\;$((232 + i))m\")" ; done
# another way of having an array of 5 shades of grey:
declare -a colorNums=(238 240 243 248 254)
for num in 0 1 2 3 4; do nn[$num]=$(${print} "\033[38;5;${colorNums[$num]}m"); NN[$num]=$(${print} "\033[48;5;${colorNums[$num]}m"); done
# piped decolorization:
DECOLORIZE='eval sed "s,${END}\[[0-9;]*[m|K],,g"'
Either you know how to create functions and load them via FPATH (ksh) or an emulation of FPATH (bash)
If not, just copy/paste everything on the command line.
xml_read [-cdlp] [-x command <-a attribute>] <file.xml> [tag | "any"] [attributes .. | "content"]
-c = NOCOLOR
-d = Debug
-l = LIGHT (no \"attribute=\" printed)
-p = FORCE PRINT (when no attributes given)
-x = apply a command on an attribute and print the result instead of the former value, in green color
(no attribute given will load their values into your shell as $ATTRIBUTE=value; use '-p' to print them as well)
xml_read server.xml title content # print content between <title></title>
xml_read server.xml Connector port # print all port values from Connector tags
xml_read server.xml any port # print all port values from any tags
With Debug mode (-d) comments and parsed attributes are printed to stderr
Yuzem's method can be improved by inversing the order of the < and > signs in the rdom function and the variable assignments, so that:
rdom () { local IFS=\> ; read -d \< E C ;}
becomes:
rdom () { local IFS=\< ; read -d \> C E ;}
If the parsing is not done like this, the last tag in the XML file is never reached. This can be problematic if you intend to output another XML file at the end of the while loop.
You can use xpath utility. It's installed with the Perl XML-XPath package.
Usage:
/usr/bin/xpath [filename] query
or XMLStarlet. To install it on opensuse use:
sudo zypper install xmlstarlet
or try cnf xml on other platforms.
Well, you can use xpath utility. I guess perl's XML::Xpath contains it.
Command-line tools that can be called from shell scripts include:
4xpath - command-line wrapper around Python's 4Suite package
xpath - command-line wrapper around Perl's XPath library
sudo apt-get install libxml-xpath-perl
Xidel - Works with URLs as well as files. Also works with JSON
I also use xmllint and xsltproc with little XSL transform scripts to do XML processing from the command line or in shell scripts.
I am not aware of any pure shell XML parsing tool. So you will most likely need a tool written in an other language.
My XML::Twig Perl module comes with such a tool: xml_grep, where you would probably write what you want as xml_grep -t '/html/head/title' xhtmlfile.xhtml > titleOfXHTMLPage.txt (the -t option gives you the result as text instead of xml)
Check out XML2 from http://www.ofb.net/~egnor/xml2/ which converts XML to a line-oriented format.
This is really just an explaination of Yuzem's answer, but I didn't feel like this much editing should be done to someone else, and comments don't allow formatting, so...
rdom () { local IFS=\> ; read -d \< E C ;}
Let's call that "read_dom" instead of "rdom", space it out a bit and use longer variables:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
}
Okay so it defines a function called read_dom. The first line makes IFS (the input field separator) local to this function and changes it to >. That means that when you read data instead of automatically being split on space, tab or newlines it gets split on '>'. The next line says to read input from stdin, and instead of stopping at a newline, stop when you see a '<' character (the -d for deliminator flag). What is read is then split using the IFS and assigned to the variable ENTITY and CONTENT. So take the following:
<tag>value</tag>
The first call to read_dom get an empty string (since the '<' is the first character). That gets split by IFS into just '', since there isn't a '>' character. Read then assigns an empty string to both variables. The second call gets the string 'tag>value'. That gets split then by the IFS into the two fields 'tag' and 'value'. Read then assigns the variables like: ENTITY=tag and CONTENT=value. The third call gets the string '/tag>'. That gets split by the IFS into the two fields '/tag' and ''. Read then assigns the variables like: ENTITY=/tag and CONTENT=. The fourth call will return a non-zero status because we've reached the end of file.
Now his while loop cleaned up a bit to match the above:
while read_dom; do
if [[ $ENTITY = "title" ]]; then
echo $CONTENT
exit
fi
done < xhtmlfile.xhtml > titleOfXHTMLPage.txt
The first line just says, "while the read_dom functionreturns a zero status, do the following." The second line checks if the entity we've just seen is "title". The next line echos the content of the tag. The four line exits. If it wasn't the title entity then the loop repeats on the sixth line. We redirect "xhtmlfile.xhtml" into standard input (for the read_dom function) and redirect standard output to "titleOfXHTMLPage.txt" (the echo from earlier in the loop).
Now given the following (similar to what you get from listing a bucket on S3) for input.xml:
<ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<Name>sth-items</Name>
<IsTruncated>false</IsTruncated>
<Contents>
<Key>[email protected]</Key>
<LastModified>2011-07-25T22:23:04.000Z</LastModified>
<ETag>"0032a28286680abee71aed5d059c6a09"</ETag>
<Size>1785</Size>
<StorageClass>STANDARD</StorageClass>
</Contents>
</ListBucketResult>
and the following loop:
while read_dom; do
echo "$ENTITY => $CONTENT"
done < input.xml
You should get:
=>
ListBucketResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/" =>
Name => sth-items
/Name =>
IsTruncated => false
/IsTruncated =>
Contents =>
Key => [email protected]
/Key =>
LastModified => 2011-07-25T22:23:04.000Z
/LastModified =>
ETag => "0032a28286680abee71aed5d059c6a09"
/ETag =>
Size => 1785
/Size =>
StorageClass => STANDARD
/StorageClass =>
/Contents =>
So if we wrote a while loop like Yuzem's:
while read_dom; do
if [[ $ENTITY = "Key" ]] ; then
echo $CONTENT
fi
done < input.xml
We'd get a listing of all the files in the S3 bucket.
EDIT
If for some reason local IFS=\> doesn't work for you and you set it globally, you should reset it at the end of the function like:
read_dom () {
ORIGINAL_IFS=$IFS
IFS=\>
read -d \< ENTITY CONTENT
IFS=$ORIGINAL_IFS
}
Otherwise, any line splitting you do later in the script will be messed up.
EDIT 2
To split out attribute name/value pairs you can augment the read_dom() like so:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
local ret=$?
TAG_NAME=${ENTITY%% *}
ATTRIBUTES=${ENTITY#* }
return $ret
}
Then write your function to parse and get the data you want like this:
parse_dom () {
if [[ $TAG_NAME = "foo" ]] ; then
eval local $ATTRIBUTES
echo "foo size is: $size"
elif [[ $TAG_NAME = "bar" ]] ; then
eval local $ATTRIBUTES
echo "bar type is: $type"
fi
}
Then while you read_dom call parse_dom:
while read_dom; do
parse_dom
done
Then given the following example markup:
<example>
<bar size="bar_size" type="metal">bars content</bar>
<foo size="1789" type="unknown">foos content</foo>
</example>
You should get this output:
$ cat example.xml | ./bash_xml.sh
bar type is: metal
foo size is: 1789
EDIT 3 another user said they were having problems with it in FreeBSD and suggested saving the exit status from read and returning it at the end of read_dom like:
read_dom () {
local IFS=\>
read -d \< ENTITY CONTENT
local RET=$?
TAG_NAME=${ENTITY%% *}
ATTRIBUTES=${ENTITY#* }
return $RET
}
I don't see any reason why that shouldn't work
This is sufficient...
xpath xhtmlfile.xhtml '/html/head/title/text()' > titleOfXHTMLPage.txt
You can do that very easily using only bash. You only have to add this function:
rdom () { local IFS=\> ; read -d \< E C ;}
Now you can use rdom like read but for html documents. When called rdom will assign the element to variable E and the content to var C.
For example, to do what you wanted to do:
while rdom; do
if [[ $E = title ]]; then
echo $C
exit
fi
done < xhtmlfile.xhtml > titleOfXHTMLPage.txt
After some research for translation between Linux and Windows formats of the file paths in XML files I found interesting tutorials and solutions on:
Another command line tool is my new Xidel. It also supports XPath 2 and XQuery, contrary to the already mentioned xpath/xmlstarlet.
The title can be read like:
xidel xhtmlfile.xhtml -e /html/head/title > titleOfXHTMLPage.txt
And it also has a cool feature to export multiple variables to bash. For example
eval $(xidel xhtmlfile.xhtml -e 'title := //title, imgcount := count(//img)' --output-format bash )
sets $title to the title and $imgcount to the number of images in the file, which should be as flexible as parsing it directly in bash.
While there are quite a few ready-made console utilities that might do what you want, it will probably take less time to write a couple of lines of code in a general-purpose programming language such as Python which you can easily extend and adapt to your needs.
Here is a python script which uses lxml for parsing — it takes the name of a file or a URL as the first parameter, an XPath expression as the second parameter, and prints the strings/nodes matching the given expression.
#!/usr/bin/env python
import sys
from lxml import etree
tree = etree.parse(sys.argv[1])
xpath_expression = sys.argv[2]
# a hack allowing to access the
# default namespace (if defined) via the 'p:' prefix
# E.g. given a default namespaces such as 'xmlns="http://maven.apache.org/POM/4.0.0"'
# an XPath of '//p:module' will return all the 'module' nodes
ns = tree.getroot().nsmap
if ns.keys() and None in ns:
ns['p'] = ns.pop(None)
# end of hack
for e in tree.xpath(xpath_expression, namespaces=ns):
if isinstance(e, str):
print(e)
else:
print(e.text and e.text.strip() or etree.tostring(e, pretty_print=True))
lxml can be installed with pip install lxml. On ubuntu you can use sudo apt install python-lxml.
python xpath.py myfile.xml "//mynode"
lxml also accepts a URL as input:
python xpath.py http://www.feedforall.com/sample.xml "//link"
Note: If your XML has a default namespace with no prefix (e.g.
xmlns=http://abc...) then you have to use thepprefix (provided by the 'hack') in your expressions, e.g.//p:moduleto get the modules from apom.xmlfile. In case thepprefix is already mapped in your XML, then you'll need to modify the script to use another prefix.
A one-off script which serves the narrow purpose of extracting module names from an apache maven file. Note how the node name (module) is prefixed with the default namespace {http://maven.apache.org/POM/4.0.0}:
pom.xml:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modules>
<module>cherries</module>
<module>bananas</module>
<module>pears</module>
</modules>
</project>
module_extractor.py:
from lxml import etree
for _, e in etree.iterparse(open("pom.xml"), tag="{http://maven.apache.org/POM/4.0.0}module"):
print(e.text)
While it seems like "never parse XML, JSON... from bash without a proper tool" is sound advice, I disagree. If this is side job, it is waistfull to look for the proper tool, then learn it... Awk can do it in minutes. My programs have to work on all above mentioned and more kinds of data. Hell, I do not want to test 30 tools to parse 5-7-10 different formats I need if I can awk the problem in minutes. I do not care about XML, JSON or whatever! I need a single solution for all of them.
As an example: my SmartHome program runs our homes. While doing it, it reads plethora of data in too many different formats I can not control. I never use dedicated, proper tools since I do not want to spend more than minutes on reading the data I need. With FS and RS adjustments, this awk solution works perfectly for any textual format. But, it may not be the proper answer when your primary task is to work primarily with loads of data in that format!
The problem of parsing XML from bash I faced yesterday. Here is how I do it for any hierarchical data format. As a bonus - I assign data directly to the variables in a bash script.
To make thins easier to read, I will present solution in stages. From the OP test data, I created a file: test.xml
Parsing said XML in bash and extracting the data in 90 chars:
awk 'BEGIN { FS="<|>"; RS="\n" }; /host|username|password|dbname/ { print $2, $4 }' test.xml
I normally use more readable version since it is easier to modify in real life as I often need to test differently:
awk 'BEGIN { FS="<|>"; RS="\n" }; { if ($0 ~ /host|username|password|dbname/) print $2,$4}' test.xml
I do not care how is the format called. I seek only the simplest solution. In this particular case, I can see from the data that newline is the record separator (RS) and <> delimit fields (FS). In my original case, I had complicated indexing of 6 values within two records, relating them, find when the data exists plus fields (records) may or may not exist. It took 4 lines of awk to solve the problem perfectly. So, adapt idea to each need before using it!
Second part simply looks it there is wanted string in a line (RS) and if so, prints out needed fields (FS). The above took me about 30 seconds to copy and adapt from the last command I used this way (4 times longer). And that is it! Done in 90 chars.
But, I always need to get the data neatly into variables in my script. I first test the constructs like so:
awk 'BEGIN { FS="<|>"; RS="\n" }; { if ($0 ~ /host|username|password|dbname/) print $2"=\""$4"\"" }' test.xml
In some cases I use printf instead of print. When I see everything looks well, I simply finish assigning values to variables. I know many think "eval" is "evil", no need to comment :) Trick works perfectly on all four of my networks for years. But keep learning if you do not understand why this may be bad practice! Including bash variable assignments and ample spacing, my solution needs 120 chars to do everything.
eval $( awk 'BEGIN { FS="<|>"; RS="\n" }; { if ($0 ~ /host|username|password|dbname/) print $2"=\""$4"\"" }' test.xml ); echo "host: $host, username: $username, password: $password dbname: $dbname"
This works if you are wanting XML attributes:
$ cat alfa.xml
<video server="asdf.com" stream="H264_400.mp4" cdn="limelight"/>
$ sed 's.[^ ]*..;s./>..' alfa.xml > alfa.sh
$ . ./alfa.sh
$ echo "$stream"
H264_400.mp4
Source: Stackoverflow.com