Shell Programming and Scripting

<c-param>
<param-name>Number</param-name>
<param-value>22</param-value>
<description>my house number</description>
</c-param>
<c-param>
<param-name>Address</param-name>
<param-value>XYZ</param-value>
<description>my house Address</description>
</c-param>

I have a file and inside that there are lines as above. only unique key is the param-name ie. Number
Now i need to change the value of this param ie need to increase by 1 everytime whenever i run my script.

I am not able to find a direct way. can anyone tell me what is the best way.

1) there are multiple <c-param> in a file
2) there are <param-name> in a file but "Number" is different for each tab eg Number in one and Address in other
3) Value 22 can be some where else too so i need to update specifically related to Number only

Please let me know what is the best way

If you have Python and you know the language, here's an alternative

Code:

import re,os
s = open("file").read()
stringtofind = "<param-name>Number</param-name>\n<param-value>(.*?)</param-value>"
pat = re.compile("%s" % stringtofind,re.M)
number = int(pat.findall(s)[0]) + 1
stringtosub = "<param-name>Number</param-name>\n<param-value>%d</param-value>" % number
replacement = re.sub(stringtofind,stringtosub,s)
open("temp","w").write(replacement)
os.rename("temp","file")

output:

Code:

<c-param>
<param-name>Number</param-name>
<param-value>23</param-value>
<description>my house number</description>
</c-param>
<c-param>
<param-name>Address</param-name>
<param-value>XYZ</param-value>
<description>my house Address</description>
</c-param>

Code:

awk -F"[<>]" ' 
{
if( $0 ~ "<param-name>Number" ) 
{print; getline;no=$3+1;sub($3,no,$0); print; } 
else print 
} ' file

Give a try on this ...
$1 is the filename entered through command line

(( x = $(sed -n '/<param-value>\([0-9]*\)</p' $1 | sed 's!\(<param-value>\)\([0-9]*\)\(</param-value>\)!\2!') + 1 ))
x="<param-value>$x</param-value>"
sed 's!\(<param-value>\)\([0-9]*\)\(</param-value>\)!'$x'! ' $1 >newxml
rm -f $1 && mv newxml $1

Thanks Guys
I found out the solution, it may not be short but its working fine perfectly,
if you any other shorter one let me know

# get the line no of unique parameter ie Number
lineNo=`grep -n Number $fileName | awk -F":" '{print $1}'`
# Next line no
lineNo=`expr $lineNo + 1`

# get the current value in next value
curValue=`sed -n "${lineNo}p" $fileName | awk -F">" '{print $2}' | awk -F"<" '{print $1}'`
nextValue=`expr $curValue + 1`

rm -f temp.xml
# replace in that line only, and create a new file as sed does not change in original fiel
sed "$lineNo s/$curValue/$nextValue/" $fileName > temp.xml
rm -f $fileName
mv temp.xml $fileName