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Find Key and replace value

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# 1  
Old 11-10-2015
Find Key and replace value
Hi,

I am new to shell scripting. I have a config file where key and value is stored as below. In my shell script, I want to look for Test ID in the config file and replace the value 1 with another value stored in a variable. How would I do that ?

Code:
<Config Key="Test ID" Value="1"/>

I would appreciate anybody's help on this.

Regards,
Vishvar
Last edited by Don Cragun; 11-10-2015 at 06:54 PM.. Reason: Add CODE and ICODE tags.
# 2  
Old 11-10-2015
Code:
sed 's/"Test ID" Value="1"/"Test ID" Value="2"/'

or:
Code:
sed 's/\("Test ID" Value=\)"1"/\1"2"/'


Code:
var="2"
sed "s/\"Test ID\" Value=\"1\"/\"Test ID\" Value=\"$var\"/"

or:
Code:
var="2"
sed "s/\(\"Test ID\" Value=\)\"1\"/\1\"$var\"/"

Last edited by Aia; 11-10-2015 at 11:26 AM..
# 3  
Old 11-10-2015
Hi Aia,

Thanks for reply. When I try to run after adding below line script just hangs, I am not getting even any error message. Is there any prerequisite to use sed?

Code:
sed "s/\"Test ID\" Value=\"1\"/\"Test ID\" Value=\"$var\"/"


Moreover the existing entry in the config file can be any of below such values. It is not always Value="1". So I can't replace as it is. I need to look for key "Test ID" and replace the corresponding value with my desired value whatever the old value is.


Code:
<Config Key="Test ID" Value="1"/>

or
Code:
<Config Key="Test ID" Value="1111"/>

or
Code:
<Config Key="Test ID" Value="abcdef"/>

Regards,
Vishnu
Last edited by Don Cragun; 11-10-2015 at 06:55 PM.. Reason: Add CODE and ICODE tags.
# 4  
Old 11-10-2015
What's the name of the file?
Please, try the following to accommodate your new divulged information. The @ is nothing more that custom delimiters for sed, instead of the default /, which might make it easier to differentiate from all those escapes
Code:
sed "s@\(Test ID\" Value=\"\).*\(\"\/>\)@\1$var\2@" Vishnuvardhanh.file

or perhaps this:
Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" Vishnuvardhanh.file

Last edited by Aia; 11-10-2015 at 01:41 PM..
# 5  
Old 11-10-2015
Hi Aia,

Below line helps, it prints the required result as output but does not actually update the config file.

Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml


Code:
var ="requiredval"

Output prints as below :
Code:
<Config Key="Test ID" Value="requiredval"/>

But still config.xml has old entry as below :
Code:
<Config Key="Test ID" Value="1"/>

---------- Post updated at 01:42 PM ---------- Previous update was at 01:26 PM ----------

Hi Aia,
Thanks a lot for your help.

Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml > tmp.xml && mv tmp.xml ais_config.xml

I moved updates to a temporary file and then moved to original config file, so now it replaced. You can always let me know if any easier way in performance wise.

Regards,
Vishvar
Last edited by Don Cragun; 11-10-2015 at 06:57 PM.. Reason: Add CODE and ICODE tags.
# 6  
Old 11-10-2015
Quote:
Originally Posted by Vishnuvardhanh
Hi Aia,

Below line helps, it prints the required result as output but does not actually update the config file.

sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml


var ="requiredval"
Output prints as below :
<Config Key="Test ID" Value="requiredval"/>

But still config.xml has old entry as below :
<Config Key="Test ID" Value="1"/>
Note: the highlighted red is to bring your attention that variables in the shell can not have spaces between the = symbol

Yes, sed would output the result to the STDOUT (standard output), normally your monitor or screen; it does not modify the file:
if you use the GNU sed this will change the file in place. Make sure the result is what you want.
Code:
sed -i "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml

Or you can redirect the output to a temporary file and then rename it to config.xml
Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml > temp.xml && mv temp.xml config.xml

---------- Post updated at 12:07 PM ---------- Previous update was at 11:49 AM ----------

Quote:
Originally Posted by Vishnuvardhanh
[...]

sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml > tmp.xml && mv tmp.xml ais_config.xml

I moved updates to a temporary file and then moved to original config file, so now it replaced. You can always let me know if any easier way in performance wise.
[...]
There is no need to create a tmp file and rename it if the output file is going to be different that the input file config.xml

Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml > ais_config.xml

That's the only "performance wise" modification I could tell you.
# 7  
Old 11-10-2015
Code:
sed -i "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml

This line creates an empty config.xml file though.

I am using second one and works fine.
Code:
sed "s@\(Test ID\" Value=\"\)[^\"]*\(\"\/>\)@\1$var\2@" config.xml > temp.xml && mv temp.xml config.xml

Thank you Aia ! Smilie
Last edited by Don Cragun; 11-10-2015 at 06:58 PM.. Reason: Add CODE tags.
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