Shell Programming and Scripting

I am trying to find and replace the following line in log4j.xml:

<param name="ConversionPattern" value="[%d{ABSOLUTE},%c{1}] %m%n"/>

to

<param name="ConversionPattern" value="[%d{ABSOLUTE},%p,%c{1}] %m%n"/>

The problem here is that when I find the first string above using sed or grep, it returns more than one line that matches my string in the file log4j.xml. However, I only want to replace one line that matches my criteria. For example: The log file has the following tags:

<appender name="PAYMENTLOG" class="org.jboss.logging.appender.DailyRollingFileAppender">
<errorHandler class="org.jboss.logging.util.OnlyOnceErrorHandler"/>
<param name="File" value="${jboss.server.home.dir}/log/payment.log"/>
<param name="Append" value="true"/>
<param name="DatePattern" value=".yyyy-MM-dd"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="[%d{ABSOLUTE},%c{1}] %m%n"/>
</layout>
</appender>




<appender name="EMAIL" class="org.apache.log4j.net.SMTPAppender">
<param name="Threshold" value="ERROR"/>
<param name="From" value="jboss@dummy.com"/>
<param name="Subject" value="${hostname} - PRODUCTION ERROR: MIDDLE TIER"/>
<param name="BufferSize" value="10"/>
<layout class="org.apache.log4j.PatternLayout">
<param name="ConversionPattern" value="[%d{ABSOLUTE},%c{1}] %m%n"/>
</layout>
</appender>


Notice the strings in bold? I ONLY want the string to be replaced under the tag "PAYMENTLOG" but not the other. Please help me how to achieve this.

I suppose its the first occurence of the file and hence...

Code:

sed 's/SEARCH_STRING/REPLACE_STRING/1'  infile >> New_file

Code:

awk '/"PAYMENTLOG"/{++f}f==1 && /%d\{ABSOLUTE\}/{sub(/%c/,"%p,&"); print; f++; next}1' file

--
If you need to apply the code to all occurrences of "PAYMENTLOG" tags use:

Code:

awk '/"PAYMENTLOG"/{++f}f && /%d\{ABSOLUTE\}/{sub(/%c/,"%p,&"); print; f=0; next}1' file

Thanks guys!. I tried the following

sed -i 's/<param\ name=\"ConversionPattern\"\ value=\"\[%d{ABSOLUTE},%c{1}\]\ %m%n\"\/>/<param\ name=\"ConversionPattern\"\ value=\"\[%d{ABSOLUTE},%p,%c{1}\]\ %m%n\"\/>/1' log4j.xml

I expected it to change the first occurance but rather it replaced all the 3 ocurrances. Did I do it in a wrong way?

What I meant is that I tried the following :

sed -i 's/STRING1/STRING2/1' file_name


I expected it to replace the first occurrence of string 1 but it rather replaced all occurances. Please help!

You can use this format

sed -i '0,/STRING1/s//STRING2/' inputfile

That is the number 0 not the letter O.

Thanks Bubbajoe. I tried it but it failed with following error

"sed: -e expression #1, char 2: invalid usage of line address 0"