Modifying a particular data in a line contained in File 

I have a file containing data:

systemname/userid/password/comment
systemname1/userid1/password1/comment1
systemname2/userid2/password2/comment2

I want to modify the "password" using script.

Something like this would do the trick:

Code:

sed '/userid/s/oldpasswd/newpasswd/' inputfile > tempfile && \
cp tempfile inputfile && \
rm tempfileWhere the /userid/ means that the sed statement will only replace (substitute) "oldpasswd" with "newpasswd" for the userid given and not any other.
 

Writing data in a text file at particular line 

I need to write value of variable $version at a particular line in a text file.
Line number is determined by another variable &line......I don't know how to do it in shell script.

Try something like this:

Code:
sed $line'{
a\
'$version'
}' filename
 

AWK Help- Writing Data into a File 

I need to maintain a AUDIT file in system for every incoming and outgoing file. For this I am trying to append a record by using the AWK every time the file arriving.

I have used the code as below.
AWK '{print "FILENAME IS", $1,"DATE IS", $2}' >> AUDITFILE.txt

$1 and $2 are global variables from the previous line of code.

The above one is waiting for some more input and I don't now how to close the command.

At the end AUDITFILE is creating with no records.

How to append the data into a file by using the AWK?

You can use echo instead of awk
echo "FILENAME IS $1 DATE IS $2" >> AUDITFILE.txt

Usage of awk is either on the output of a command like
echo FIRST SECOND|awk '{print $1 $2}'

Or on a file like

awk '{print $1 $2}' filename

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