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sed appending needed only after first instance

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# 1  
Old 02-14-2011
sed appending needed only after first instance
Hi,
Here is my piece of code used with sed in shell script:
Code:
sed -i '/<falsemodule-option>/ a\<LdapLogin>' myxmlfile

The problem that i am facing with the above is that in 'myxml' file i have mulitple instances of
Code:
<falsemodule-option>

so when i execute the above sed command, it is appending the
Code:
<LdapLogin>

after every instance of
Code:
<falsemodule-option>

Please can some one help me to know if there is a way where i can append the text only after the first instance of the
Code:
<falsemodule-option>

and not after every instance of the
Code:
<falsemodule-option>

Thanks
# 2  
Old 02-14-2011
This should work:

Code:
sed s:\<falsemodule-option\>:\<falsemodule-option\>\<LdapLogin\>: myxmlfile

# 3  
Old 02-14-2011
Code:
sed -i '0,/<falsemodule-option>/ a\<LdapLogin>' myxmlfile

# 4  
Old 02-14-2011
I haven't tried either of these, but:
Quote:
Originally Posted by 47shailesh
This should work:

Code:
sed s:\<falsemodule-option\>:\<falsemodule-option\>\<LdapLogin\>: myxmlfile

While I can see this working if the file is all on one line I would have thought the result is the same as the original poster's problem.

Quote:
Originally Posted by yinyuemi
Code:
sed -i '0,/<falsemodule-option>/ a\<LdapLogin>' myxmlfile

This will append <LdapLogin> after every line until the first <falsemodule-option>.

I've tried doing things like this before and found no solution in sed. You either have to do something like:
Code:
sed -n 0,/<falsemodule-option>/ p < file
echo <LdapLogin>
sed 0,/<falsemodule-option>/ d < file

or use another tool like awk. And I hate awk, so I wouldn't normally recommend it Smilie

Andrew
# 5  
Old 02-14-2011
Code:
sed '0,/<falsemodule-option>/ {
/<falsemodule-option>/a\<LdapLogin>
}' file

awk is also a good way to try:

Code:
awk '/<falsemodule-option>/{p++} /<falsemodule-option>/ && p==1 {$0= $0"\n<LdapLogin>"}1'

This User Gave Thanks to yinyuemi For This Post:
sunrexstar
# 6  
Old 02-14-2011
Quote:
Originally Posted by apmcd47
While I can see this working if the file is all on one line I would have thought the result is the same as the original poster's problem.
Yeah on multiple line code in my first reply will fail. However following appears to work in ksh:
Code:
sed '1s:\<falsemodule-option\>:\<falsemodule-option\>\<LdapLogin\>:'


EDIT: Checked this with example works only for line number specified Smilie .
Last edited by 47shailesh; 02-14-2011 at 05:41 PM.. Reason: correction
# 7  
Old 02-14-2011
Quote:
Originally Posted by sunrexstar
Hi,
Here is my piece of code used with sed in shell script:
Code:
sed -i '/<falsemodule-option>/ a\<LdapLogin>' myxmlfile

The problem that i am facing with the above is that in 'myxml' file i have mulitple instances of
Code:
<falsemodule-option>

so when i execute the above sed command, it is appending the
Code:
<LdapLogin>

after every instance of
Code:
<falsemodule-option>

Please can some one help me to know if there is a way where i can append the text only after the first instance of the
Code:
<falsemodule-option>

and not after every instance of the
Code:
<falsemodule-option>

Thanks


The following sed script will print in a loop after the first match:
Code:
sed '/pattern/{a\
new text here
:loop
n
b loop
}'

Or, using ed:
Code:
ed -s file <<'EOED'
/pattern/a
new text here
.
w
q
EOED

Greetings and regards to all,
Alister
Last edited by alister; 02-14-2011 at 06:56 PM.. Reason: Misunderstood problem.
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