How to copy and paste line in shell script

[upsrk]

Hi

I want to grep for a line and copy and paste that line.

for Example

---- file abc.txt ----
host=atlx1 sid=atld1 mail=abc@abc.com
host=atlx2 sid=atld2 mail=xyz@abc.com
host=atlx3 sid=atld3 mail=def@abc.com
host=atlx4 sid=atld4 mail=mno@abc.com
--- end of file abc.txt ----

Now I want to grep line with host=atlx3 and sid=atld3 and copy and paste the line and ALSO put "#" in front of one of the line. The following is the output I would like to see...

---- file output.txt ----
host=atlx1 sid=atld1 mail=abc@abc.com
host=atlx2 sid=atld2 mail=xyz@abc.com
#host=atlx3 sid=atld3 mail=def@abc.com
host=atlx3 sid=atld3 mail=def@abc.com
host=atlx4 sid=atld4 mail=mno@abc.com
--- end of file output.txt ----

How can I do this in shell script.

Thanks in advance for your help.

RK

[radoulov]

awk>output.txt '/host=atlx3 sid=atld3/{print "#"$0}1' abc.txt

[scm]

Or

sed 's/host=atlx3 sid=atld3.*/#&/' abc.txt >output.txt

Less to type, and you can use the -i flag and drop the output redirect to make the change straight to the input file.

Interesting that neither of the solutions uses the asked-for grep, since that's an inappropriate tool for this problem.