matching a pattern in a file & prefixing a word
 

Hi,

In my shell script i have to match a patten in a file , if found i have to prefix the entair line by a "word"

eg. pattern = "aaa" prefix= #123
file: bbbb xxx
zzzz aaaa
qqqq kkkk

outPut file: bbbb xxx
#123zzzz aaaa
qqqq kkkk


Waiting your precious reply.....

Look into using sed. The -i option will allow you to do inplace editing making changes in the original file.

You might not to do this until your sed command is tested.

sed
 

Yes sed is what you want.

Test this on your file

sed -e 's/^aaa/wordaaa/g' ../lyrics

This command will replace all lines starting with aaa to wordaaa. Remove the ^ to do them all.

that will not modify file to do that use the -i option

If the replacement needs to take place only in lines containing the pattern 'aaa', you could try the following:
It will insert '#123' at the beginning of each line containing the pattern 'aaa'
As it was mentioned before, you need to use the switch -i to actually modify the file.
HTH
edit: hope it's not your homework, is it?