matching a pattern in a file & prefixing a word

shivarajM · 04-29-2009, 02:11 PM

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.....

jschiwal · 04-29-2009, 02:13 PM

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.

esoukenka · 05-28-2009, 12:47 PM

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

sycamorex · 05-28-2009, 01:14 PM

If the replacement needs to take place only in lines containing the pattern 'aaa', you could try the following:

Code:

sed -e '/aaa/ s/^/#123/g' file

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?