Shell Programming and Scripting

I have a source text file that contains something like this:

Code:

<start_template>
bool function( void *<var_name> )
{
        // Blah Blah
}
</start_template>

Following is used to remove this template from source file.

Code:

template=$(sed -n -e '/<start_template>/,/<\/start_template>/{
/<start_template>/b
/<\/start_template>/b
p
}' template.tpl )

I can then display the template in all its true glory with crlf.

Code:

echo "$template"

bool function( void *<var_name> )
 {
         // Blah Blah
 }

Now I want to replace <var_name> with 'hello'

Code:

template=$(echo $template | sed -e "s/<var_name>/hello/g")

Works but all the CRLF's seem to have been removed!

Code:

echo "$template"
bool function( void *hello ){// Blah Blah}

Ok, so lets not do the replace, but just write the un modified template to another file
after a particular line that contains say 'insert after this line'

Code:

sed -i -e "/insert after this line/a\ `echo $template`" target_file.txt

Checking target_file.txt, the template has been inserted in the correct place but again cr/lf have been removed.

Code:

 'insert after this line'
bool function( void *hello ){// Blah Blah}

I'm kind of using this to learn sed as well as write a small utility for my one use. I hate giving up and I'm sure it can be done.

Anyone have any idea how I can keep cr/lf when I do the replace and the write
to the new file?

thanks in advance.

It's the shell that's doing it, not sed. Put quotes around it, i.e. template="$(stuff)" instead of template=$(stuff)

Instead of storing it to a variable and printing it back, why not let sed print to stdout instead? Otherwise you may at some inconvenient point discover the limitations on lengths of a shell variable on your system.

Need quotes around the template var to stop shell removing all white space, see change in red below:

Code:

template=$(echo "$template" | sed -e "s/<var_name>/hello/g")

Wow, thanks for that. Will give it a go tomorrow and let you both know how it goes.

Thanks for such a quick response.

---------- Post updated 11-05-10 at 12:32 PM ---------- Previous update was 11-04-10 at 11:20 PM ----------

Thanks all, template="$(stuff)" instead of template=$(stuff) works a treat for the replace however I'm still having issues with writing out template to new file after text 'insert after this line'

sed -i -e "/insert after this line/a\ `echo $template`" target_file.txt

Replaces crlf again, any ideas? I'm guessing its the placement of quotes again but having no luck finding where the issue is.

tks

Another way to replace the function name is:

Code:

awk '/<start_template>/{f=1}
f && /bool function/{sub("<var_name>","hello");f=0}
' sourcefile > newfile