Shell Programming and Scripting

Please help!

Input pattern, where ... could be any number of lines
struct A {
Blah1
Blah2
Blah3
...
} B;

output pattern
struct AB {
Blah1
Blah2
Blah3
...
};

I need help in extracting everything between { and }
if it would have been on a single line { \(.*\)} should have worked.

Code:

perl -0777 -pe 's/\A[^\{]*\{//s; s/\}.*?\{/\n/sg; s/\}[^\}]*\Z//s'

... assuming there is no nesting of braces. Put in a better separator than just a newline if you like. The \A and \Z patterns match beginning of file and end of file, respectively; the middle substitution is the meat of the program.

Thanks era, but I am not seeing expected output using perl command

$ perl -0777 -pe 's/\A[^\{]*\{//s; s/\}.*?\{/\n/sg; s/\}[^\}]*\Z//s' test

Blah1
Blah2
Blah3
...


So it looks like that your script is extracting everything between { and }


Is there any way that this can be cooked in sed?

I was thinking on the line of
sed -e "/^struct.*{.*/,/.*}.*/s/^struct[[:blank:]]*\(.*\)[[:blank:]]*{\(.*\)}\(.*\);/struct \1\3 {\2};/g

This is where I see problem in extracting multiline "\2" and "\3"

I know I am not an advance sed user, and it needs some N H kinda magic

You are contradicting yourself. If that's not what you want, then what do you want?

Probably it could, if you are handy with sed, but I would not go there. (I have, more times than I care to remember, but it's so much easier in Perl.)

As an aside, you don't need to specify leading and trailing .* wildcards; sed will find the requested pattern anywhere on the line anyway (and in fact you are making it a bit harder for it).

Code:

sed -n '/{/,/}/{
s/^[^{]*{//
s/}[^}]*$//
p
}'

But you said this is not what you want, so you will need to explain what you do want.

... or maybe

Code:

sed -n '/{/,/}/{
/{/d
/}/d
p
}'

would be more to your liking. Feel free to replace either { or } with some sort of separator, again.

era, thanks for these scripts.
Sorry about the confusing first comment.
I was tryingto get output pattern
struct AB {
Blah1
Blah2
Blah3
...
};

and in this process I was unable to extract and replace multiline pattern from input
struct A {
Blah1
Blah2
Blah3
...
} B;

even if I tweak my sed command to include \n
sed -e "/^struct.*{.*/,/.*}.*/s/^struct[[:blank:]]*\(.*\)[[:blank:]]*{\(.*\)}\(.*\);/struct \1\3 {\2};/g

As you can see that I am not proficient with multiline pattern handling, thats why I see sed experts help in this forum