Question

There has been an attempt at this question already, Detecting and concatenating a multi-line structure using sed, but none of the answers worked for my specific case.

I have a program written in c which has two kinds of multi-lined structures. I need to figure out how to use the unix utility sed to compress these structure definitions to a single line and then make two copies, so there are three copies of the structure definition in total.

Here is my c program example:

#include <stdio.h>
#include <stdlib.h>

struct node {
    int val;
    struct node *next;
};

typedef struct {
    int numer;
    int denom;
} Rational;

int main()
{
    struct node head;
    Rational half, *newf = malloc(sizeof(Rational));

    head = (struct node){ 5, NULL };
    half = (Rational){ 1, 2 };
    *newf = (Rational){ 2, 3 };

    return 0;
}

I know that the sed command will look something to the extent of sed '/ *struct .*/N;' test.c to find the structure and then a branch statement to append the rest of the lines of the structure definition to the single line.

Answer 1

Here’s how to do it. Have a file which calls sed -f and then create a file with a list of sed commands. The file goes as follows.

/typedef struct/b a
/^struct.*{/!b;:a;N
/}/!b a;p
s/\n//g