Merge Binary Files

I have a program that creates multiple binary files. The problem is that I need to merge the files together. I can use the cat command afterwards and merge the files by hand. I would like however to merge the files together in the C program. I know I could just read in and write, but that sounds wasteful as cat seems to work much faster. Any help as usual appreciated.

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I know I could just read in and write

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That's the right way.

probably cat works faster because it reads/writes in big chunks

I think fgets() and fputs() is good for this case.

No, fgets() and fputs() aren't binary-safe.

You mean, fread() and fwrite() :)

cat _DOES_ fread/fwrite (or some variant thereof) - so, yes, it doesn't make much sense to write your own version of the same functionality.

If you still want to do that, use large buffers for the read/write data - 4KB or bigger will be a good start.

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Mats

A buffer size of BUFSIZ is meant to have pretty good performance characteristics (on average).

cat may use the lower level read/write primitives which are a bit closer to the machine than the truly portable fread/fwrite. But you limit yourself to POSIX systems in doing so.

You also have to weigh the efficiency of cat with the cost of spawning another process.

Thanks for the help guys. This was a programing assignment designed to learn system calls on a unix based system. Therefore, I decided to use the system("cat -u ....") command.