Programming

Hi there,
I'm facing a problem running the tar command with the popen function.

Code:

FILE* fp = popen("tar czf - textfile","r")
// output

this program should give the output to the stdout. I don't know if it is possible and which function like fprint() etc. should I use.
I suppose that I should put the fp stream to a string so I can print it.
In the end it should be executed in this way:

Code:

./myprog > file1.tgz

Thanks in advance!

Stefano

popen returns a file pointer. You will have to read from this filepointer using something like fread or fgets. This will read the data pointed to by the pointer into a string. This can be then printed to standard output using any of the printf family.

And can I get the size of the stream?

You do not require the size of the stream. The size parameter in the fread/fgets only refers to the maximum number of bytes to be read at one go. If the EOF is reached before the max num is hit, then only those read before eof is reached will be returned. You can stop reading on getting EOF.

Just do:
while ((c=getc(fp)) != EOF) putc(c,stdout):
or something. Although I don't see the point of the program. You could simply run tar.