Question

Is there a POSIX function that will give me the size of a directory (including all sub-folders), roughly equivalent to ‘du -s somepath‘?

Answer 1

$ man nftw 

NAME

ftw, nftw – file tree walk

DESCRIPTION

ftw() walks through the directory tree that is located under the directory dirpath, and calls fn() once for each entry in the tree. By default, directories are handled before the files and subdirectories they contain (pre-order traversal).

CONFORMING TO

POSIX.1-2001, SVr4, SUSv1.

Simple example

#include <stdio.h> #include <errno.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h>  static unsigned int total = 0;  int sum(const char *fpath, const struct stat *sb, int typeflag) {     total += sb->st_size;     return 0; }  int main(int argc, char **argv) {     if (!argv[1] || access(argv[1], R_OK)) {         return 1;     }     if (ftw(argv[1], &sum, 1)) {         perror('ftw');         return 2;     }     printf('%s: %u\n', argv[1], total);     return 0; }