How to get the path to the current file (pwd) in Linux from C?

Question

I\'d like to know if it is somehow possible to run system("pwd") on the current DIR. So for example let\'s have this folder structure:

exam         


        

Answer 1

How to not hardcode the path length with pathconf

I believe this is the correct way to do it:

#define _XOPEN_SOURCE 700
#include 
#include 
#include 
#include 

int main(void) {
    long n;
    char *buf;

    n = pathconf(".", _PC_PATH_MAX);
    assert(n != -1);
    buf = malloc(n * sizeof(*buf));
    assert(buf);
    if (getcwd(buf, n) == NULL) {
        perror("getcwd");
        exit(EXIT_FAILURE);
    } else {
        printf("%s\n", buf);
    }
    free(buf);
    return EXIT_SUCCESS;
}

GitHub upstream.

Compile and run:

gcc -Wall -Wextra -std=c11 -pedantic-errors  -o getcwd.out getcwd.c
./getcwd.out

POSIX describes _PC_PATH_MAX it as:

The value returned for the variable {PATH_MAX} indicates the longest relative pathname that could be given if the specified directory is the process' current working directory. A process may not always be able to generate a name that long and use it if a subdirectory in the pathname crosses into a more restrictive file system.

Tested on Ubuntu 18.10, n == 4096 in this implementation.