argv[0] vs /proc/self/exe

self.c

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

int main(int argc, char *argv[]) {
    char *executable_path;

    executable_path = realpath(argv[0], NULL);
    if (executable_path == NULL) {
        perror("realpath");
        return EXIT_FAILURE;
    }

    printf("argv[0] realpath:\t\t%s\n", executable_path);
    free(executable_path);

    executable_path = realpath("/proc/self/exe", NULL);
    if (executable_path == NULL) {
        perror("realpath");
        return EXIT_FAILURE;
    }

    printf("/proc/self/exe realpath:\t%s\n", executable_path);
    free(executable_path);
    
    return EXIT_SUCCESS;
}

/*
 * Build with: gcc self.c -o self
 *
 * Example of running this on Ubuntu:
 *
 * $ /self
 * argv[0] realpath:		/tmp/self
 * /proc/self/exe realpath:	/tmp/self
 *
 * $ /lib64/ld-linux-x86-64.so.2 ./self
 * argv[0] realpath:		/tmp/self
 * /proc/self/exe realpath:	/usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
 *
 * Example of running this on Alpine:
 *
 * $ ./self
 * argv[0] realpath:		/tmp/self
 * /proc/self/exe realpath:	/tmp/self
 *
 * $ /lib/ld-musl-x86_64.so.1 ./self
 * argv[0] realpath:		/tmp/self
 * /proc/self/exe realpath:	/lib/ld-musl-x86_64.so.1
 *
 */