Test input file's POSIX type

type_test.c

#include <sys/stat.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    struct stat st;
    
    if (stat(argv[1], &st) == -1) {
        fprintf(stderr, "Error: stat() failed\n");
        return EXIT_FAILURE;
    }
    
    switch (st.st_mode & S_IFMT) 
        {
        case S_IFBLK:  fprintf(stdout, "block device\n");            break;
        case S_IFCHR:  fprintf(stdout, "character device\n");        break;
        case S_IFDIR:  fprintf(stdout, "directory\n");               break;
        case S_IFIFO:  fprintf(stdout, "FIFO/pipe\n");               break;
        case S_IFLNK:  fprintf(stdout, "symlink\n");                 break;
        case S_IFREG:  fprintf(stdout, "regular file\n");            break;
        case S_IFSOCK: fprintf(stdout, "socket\n");                  break;
        default:       fprintf(stdout, "unknown?\n");                break;
        }
    
    return EXIT_SUCCESS;
}

Compiles with gcc -Wall type_test.c -o type_test

Sample run:

$ ./type_test <(cat makefile)
FIFO/pipe
$ ./type_test makefile
regular file