executable file in C - c

Question

I tried to write a program in C that checks if a certain file is executable or not, if it is a shell script or a binary
<apue.h> is a header from the book Advanced Programming in the UNIX Environment
I don't think the approach is exactly right (if it's a shell script or binary). I think there is a more efficient solution. Which one do you think?
In addition, what other problems does the code have?
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <apue.h>
void checkIfFileExists(const char *fileName);
int main (int argc,char *argv[])
{
char *fileName = argv[1];
if (argc < 2 )
{
err_quit("File to check not specified\n");
return 0;
}
if (argc > 2 )
{
err_quit("Too many arguments\n");
return 0;
}
checkIfFileExists(fileName);
return 0;
}
void checkIfFileExists(const char *fileName)
{
if(!access( fileName, F_OK ))
{
if(!access( fileName, X_OK ))
{
printf("The file %s is an executable\n",fileName);
//check if the file is binary or shell script
}
else
{
printf("The file %s is not an executable\n",fileName);
}
}
else
{
err_quit("The file %s was not found\n",fileName);
}
}

Answer 1

You can use the stat methods,
#include <sys/stat.h>
...
struct stat myf;
stat(<file>,&mf);
if( mf.st_mode & S_IXUSR )
printf("execute");
The output is a bitmap from which you can extract the file permission info
look at https://www.gnu.org/software/libc/manual/html_node/Permission-Bits.html
for the permission define available.