cat.c

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

int main(int argc,char *argv[])
{
    if(argc!=2)
    {
        fprintf(stderr,"too %s arguments\n",argc<2?"many":"few");
        return 1;
    }
    FILE *read =fopen(argv[1],"rb");
    if(!read)
    {
        fprintf(stderr,"file \"%s\" does not exist\n",argv[1]);
        return 1;
    }
    int ch=fgetc(read);
    while(!feof(read))
    {
        putchar(ch);
        ch=fgetc(read);
    }
    fclose(read);
    putchar('\n');
    return 0;
}