implement cat gnu coreutil

coreutils/cat.c

@@ -0,0 +1,36 @@
+/* TODO:
+     1. read filename from argv[1]
+     2. write errors to stderr
+     3. open file for reading
+     4. character by character forward to stdout
+ */
+
+#include <stdio.h>
+
+#define MAX_LEN 500 
+
+int main(int argc, char *argv[]) {
+  FILE *file;
+  int c;
+  
+  fprintf(stderr, "cat <filename>\n");
+
+  if (argc != 2) {
+    fprintf(stderr, "ERROR: invalid input\n");
+    return -1;
+  }
+
+  file = fopen(argv[1], "r");
+  if (!file) {
+    fprintf(stderr, "ERROR: unable to open file\n");
+    return -1;
+  }
+
+  while ((c = fgetc(file)) != EOF) {
+    putc(c, stdout);
+  }
+
+  fprintf(stderr, "Completed forward to stdout");
+
+  return 0;
+}