new utilities.

the .C files compile but are renamed to avoid building automatically.

src/cmd/cat.c

@@ -0,0 +1,36 @@
+#include <u.h>
+#include <libc.h>
+
+void
+cat(int f, char *s)
+{
+	char buf[8192];
+	long n;
+
+	while((n=read(f, buf, (long)sizeof buf))>0)
+		if(write(1, buf, n)!=n)
+			sysfatal("write error copying %s: %r", s);
+	if(n < 0)
+		sysfatal("error reading %s: %r", s);
+}
+
+void
+main(int argc, char *argv[])
+{
+	int f, i;
+
+	argv0 = "cat";
+	if(argc == 1)
+		cat(0, "<stdin>");
+	else for(i=1; i<argc; i++){
+		f = open(argv[i], OREAD);
+		if(f < 0)
+			sysfatal("can't open %s: %r", argv[i]);
+		else{
+			cat(f, argv[i]);
+			close(f);
+		}
+	}
+	exits(0);
+}
+