1 files changed, 47 insertions, 0 deletions
diff --git a/doc/progs/cat.go b/doc/progs/cat.go
new file mode 100644
index 000000000..9f0b8d4a3
--- /dev/null
+++ b/doc/progs/cat.go
@@ -0,0 +1,47 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"./file"
+	"flag"
+	"fmt"
+	"os"
+)
+
+func cat(f *file.File) {
+	const NBUF = 512
+	var buf [NBUF]byte
+	for {
+		switch nr, er := f.Read(buf[:]); true {
+		case nr < 0:
+			fmt.Fprintf(os.Stderr, "cat: error reading from %s: %s\n", f.String(), er.String())
+			os.Exit(1)
+		case nr == 0: // EOF
+			return
+		case nr > 0:
+			if nw, ew := file.Stdout.Write(buf[0:nr]); nw != nr {
+				fmt.Fprintf(os.Stderr, "cat: error writing from %s: %s\n", f.String(), ew.String())
+				os.Exit(1)
+			}
+		}
+	}
+}
+
+func main() {
+	flag.Parse() // Scans the arg list and sets up flags
+	if flag.NArg() == 0 {
+		cat(file.Stdin)
+	}
+	for i := 0; i < flag.NArg(); i++ {
+		f, err := file.Open(flag.Arg(i))
+		if f == nil {
+			fmt.Fprintf(os.Stderr, "cat: can't open %s: error %s\n", flag.Arg(i), err)
+			os.Exit(1)
+		}
+		cat(f)
+		f.Close()
+	}
+}