--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toys/posix/tee.c	Sat Aug 25 14:25:22 2012 -0500
@@ -0,0 +1,75 @@
+/* vi: set sw=4 ts=4:
+ *
+ * tee.c - cat to multiple outputs.
+ *
+ * Copyright 2008 Rob Landley <rob@landley.net>
+ *
+ * See http://www.opengroup.org/onlinepubs/009695399/utilities/tee.html
+
+USE_TEE(NEWTOY(tee, "ia", TOYFLAG_BIN))
+
+config TEE
+    bool "tee"
+    default y
+    help
+      usage: tee [-ai] [file...]
+
+      Copy stdin to each listed file, and also to stdout.
+      Filename "-" is a synonym for stdout.
+
+      -a	append to files.
+      -i	ignore SIGINT.
+*/
+
+#include "toys.h"
+
+DEFINE_GLOBALS(
+    void *outputs;
+)
+
+#define TT this.tee
+
+struct fd_list {
+    struct fd_list *next;
+    int fd;
+};
+
+// Open each output file, saving filehandles to a linked list.
+
+static void do_tee_open(int fd, char *name)
+{
+    struct fd_list *temp;
+
+    temp = xmalloc(sizeof(struct fd_list));
+    temp->next = TT.outputs;
+    temp->fd = fd;
+    TT.outputs = temp;
+}
+
+void tee_main(void)
+{
+    if (toys.optflags&2) signal(SIGINT, SIG_IGN);
+
+    // Open output files
+    loopfiles_rw(toys.optargs,
+		O_RDWR|O_CREAT|((toys.optflags&1)?O_APPEND:O_TRUNC), 0666, 0,
+		do_tee_open);
+
+    for (;;) {
+        struct fd_list *fdl;
+        int len;
+
+        // Read data from stdin
+        len = xread(0, toybuf, sizeof(toybuf));
+        if (len<1) break;
+
+        // Write data to each output file, plus stdout.
+        fdl = TT.outputs;
+        for (;;) {
+            if(len != writeall(fdl ? fdl->fd : 1, toybuf, len)) toys.exitval=1;
+            if (!fdl) break;
+            fdl = fdl->next;
+        }
+    }
+
+}