Index: usr.bin/sponge/Makefile
===================================================================
--- /dev/null
+++ usr.bin/sponge/Makefile
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+PROG=	sponge
+
+.include <bsd.prog.mk>
Index: usr.bin/sponge/sponge.1
===================================================================
--- /dev/null
+++ usr.bin/sponge/sponge.1
@@ -0,0 +1,60 @@
+.\"	Eitan Adler.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd November 01, 2017
+.Dt SPONGE 1
+.Os
+.Sh NAME
+.Nm sponge
+.Nd buffer stdin and write to stdout
+.Sh SYNOPSIS
+.Nm
+.Op Fl a
+.Ar filename
+.Sh DESCRIPTION
+The
+.Nm
+utility reads standard in until complete, and then opens
+the output file, and then writes to it.
+The following options are available:
+.Bl -tag -width indent
+.It Fl a
+Opens
+.Ar filename
+in append mode.
+.El
+.Sh SEE ALSO
+.Xr builtin 1 ,
+.Xr csh 1 ,
+.Xr getrusage 2 ,
+.Xr tee 1
+.Xr wait 2
+.Sh EXIT STATUS
+.Ex -std
+.Sh HISTORY
+A
+.Nm
+utility appeared in
+.At v3 .
Index: usr.bin/sponge/sponge.c
===================================================================
--- /dev/null
+++ usr.bin/sponge/sponge.c
@@ -0,0 +1,119 @@
+#include <assert.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#define DEFAULT_BUFF_SIZE 16384
+
+static int flag_append = 0;
+
+static void usage(void);
+static void* safe_malloc(size_t size);
+static void* safe_reallocf(void *ptr, size_t size);
+
+static void* safe_malloc(size_t size)
+{
+	void* ret;
+	ret = malloc(size);
+	if (ret == NULL)
+	{
+		perror("malloc failed");
+		exit(1);
+	}
+	return ret;
+}
+
+static void* safe_reallocf(void *ptr, size_t size)
+{
+	void* ret;
+	ret = reallocf(ptr, size);
+	if (ret == NULL)
+	{
+		perror("reallocf failed");
+		exit(1);
+	}
+	return ret;
+}
+
+static void
+usage(void)
+{
+	printf("usage: sponge [-a] filename\n");
+}
+
+int
+main(int argc, char* argv[])
+{
+	char* buf;
+	char* bufstart;
+	char* outfile;
+	char* openflags = "w";
+	size_t bufsize;
+	size_t bufused;
+	ssize_t i;
+	int opt;
+	FILE* fh;
+
+	while ((opt = getopt(argc, argv, "ah")) != -1)
+	{
+		switch (opt)
+		{
+			case 'a':
+				flag_append=1;
+				break;
+			case 'h':
+				usage();
+				exit(0);
+			default:
+				usage();
+				exit(1);
+		}
+	}
+
+	if (optind < argc)
+	{
+                outfile = argv[optind];
+	}
+
+
+	bufsize = DEFAULT_BUFF_SIZE;
+	bufused = 0;
+	bufstart = safe_malloc(bufsize);
+	buf = bufstart;
+
+	while ((i = read(STDIN_FILENO, buf, bufsize - bufused)) > 0) {
+		bufused += i;
+		if (bufused == bufsize)
+		{
+			bufsize *= 4;
+			bufstart = safe_reallocf(bufstart, bufsize);
+		}
+		buf = bufstart + bufused;
+	}
+
+	assert (buf != NULL);
+	assert (bufstart != NULL);
+
+	if (outfile)
+	{
+		if (flag_append)
+		{
+			openflags = "a";
+		}
+		fh = fopen(outfile, openflags);
+	}
+	else
+	{
+		fh = stdout;
+	}
+
+	if (fwrite(bufstart, bufused, 1, fh) < 0)
+	{
+		perror("error writing buf");
+		exit(1);
+	}
+	if (outfile)
+	{
+		fclose(fh);
+	}
+}
Index: usr.bin/tee/tee.1
===================================================================
--- usr.bin/tee/tee.1
+++ usr.bin/tee/tee.1
@@ -72,6 +72,8 @@
 except in the event of the
 .Fl i
 option.
+.Sh SEE ALSO
+.Xr sponge 1
 .Sh EXIT STATUS
 .Ex -std
 .Sh STANDARDS