diff --git a/Makefile b/Makefile
index bca2cb2..a79f530 100644
--- a/Makefile
+++ b/Makefile
@@ -38,6 +38,7 @@ SRC = \
 	chroot.c   \
 	cksum.c    \
 	cmp.c      \
+	col.c      \
 	cols.c     \
 	comm.c     \
 	cp.c       \
diff --git a/col.1 b/col.1
new file mode 100644
index 0000000..312fd49
--- /dev/null
+++ b/col.1
@@ -0,0 +1,126 @@
+.\"	$OpenBSD: src/usr.bin/col/col.1,v 1.11 2010/10/29 07:58:04 jmc Exp $
+.\"	$NetBSD: col.1,v 1.4 1995/03/26 05:25:52 glass Exp $
+.\"
+.\" Copyright (c) 1990, 1993
+.\"	The Regents of the University of California.  All rights reserved.
+.\"
+.\" This code is derived from software contributed to Berkeley by
+.\" Michael Rendell.
+.\"
+.\" 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.
+.\" 3. Neither the name of the University nor the names of its contributors
+.\"    may be used to endorse or promote products derived from this software
+.\"    without specific prior written permission.
+.\"
+.\" 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.
+.\"
+.\"     @(#)col.1	8.1 (Berkeley) 6/29/93
+.\"
+.Dd $Mdocdate: May 31 2007 $
+.Dt COL 1
+.Os
+.Sh NAME
+.Nm col
+.Nd filter reverse line feeds and backspaces from input
+.Sh SYNOPSIS
+.Nm col
+.Op Fl bfhx
+.Op Fl l Ar num
+.Sh DESCRIPTION
+.Nm
+filters out reverse (and half-reverse) line feeds so that the output is
+in the correct order with only forward and half-forward line
+feeds, and replaces whitespace characters with tabs where possible.
+.Pp
+.Nm
+reads from the standard input and writes to the standard output.
+.Pp
+The options are as follows:
+.Bl -tag -width Ds
+.It Fl b
+Do not output any backspaces, printing only the last character
+written to each column position.
+This can be useful in processing the output of
+.Xr mandoc 1 .
+.It Fl f
+Forward half-line feeds are permitted
+.Pf ( Ns Dq fine
+mode).
+Normally characters printed on a half-line boundary are printed
+on the following line.
+.It Fl h
+Compress spaces into tabs.
+This is the default behavior.
+.It Fl l Ar num
+Buffer at least
+.Ar num
+lines in memory.
+By default, 128 lines are buffered.
+.It Fl x
+Output multiple spaces instead of tabs.
+.El
+.Pp
+The control sequences for carriage motion that
+.Nm
+understands and their decimal values are listed in the following
+table:
+.Pp
+.Bl -tag -width "carriage return" -compact
+.It ESC\-7
+Reverse line feed (escape then 7).
+.It ESC\-10
+Half reverse line feed (escape then 10).
+.It ESC\-11
+Half forward line feed (escape then 11).
+.It backspace
+Moves back one column (8); ignored in the first column.
+.It carriage return
+(13)
+.It newline
+Forward line feed (10); also does carriage return.
+.It shift in
+Shift to normal character set (15).
+.It shift out
+Shift to alternate character set (14).
+.It space
+Moves forward one column (32).
+.It tab
+Moves forward to next tab stop (9).
+.It vertical tab
+Reverse line feed (11).
+.El
+.Pp
+All unrecognized control characters and escape sequences are
+discarded.
+.Pp
+.Nm
+keeps track of the character set as characters are read and makes
+sure the character set is correct when they are output.
+.Pp
+If the input attempts to back up to the last flushed line,
+.Nm
+will display a warning message.
+.Sh SEE ALSO
+.Xr expand 1
+.Sh HISTORY
+A
+.Nm
+command appeared in
+.At v6 .
diff --git a/col.c b/col.c
new file mode 100644
index 0000000..fb3d1a6
--- /dev/null
+++ b/col.c
@@ -0,0 +1,507 @@
+/*	$OpenBSD: src/usr.bin/col/col.c,v 1.11 2009/10/27 23:59:36 deraadt Exp $	*/
+/*	$NetBSD: col.c,v 1.7 1995/09/02 05:48:50 jtc Exp $	*/
+
+/*-
+ * Copyright (c) 1990, 1993, 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Michael Rendell of the Memorial University of Newfoundland.
+ *
+ * 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.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * 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.
+ */
+
+#include <ctype.h>
+#include <err.h>
+#include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+
+#include "util.h"
+
+#define	BS	'\b'		/* backspace */
+#define	TAB	'\t'		/* tab */
+#define	SPACE	' '		/* space */
+#define	NL	'\n'		/* newline */
+#define	CR	'\r'		/* carriage return */
+#define	ESC	'\033'		/* escape */
+#define	SI	'\017'		/* shift in to normal character set */
+#define	SO	'\016'		/* shift out to alternate character set */
+#define	VT	'\013'		/* vertical tab (aka reverse line feed) */
+#define	RLF	'\007'		/* ESC-07 reverse line feed */
+#define	RHLF	'\010'		/* ESC-010 reverse half-line feed */
+#define	FHLF	'\011'		/* ESC-011 forward half-line feed */
+
+/* build up at least this many lines before flushing them out */
+#define	BUFFER_MARGIN		32
+
+typedef char CSET;
+
+typedef struct char_str {
+#define	CS_NORMAL	1
+#define	CS_ALTERNATE	2
+	short		c_column;	/* column character is in */
+	CSET		c_set;		/* character set (currently only 2) */
+	char		c_char;		/* character in question */
+} CHAR;
+
+typedef struct line_str LINE;
+struct line_str {
+	CHAR	*l_line;		/* characters on the line */
+	LINE	*l_prev;		/* previous line */
+	LINE	*l_next;		/* next line */
+	int	l_lsize;		/* allocated sizeof l_line */
+	int	l_line_len;		/* strlen(l_line) */
+	int	l_needs_sort;		/* set if chars went in out of order */
+	int	l_max_col;		/* max column in the line */
+};
+
+LINE   *alloc_line(void);
+void	dowarn(int);
+void	flush_line(LINE *);
+void	flush_lines(int);
+void	flush_blanks(void);
+void	free_line(LINE *);
+void	usage(void);
+void   *xmalloc(void *, size_t);
+
+CSET	last_set;		/* char_set of last char printed */
+LINE   *lines;
+int	compress_spaces;	/* if doing space -> tab conversion */
+int	fine;			/* if `fine' resolution (half lines) */
+int	max_bufd_lines;		/* max # lines to keep in memory */
+int	nblank_lines;		/* # blanks after last flushed line */
+int	no_backspaces;		/* if not to output any backspaces */
+
+#define	PUTC(ch) \
+	if (putchar(ch) == EOF) \
+		eprintf("stdout:");
+
+int
+main(int argc, char *argv[])
+{
+	int ch;
+	CHAR *c;
+	CSET cur_set;			/* current character set */
+	LINE *l;			/* current line */
+	int extra_lines;		/* # of lines above first line */
+	int cur_col;			/* current column */
+	int cur_line;			/* line number of current position */
+	int max_line;			/* max value of cur_line */
+	int this_line;			/* line l points to */
+	int nflushd_lines;		/* number of lines that were flushed */
+	int adjust, warned;
+
+	max_bufd_lines = 128;
+	compress_spaces = 1;		/* compress spaces into tabs */
+	ARGBEGIN {
+	case 'b':		/* do not output backspaces */
+		no_backspaces = 1;
+		break;
+	case 'f':		/* allow half forward line feeds */
+		fine = 1;
+		break;
+	case 'h':		/* compress spaces into tabs */
+		compress_spaces = 1;
+		break;
+	case 'l':		/* buffered line count */
+		max_bufd_lines = estrtol(EARGF(usage()), 0);
+		break;
+	case 'x':		/* do not compress spaces into tabs */
+		compress_spaces = 0;
+		break;
+	case '?':
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc != 0)
+		usage();
+
+	/* this value is in half lines */
+	max_bufd_lines *= 2;
+
+	adjust = cur_col = extra_lines = warned = 0;
+	cur_line = max_line = nflushd_lines = this_line = 0;
+	cur_set = last_set = CS_NORMAL;
+	lines = l = alloc_line();
+
+	while ((ch = getchar()) != EOF) {
+		if (!isgraph(ch)) {
+			switch (ch) {
+			case BS:		/* can't go back further */
+				if (cur_col == 0)
+					continue;
+				--cur_col;
+				continue;
+			case CR:
+				cur_col = 0;
+				continue;
+			case ESC:		/* just ignore EOF */
+				switch(getchar()) {
+				case RLF:
+					cur_line -= 2;
+					break;
+				case RHLF:
+					cur_line--;
+					break;
+				case FHLF:
+					cur_line++;
+					if (cur_line > max_line)
+						max_line = cur_line;
+				}
+				continue;
+			case NL:
+				cur_line += 2;
+				if (cur_line > max_line)
+					max_line = cur_line;
+				cur_col = 0;
+				continue;
+			case SPACE:
+				++cur_col;
+				continue;
+			case SI:
+				cur_set = CS_NORMAL;
+				continue;
+			case SO:
+				cur_set = CS_ALTERNATE;
+				continue;
+			case TAB:		/* adjust column */
+				cur_col |= 7;
+				++cur_col;
+				continue;
+			case VT:
+				cur_line -= 2;
+				continue;
+			}
+			continue;
+		}
+
+		/* Must stuff ch in a line - are we at the right one? */
+		if (cur_line != this_line - adjust) {
+			LINE *lnew;
+			int nmove;
+
+			adjust = 0;
+			nmove = cur_line - this_line;
+			if (!fine) {
+				/* round up to next line */
+				if (cur_line & 1) {
+					adjust = 1;
+					nmove++;
+				}
+			}
+			if (nmove < 0) {
+				for (; nmove < 0 && l->l_prev; nmove++)
+					l = l->l_prev;
+				if (nmove) {
+					if (nflushd_lines == 0) {
+						/*
+						 * Allow backup past first
+						 * line if nothing has been
+						 * flushed yet.
+						 */
+						for (; nmove < 0; nmove++) {
+							lnew = alloc_line();
+							l->l_prev = lnew;
+							lnew->l_next = l;
+							l = lines = lnew;
+							extra_lines++;
+						}
+					} else {
+						if (!warned++)
+							dowarn(cur_line);
+						cur_line -= nmove;
+					}
+				}
+			} else {
+				/* may need to allocate here */
+				for (; nmove > 0 && l->l_next; nmove--)
+					l = l->l_next;
+				for (; nmove > 0; nmove--) {
+					lnew = alloc_line();
+					lnew->l_prev = l;
+					l->l_next = lnew;
+					l = lnew;
+				}
+			}
+			this_line = cur_line + adjust;
+			nmove = this_line - nflushd_lines;
+			if (nmove >= max_bufd_lines + BUFFER_MARGIN) {
+				nflushd_lines += nmove - max_bufd_lines;
+				flush_lines(nmove - max_bufd_lines);
+			}
+		}
+		/* grow line's buffer? */
+		if (l->l_line_len + 1 >= l->l_lsize) {
+			int need;
+
+			need = l->l_lsize ? l->l_lsize * 2 : 90;
+			l->l_line = xmalloc((void *) l->l_line,
+			     need * sizeof(CHAR));
+			l->l_lsize = need;
+		}
+		c = &l->l_line[l->l_line_len++];
+		c->c_char = ch;
+		c->c_set = cur_set;
+		c->c_column = cur_col;
+		/*
+		 * If things are put in out of order, they will need sorting
+		 * when it is flushed.
+		 */
+		if (cur_col < l->l_max_col)
+			l->l_needs_sort = 1;
+		else
+			l->l_max_col = cur_col;
+		cur_col++;
+	}
+	if (max_line == 0)
+		exit(EXIT_SUCCESS);	/* no lines, so just exit */
+
+	/* goto the last line that had a character on it */
+	for (; l->l_next; l = l->l_next)
+		this_line++;
+	flush_lines(this_line - nflushd_lines + extra_lines + 1);
+
+	/* make sure we leave things in a sane state */
+	if (last_set != CS_NORMAL)
+		PUTC('\017');
+
+	/* flush out the last few blank lines */
+	nblank_lines = max_line - this_line;
+	if (max_line & 1)
+		nblank_lines++;
+	else if (!nblank_lines)
+		/* missing a \n on the last line? */
+		nblank_lines = 2;
+	flush_blanks();
+	exit(EXIT_SUCCESS);
+}
+
+void
+flush_lines(int nflush)
+{
+	LINE *l;
+
+	while (--nflush >= 0) {
+		l = lines;
+		lines = l->l_next;
+		if (l->l_line) {
+			flush_blanks();
+			flush_line(l);
+		}
+		nblank_lines++;
+		if (l->l_line)
+			(void)free((void *)l->l_line);
+		free_line(l);
+	}
+	if (lines)
+		lines->l_prev = NULL;
+}
+
+/*
+ * Print a number of newline/half newlines.  If fine flag is set, nblank_lines
+ * is the number of half line feeds, otherwise it is the number of whole line
+ * feeds.
+ */
+void
+flush_blanks(void)
+{
+	int half, i, nb;
+
+	half = 0;
+	nb = nblank_lines;
+	if (nb & 1) {
+		if (fine)
+			half = 1;
+		else
+			nb++;
+	}
+	nb /= 2;
+	for (i = nb; --i >= 0;)
+		PUTC('\n');
+	if (half) {
+		PUTC('\033');
+		PUTC('9');
+		if (!nb)
+			PUTC('\r');
+	}
+	nblank_lines = 0;
+}
+
+/*
+ * Write a line to stdout taking care of space to tab conversion (-h flag)
+ * and character set shifts.
+ */
+void
+flush_line(LINE *l)
+{
+	CHAR *c, *endc;
+	int nchars, last_col, this_col;
+
+	last_col = 0;
+	nchars = l->l_line_len;
+
+	if (l->l_needs_sort) {
+		static CHAR *sorted;
+		static int count_size, *count, i, save, sorted_size, tot;
+
+		/*
+		 * Do an O(n) sort on l->l_line by column being careful to
+		 * preserve the order of characters in the same column.
+		 */
+		if (l->l_lsize > sorted_size) {
+			sorted_size = l->l_lsize;
+			sorted = xmalloc((void *)sorted,
+			    sizeof(CHAR) * sorted_size);
+		}
+		if (l->l_max_col >= count_size) {
+			count_size = l->l_max_col + 1;
+			count = xmalloc((void *)count,
+			    sizeof(int) * count_size);
+		}
+		memset((char *)count, 0, sizeof(int) * l->l_max_col + 1);
+		for (i = nchars, c = l->l_line; --i >= 0; c++)
+			count[c->c_column]++;
+
+		/*
+		 * calculate running total (shifted down by 1) to use as
+		 * indices into new line.
+		 */
+		for (tot = 0, i = 0; i <= l->l_max_col; i++) {
+			save = count[i];
+			count[i] = tot;
+			tot += save;
+		}
+
+		for (i = nchars, c = l->l_line; --i >= 0; c++)
+			sorted[count[c->c_column]++] = *c;
+		c = sorted;
+	} else
+		c = l->l_line;
+	while (nchars > 0) {
+		this_col = c->c_column;
+		endc = c;
+		do {
+			++endc;
+		} while (--nchars > 0 && this_col == endc->c_column);
+
+		/* if -b only print last character */
+		if (no_backspaces)
+			c = endc - 1;
+
+		if (this_col > last_col) {
+			int nspace = this_col - last_col;
+
+			if (compress_spaces && nspace > 1) {
+				int ntabs;
+
+				ntabs = ((last_col % 8) + nspace) / 8;
+				if (ntabs) {
+					nspace -= (ntabs * 8) - (last_col % 8);
+					while (--ntabs >= 0)
+						PUTC('\t');
+				}
+			}
+			while (--nspace >= 0)
+				PUTC(' ');
+			last_col = this_col;
+		}
+		last_col++;
+
+		for (;;) {
+			if (c->c_set != last_set) {
+				switch (c->c_set) {
+				case CS_NORMAL:
+					PUTC('\017');
+					break;
+				case CS_ALTERNATE:
+					PUTC('\016');
+				}
+				last_set = c->c_set;
+			}
+			PUTC(c->c_char);
+			if (++c >= endc)
+				break;
+			PUTC('\b');
+		}
+	}
+}
+
+#define	NALLOC 64
+
+static LINE *line_freelist;
+
+LINE *
+alloc_line(void)
+{
+	LINE *l;
+	int i;
+
+	if (!line_freelist) {
+		l = xmalloc(NULL, sizeof(LINE) * NALLOC);
+		line_freelist = l;
+		for (i = 1; i < NALLOC; i++, l++)
+			l->l_next = l + 1;
+		l->l_next = NULL;
+	}
+	l = line_freelist;
+	line_freelist = l->l_next;
+
+	memset(l, 0, sizeof(LINE));
+	return (l);
+}
+
+void
+free_line(LINE *l)
+{
+
+	l->l_next = line_freelist;
+	line_freelist = l;
+}
+
+void *
+xmalloc(void *p, size_t size)
+{
+
+	if (!(p = realloc(p, size)))
+		eprintf("realloc:");
+	return (p);
+}
+
+void
+usage(void)
+{
+	eprintf("usage: %s [-bfhx] [-l num]\n", argv0);
+}
+
+void
+dowarn(int line)
+{
+	warnx("warning: can't back up %s",
+		line < 0 ? "past first line" : "-- line already flushed");
+}