diff --git a/utils/.gitignore b/utils/.gitignore
index 96c0cdb3..f1f0b59f 100644
--- a/utils/.gitignore
+++ b/utils/.gitignore
@@ -32,6 +32,7 @@ memstat
 mkdir
 mktemp
 mv
+nl
 pager
 passwd
 ps
diff --git a/utils/Makefile b/utils/Makefile
index f6087ddc..032db7fc 100644
--- a/utils/Makefile
+++ b/utils/Makefile
@@ -43,6 +43,7 @@ memstat \
 mkdir \
 mktemp \
 mv \
+nl \
 pager \
 passwd \
 ps \
diff --git a/utils/nl.c b/utils/nl.c
new file mode 100644
index 00000000..0cb8991a
--- /dev/null
+++ b/utils/nl.c
@@ -0,0 +1,422 @@
+/*
+ * Copyright (c) 2021 Jonas 'Sortie' Termansen.
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * nl.c
+ * Number lines.
+ */
+
+#include <err.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <regex.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+enum format
+{
+	LN,
+	RN,
+	RZ,
+};
+
+struct style
+{
+	char c;
+	regex_t regex;
+};
+
+static char delim[] = "\\:\\:\\:";
+static off_t initial = 1;
+static off_t increment = 1;
+static bool restart = false;
+static off_t blank_join = 1;
+static enum format format = RN;
+static int width = 6;
+static const char* separator = "\t";
+static struct style styles[] =
+{
+	{.c = 'n'},
+	{.c = 't'},
+	{.c = 'n'},
+};
+
+static off_t line_number;
+static size_t state = 1;
+static off_t blanks = 0;
+
+static bool nl(FILE* fp, const char* path)
+{
+	char* line = NULL;
+	size_t line_size = 0;
+	ssize_t line_length;
+	while ( 0 < (line_length = getline(&line, &line_size, fp)) )
+	{
+		if ( line[line_length - 1] == '\n' )
+			line[--line_length] = '\0';
+		bool error = false;
+		if ( delim[0] && !strcmp(line, delim) )
+		{
+			state = 0;
+			if ( restart )
+				line_number = initial;
+			error = printf("\n") == EOF;
+		}
+		else if ( delim[0] && !strcmp(line, delim + 2) )
+		{
+			state = 1;
+			error = printf("\n") == EOF;
+		}
+		else if ( delim[0] && !strcmp(line, delim + 4) )
+		{
+			state = 2;
+			error = printf("\n") == EOF;
+		}
+		else
+		{
+			const struct style* style = &styles[state];
+			bool counts =
+				style->c == 'a' ||
+				(style->c == 't' && strcmp(line, "") != 0) ||
+				(style->c == 'p' && !regexec(&style->regex, line, 0, NULL, 0));
+			if ( counts )
+			{
+				if ( !strcmp(line, "") )
+				{
+					blanks++;
+					if ( blank_join <= blanks )
+						blanks = 0;
+					else
+						counts = false;
+				}
+				else
+					blanks = 0;
+			}
+			if ( counts )
+			{
+				switch ( format )
+				{
+				case LN:
+					error = printf("%-*ji%s%s\n", width, (intmax_t) line_number,
+					               separator, line) == EOF;
+					break;
+				case RN:
+					error = printf("%*ji%s%s\n", width, (intmax_t) line_number,
+					               separator, line) == EOF;
+					break;
+				case RZ:
+					error = printf("%0*ji%s%s\n", width, (intmax_t) line_number,
+					               separator, line) == EOF;
+					break;
+				}
+				line_number += increment;
+			}
+			else
+				error = printf("%*s %s\n", width, "", line) == EOF;
+		}
+		if ( error )
+		{
+			warn("stdout");
+			free(line);
+			return false;
+		}
+	}
+	free(line);
+	if ( ferror(fp) )
+	{
+		warn("%s", path);
+		return false;
+	}
+	return true;
+}
+
+static bool nl_path(const char* path)
+{
+	if ( !strcmp(path, "-") )
+		return nl(stdin, path);
+	FILE* fp = fopen(path, "r");
+	if ( !fp )
+	{
+		warn("%s", path);
+		return false;
+	}
+	bool ret = nl(fp, path);
+	fclose(fp);
+	return ret;
+}
+
+static void compact_arguments(int* argc, char*** argv)
+{
+	for ( int i = 0; i < *argc; i++ )
+	{
+		while ( i < *argc && !(*argv)[i] )
+		{
+			for ( int n = i; n < *argc; n++ )
+				(*argv)[n] = (*argv)[n+1];
+			(*argc)--;
+		}
+	}
+}
+
+static void set_style(struct style* style, const char* string, const char* opt)
+{
+	if ( style->c == 'p' )
+		regfree(&style->regex);
+	if ( !strcmp(string, "a") || !strcmp(string, "t") || !strcmp(string, "n") )
+		style->c = string[0];
+	else if ( string[0] == 'p' || string[0] == 'E' )
+	{
+		int error = regcomp(&style->regex, string + 1,
+		                    string[0] == 'E' ? REG_EXTENDED : 0);
+		if ( error )
+		{
+			size_t size = regerror(error, NULL, NULL, 0);
+			char* error_string = malloc(size);
+			if ( !error_string )
+				errx(1, "%s: Invalid regular expression: %s", opt, string);
+			regerror(error, NULL, error_string, size);
+			errx(1, "%s: %s: %s", opt, error_string, string);
+		}
+		style->c = 'p';
+	}
+	else
+		errx(1, "%s: Invalid style: %s", opt, string);
+}
+
+int main(int argc, char* argv[])
+{
+	const char* parameter;
+
+	for ( int i = 1; i < argc; i++ )
+	{
+		const char* arg = argv[i];
+		if ( arg[0] != '-' || !arg[1] )
+			continue;
+		argv[i] = NULL;
+		if ( !strcmp(arg, "--") )
+			break;
+		if ( arg[1] != '-' )
+		{
+			char c;
+			while ( (c = *++arg) ) switch ( c )
+			{
+			case 'b':
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'b'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				set_style(&styles[1], parameter, "-b");
+				arg = "b";
+				break;
+			case 'd':
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'd'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				if ( !parameter[0] )
+					memset(delim, 0, sizeof(delim));
+				else if ( !parameter[1] )
+				{
+					delim[0] = parameter[0];
+					delim[1] = ':';
+					delim[2] = parameter[0];
+					delim[3] = ':';
+					delim[4] = parameter[0];
+					delim[5] = ':';
+				}
+				else if ( !parameter[2] )
+				{
+					delim[0] = parameter[0];
+					delim[1] = parameter[1];
+					delim[2] = parameter[0];
+					delim[3] = parameter[1];
+					delim[4] = parameter[0];
+					delim[5] = parameter[1];
+				}
+				else
+					errx(1, "-d: Delimiter must be one or two characters");
+				arg = "d";
+				break;
+			case 'f':
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'f'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				set_style(&styles[2], parameter, "-f");
+				arg = "f";
+				break;
+			case 'h':
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'h'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				set_style(&styles[0], parameter, "-h");
+				arg = "h";
+				break;
+			case 'i':
+			{
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'i'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				char* end;
+				errno = 0;
+				intmax_t value = strtoimax(parameter, &end, 10);
+				if ( value < 0 || (off_t) value != value || *end )
+					errno = ERANGE;
+				if ( errno )
+					err(1, "-i: %s", parameter);
+				increment = (off_t) value;
+				arg = "i";
+				break;
+			}
+			case 'l':
+			{
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'l'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				char* end;
+				errno = 0;
+				intmax_t value = strtoimax(parameter, &end, 10);
+				if ( value < 0 || (off_t) value != value || *end )
+					errno = ERANGE;
+				if ( errno )
+					err(1, "-l: %s", parameter);
+				blank_join = (off_t) value;
+				arg = "l";
+				break;
+			}
+			case 'n':
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'n'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				if ( !strcmp(parameter, "ln") )
+					format = LN;
+				else if ( !strcmp(parameter, "rn") )
+					format = RN;
+				else if ( !strcmp(parameter, "rz") )
+					format = RZ;
+				else
+					errx(1, "-n: Invalid format: %s", parameter);
+				arg = "n";
+				break;
+			case 'p': restart = false; break;
+			case 's':
+				if ( !*(separator = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 's'");
+					separator = argv[i+1];
+					argv[++i] = NULL;
+				}
+				arg = "s";
+				break;
+			case 'v':
+			{
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'v'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				char* end;
+				errno = 0;
+				intmax_t value = strtoimax(parameter, &end, 10);
+				if ( value < 0 || (off_t) value != value || *end )
+					errno = ERANGE;
+				if ( errno )
+					err(1, "-v: %s", parameter);
+				initial = (off_t) value;
+				arg = "v";
+				break;
+			}
+			case 'w':
+			{
+				if ( !*(parameter = arg + 1) )
+				{
+					if ( i + 1 == argc )
+						errx(2, "option requires an argument -- 'w'");
+					parameter = argv[i+1];
+					argv[++i] = NULL;
+				}
+				char* end;
+				errno = 0;
+				long value = strtol(parameter, &end, 10);
+				if ( value < 0 || (int) value != value || *end )
+					errno = ERANGE;
+				if ( errno )
+					err(1, "-w: %s", parameter);
+				width = (int) value;
+				arg = "w";
+				break;
+			}
+			default:
+				errx(2, "unknown option -- '%c'", c);
+			}
+		}
+		else
+			errx(2, "unknown option: %s", arg);
+	}
+
+	compact_arguments(&argc, &argv);
+
+	line_number = initial;
+
+	int ret = 0;
+
+	if ( argc == 1 )
+	{
+		if ( !nl(stdin, "-") )
+			ret = 1;
+	}
+	else
+	{
+		for ( int i = 1; i < argc; i++ )
+		{
+			if ( !nl_path(argv[i]) )
+				ret = 1;
+		}
+	}
+
+	if ( ferror(stdout) || fflush(stdout) == EOF )
+		return 1;
+	return ret;
+}