diff --git a/libc/include/sysexits.h b/libc/include/sysexits.h
index 97f5366..b0001e6 100644
--- a/libc/include/sysexits.h
+++ b/libc/include/sysexits.h
@@ -32,90 +32,134 @@
  *	@(#)sysexits.h	4.8 (Berkeley) 4/3/91
  */
 
-#ifndef	_SYSEXITS_H_
-#define	_SYSEXITS_H_
+#pragma once
+
+/**
+ * @file sysexits.h
+ * @brief Exit status codes for system programs.
+ *
+ * This include file attempts to categorize possible error
+ * exit statuses for system programs such as sendmail.
+ */
 
 #include <sys/cdefs.h>
 
-/*
- *  SYSEXITS.H -- Exit status codes for system programs.
- *
- *	This include file attempts to categorize possible error
- *	exit statuses for system programs, notably delivermail
- *	and the Berkeley network.
- *
- *	Error numbers begin at EX__BASE to reduce the possibility of
- *	clashing with other exit statuses that random programs may
- *	already return.  The meaning of the codes is approximately
- *	as follows:
- *
- *	EX_USAGE -- The command was used incorrectly, e.g., with
- *		the wrong number of arguments, a bad flag, a bad
- *		syntax in a parameter, or whatever.
- *	EX_DATAERR -- The input data was incorrect in some way.
- *		This should only be used for user's data & not
- *		system files.
- *	EX_NOINPUT -- An input file (not a system file) did not
- *		exist or was not readable.  This could also include
- *		errors like "No message" to a mailer (if it cared
- *		to catch it).
- *	EX_NOUSER -- The user specified did not exist.  This might
- *		be used for mail addresses or remote logins.
- *	EX_NOHOST -- The host specified did not exist.  This is used
- *		in mail addresses or network requests.
- *	EX_UNAVAILABLE -- A service is unavailable.  This can occur
- *		if a support program or file does not exist.  This
- *		can also be used as a catchall message when something
- *		you wanted to do doesn't work, but you don't know
- *		why.
- *	EX_SOFTWARE -- An internal software error has been detected.
- *		This should be limited to non-operating system related
- *		errors as possible.
- *	EX_OSERR -- An operating system error has been detected.
- *		This is intended to be used for such things as "cannot
- *		fork", "cannot create pipe", or the like.  It includes
- *		things like getuid returning a user that does not
- *		exist in the passwd file.
- *	EX_OSFILE -- Some system file (e.g., /etc/passwd, /var/run/utmp,
- *		etc.) does not exist, cannot be opened, or has some
- *		sort of error (e.g., syntax error).
- *	EX_CANTCREAT -- A (user specified) output file cannot be
- *		created.
- *	EX_IOERR -- An error occurred while doing I/O on some file.
- *	EX_TEMPFAIL -- temporary failure, indicating something that
- *		is not really an error.  In sendmail, this means
- *		that a mailer (e.g.) could not create a connection,
- *		and the request should be reattempted later.
- *	EX_PROTOCOL -- the remote system returned something that
- *		was "not possible" during a protocol exchange.
- *	EX_NOPERM -- You did not have sufficient permission to
- *		perform the operation.  This is not intended for
- *		file system problems, which should use EX_NOINPUT or
- *		EX_CANTCREAT, but rather for higher level permissions.
- *	EX_CONFIG -- Something was found in an unconfigured or
- *		misconfigured state.
+/** Successful termination. */
+#define EX_OK  0
+
+/**
+ * Base value for error messages.
+ * Error numbers begin at `EX__BASE` to reduce the possibility of
+ * clashing with other exit statuses that random programs may
+ * already return.
  */
+#define EX__BASE 64
 
-#define EX_OK		0	/* successful termination */
+/**
+ * Command line usage error.
+ * The command was used incorrectly, such as the wrong number of
+ * arguments, a bad flag, or bad syntax for a parameter.
+ */
+#define EX_USAGE 64
 
-#define EX__BASE	64	/* base value for error messages */
+/**
+ * Data format error.
+ * The input data was incorrect in some way.
+ * This should only be used for user's data and not for system files.
+ */
+#define EX_DATAERR 65
 
-#define EX_USAGE	64	/* command line usage error */
-#define EX_DATAERR	65	/* data format error */
-#define EX_NOINPUT	66	/* cannot open input */
-#define EX_NOUSER	67	/* addressee unknown */
-#define EX_NOHOST	68	/* host name unknown */
-#define EX_UNAVAILABLE	69	/* service unavailable */
-#define EX_SOFTWARE	70	/* internal software error */
-#define EX_OSERR	71	/* system error (e.g., can't fork) */
-#define EX_OSFILE	72	/* critical OS file missing */
-#define EX_CANTCREAT	73	/* can't create (user) output file */
-#define EX_IOERR	74	/* input/output error */
-#define EX_TEMPFAIL	75	/* temp failure; user is invited to retry */
-#define EX_PROTOCOL	76	/* remote error in protocol */
-#define EX_NOPERM	77	/* permission denied */
-#define EX_CONFIG	78	/* configuration error */
+/**
+ * Cannot open input.
+ * An input file (not a system file) did not exist or was not readable.
+ * This could also include errors like "No message" to a mailer (if it cared
+ * to catch it).
+ */
+#define EX_NOINPUT 66
 
-#define EX__MAX		78	/* maximum listed value */
+/**
+ * The specified user did not exist.
+ * This might be used for mail addresses or remote logins.
+ */
+#define EX_NOUSER 67
 
-#endif /* !_SYSEXITS_H_ */
+/**
+ * The specified host did not exist.
+ * This is used in mail addresses or network requests.
+ */
+#define EX_NOHOST 68
+
+/**
+ * A service is unavailable.
+ * This can occur if a support program or file does not exist.
+ * This can also be used as a catchall message when something
+ * you wanted to do doesn't work, but you don't know why.
+ */
+#define EX_UNAVAILABLE 69
+
+/**
+ * An internal software error has been detected.
+ * This should be limited to non-operating system related errors.
+ */
+#define EX_SOFTWARE 70
+
+/**
+ * An operating system error has been detected.
+ * This is intended to be used for such things as "cannot
+ * fork", "cannot create pipe", or the like.  It includes
+ * things like getuid returning a user that does not
+ * exist in the passwd file.
+ */
+#define EX_OSERR 71
+
+/**
+ * Critical OS file error.
+ * A system file (such as /etc/passwd) does not exist, cannot be opened,
+ * or has some other problem (such as a syntax error).
+ */
+#define EX_OSFILE 72
+
+/**
+ * Can't create (user) output file.
+ * A (user specified) output file cannot be created.
+ */
+#define EX_CANTCREAT 73
+
+/**
+ * Input/output error.
+ * An error occurred while doing I/O on some file.
+ */
+#define EX_IOERR 74
+
+/**
+ * Temporary failure; user is invited to retry.
+ * A temporary failure, indicating something that
+ * is not really an error.  In sendmail, this might mean
+ * that a mailer could not create a connection,
+ * and the request should be reattempted later.
+ */
+#define EX_TEMPFAIL 75
+
+/**
+ * Remote error in protocol.
+ * The remote system returned something that
+ * was "not possible" during a protocol exchange.
+ */
+#define EX_PROTOCOL 76
+
+/**
+ * Permission denied.
+ * You did not have sufficient permission to perform the operation.
+ * This is not intended for file system problems, which should use EX_NOINPUT or
+ * EX_CANTCREAT, but rather for higher level permissions.
+ */
+#define EX_NOPERM 77
+
+/**
+ * Configuration error.
+ * Something was found in an unconfigured or misconfigured state.
+ */
+#define EX_CONFIG 78
+
+/** Maximum listed value. */
+#define EX__MAX  78