3.t

早期freebsd实现

.PP
Both the HP300 and SPARC ports feature the ability to run binaries
built for the native operating system (HP-UX or SunOS) by emulating
their system calls.
Building an HP300 kernel with the HPUXCOMPAT and COMPAT_OHPUX options
or a SPARC kernel with the COMPAT_SUNOS option will enable this feature
(on by default in the generic kernel provided in the root filesystem image).
Though this native operating system compatibility was provided by the
developers as needed for their purposes and is by no means complete,
it is complete enough to run several non-trivial applications including
those that require HP-UX or SunOS shared libraries.
For example, the vendor supplied X11 server and windowing environment
can be used on both the HP300 and SPARC.
.PP
It is important to remember that merely copying over a native binary
and executing it (or executing it directly across NFS) does not imply
that it will run.
All but the most trivial of applications are likely to require access
to auxiliary files that do not exist under \*(4B (e.g.
.Pn /etc/ld.so.cache )
or have a slightly different format (e.g.
.Pn /etc/passwd ).
However, by using system call tracing and
through creative use of symlinks,
many problems can be tracked down and corrected.
.PP
The DECstation port also has code for ULTRIX emulation
(kernel option ULTRIXCOMPAT, not compiled into the generic kernel)
but it was used primarily for initially bootstrapping the port and
has not been used since.
Hence, some work may be required to make it generally useful.
.Sh 3 "Changes to the utilities"
.PP
We have been tracking the IEEE Std1003.2 shell and utility work
and have included prototypes of many of the proposed utilities
based on draft 12 of the POSIX.2 Shell and Utilities document.
Because most of the traditional utilities have been replaced
with implementations conformant to the POSIX standards,
you should realize that the utility software may not be as stable,
reliable or well documented as in traditional Berkeley releases.
In particular, almost the entire manual suite has been rewritten to
reflect the POSIX defined interfaces, and in some instances
it does not correctly reflect the current state of the software.
It is also worth noting that, in rewriting this software, we have generally
been rewarded with significant performance improvements.
Most of the libraries and header files have been converted
to be compliant with ANSI C.
The shipped compiler (gcc) is a superset of ANSI C,
but supports traditional C as a command-line option.
The system libraries and utilities all compile
with either ANSI or traditional C.
.Sh 4 "Make and Makefiles"
.PP
This release uses a completely new version of the
.Xr make
program derived from the
.Xr pmake
program developed by the Sprite project at Berkeley.
It supports existing makefiles, although certain incorrect makefiles
may fail.
The makefiles for the \*(4B sources make extensive use of the new
facilities, especially conditionals and file inclusion, and are thus
completely incompatible with older versions of
.Xr make
(but nearly all the makefiles are now trivial!).
The standard include files for
.Xr make
are in
.Pn /usr/share/mk .
There is a
.Pn bsd.README
file in
.Pn /usr/src/share/mk .
.PP
Another global change supported by the new
.Xr make
is designed to allow multiple architectures to share a copy of the sources.
If a subdirectory named
.Pn obj
is present in the current directory,
.Xr make
descends into that directory and creates all object and other files there.
We use this by building a directory hierarchy in
.Pn /var/obj
that parallels
.Pn /usr/src .
We then create the
.Pn obj
subdirectories in
.Pn /usr/src
as symbolic links to the corresponding directories in
.Pn /var/obj .
(This step is automated.
The command ``make obj'' in
.Pn /usr/src
builds both the local symlink and the shadow directory,
using
.Pn /usr/obj ,
that may be a symbolic link, as the root of the shadow tree.
The use of
.Pn /usr/obj
is for historic reasons only, and the system make configuration files in
.Pn /usr/share/mk
can trivially be modified to use
.Pn /var/obj
instead.)
We have one
.Pn /var/obj
hierarchy on the local system, and another on each
system that shares the source filesystem.
All the sources in
.Pn /usr/src
except for
.Pn /usr/src/contrib
and portions of
.Pn /usr/src/old
have been converted to use the new make and
.Pn obj
subdirectories;
this change allows compilation for multiple
architectures from the same source tree
(that may be mounted read-only).
.Sh 4 "Kerberos"
.PP
The Kerberos authentication server from MIT (version 4)
is included in this release.
See
.Xr kerberos (1)
for a general, if MIT-specific, introduction.
If it is configured,
.Xr login (1),
.Xr passwd (1),
.Xr rlogin (1)
and
.Xr rsh (1)
will all begin to use it automatically.
The file
.Pn /etc/kerberosIV/README
describes the configuration.
Each system needs the file
.Pn /etc/kerberosIV/krb.conf
to set its realm and local servers,
and a private key stored in
.Pn /etc/kerberosIV/srvtab
(see
.Xr ext_srvtab (8)).
The Kerberos server should be set up on a single, physically secure,
server machine.
Users and hosts may be added to the server database manually with
.Xr kdb_edit (8),
or users on authorized hosts can add themselves and a Kerberos
password after verification of their ``local'' (passwd-file) password
using the
.Xr register (1)
program.
.PP
Note that by default the password-changing program
.Xr passwd (1)
changes the Kerberos password, that must exist.
The
.Li \-l
option to
.Xr passwd (1)
changes the ``local'' password if one exists.
.PP
Note that Version 5 of Kerberos will be released soon;
Version 4 should probably be replaced at that time.
.Sh 4 "Timezone support"
.PP
The timezone conversion code in the C library uses data files installed in
.Pn /usr/share/zoneinfo
to convert from ``GMT'' to various timezones.  The data file for the default
timezone for the system should be copied to
.Pn /etc/localtime .
Other timezones can be selected by setting the TZ environment variable.
.PP
The data files initially installed in
.Pn /usr/share/zoneinfo
include corrections for leap seconds since the beginning of 1970.
Thus, they assume that the
kernel will increment the time at a constant rate during a leap second;
that is, time just keeps on ticking.  The conversion routines will then
name a leap second 23:59:60.  For purists, this effectively means that
the kernel maintains TAI (International Atomic Time) rather than UTC
(Coordinated Universal Time, aka GMT).
.PP
For systems that run current NTP (Network Time Protocol) implementations
or that wish to conform to the letter of the POSIX.1 law, it is possible
to rebuild the timezone data files so that leap seconds are not counted.
(NTP causes the time to jump over a leap second, and POSIX effectively
requires the clock to be reset by hand when a leap second occurs.
In this mode, the kernel effectively runs UTC rather than TAI.)
.PP
The data files without leap second information
are constructed from the source directory,
.Pn /usr/src/share/zoneinfo .
Change the variable REDO in Makefile
from ``right'' to ``posix'', and then do
.DS
make obj	(if necessary)
make
make install
.DE
.PP
You will then need to copy the correct default zone file to
.Pn /etc/localtime ,
as the old one would still have used leap seconds, and because the Makefile
installs a default
.Pn /etc/localtime
each time ``make install'' is done.
.PP
It is possible to install both sets of timezone data files.  This results
in subdirectories
.Pn /usr/share/zoneinfo/right
and
.Pn /usr/share/zoneinfo/posix .
Each contain a complete set of zone files.
See
.Pn /usr/src/share/zoneinfo/Makefile
for details.
.Sh 4 "Additions and changes to the libraries"
.PP
Notable additions to the libraries include functions to traverse a
filesystem hierarchy, database interfaces to btree and hashing functions,
a new, faster implementation of stdio and a radix and merge sort
functions.
.PP
The
.Xr fts (3)
functions will do either physical or logical traversal of
a file hierarchy as well as handle essentially infinite depth
filesystems and filesystems with cycles.
All the utilities in \*(4B which traverse file hierarchies
have been converted to use
.Xr fts (3).
The conversion has always resulted in a significant performance
gain, often of four or five to one in system time.
.PP
The
.Xr dbopen (3)
functions are intended to be a family of database access methods.
Currently, they consist of
.Xr hash (3),
an extensible, dynamic hashing scheme,
.Xr btree (3),
a sorted, balanced tree structure (B+tree's), and
.Xr recno (3),
a flat-file interface for fixed or variable length records
referenced by logical record number.
Each of the access methods stores associated key/data pairs and
uses the same record oriented interface for access.
.PP
The
.Xr qsort (3)
function has been rewritten for additional performance.
In addition, three new types of sorting functions,
.Xr heapsort (3),
.Xr mergesort (3)
and
.Xr radixsort (3)
have been added to the system.
The
.Xr mergesort
function is optimized for data with pre-existing order,
in which case it usually significantly outperforms
.Xr qsort .
The
.Xr radixsort (3)
functions are variants of most-significant-byte radix sorting.
They take time linear to the number of bytes to be
sorted, usually significantly outperforming
.Xr qsort
on data that can be sorted in this fashion.
An implementation of the POSIX 1003.2 standard
.Xr sort (1),
based on
.Xr radixsort ,
is included in
.Pn /usr/src/contrib/sort .
.PP
Some additional comments about the \*(4B C library:
.IP \(bu
The floating point support in the C library has been replaced
and is now accurate.
.IP \(bu
The C functions specified by both ANSI C, POSIX 1003.1 and
1003.2 are now part of the C library.
This includes support for file name matching, shell globbing
and both basic and extended regular expressions.
.IP \(bu
ANSI C multibyte and wide character support has been integrated.
The rune functionality from the Bell Labs' Plan 9 system is provided
as well.
.IP \(bu
The
.Xr termcap (3)
functions have been generalized and replaced with a general
purpose interface named
.Xr getcap (3).
.IP \(bu
The
.Xr stdio (3)
routines have been replaced, and are usually much faster.
In addition, the
.Xr funopen (3)
interface permits applications to provide their own I/O stream
function support.
.PP
The
.Xr curses (3)
library has been largely rewritten.
Important additional features include support for scrolling and
.Xr termios (3).
.PP
An application front-end editing library, named libedit, has been
added to the system.
.PP
A superset implementation of the SunOS kernel memory interface library,
libkvm, has been integrated into the system.
.PP
.Sh 4 "Additions and changes to other utilities"
.PP
There are many new utilities, offering many new capabilities,
in \*(4B.
Skimming through the section 1 and section 8 manual pages is sure
to be useful.
The additions to the utility suite include greatly enhanced versions of
programs that display system status information, implementations of
various traditional tools described in the IEEE Std1003.2 standard,
new tools not previous available on Berkeley UNIX systems,
and many others.
Also, with only a very few exceptions, all the utilities from
\*(Ps that included proprietary source code have been replaced,
and their \*(4B counterparts are freely redistributable.
Normally, this replacement resulted in significant performance
improvements and the increase of the limits imposed on data by
the utility as well.
.PP
A summary of specific additions and changes are as follows:
.TS
lfC l.
amd	An auto-mounter implementation.
ar	Replacement of the historic archive format with a new one.
awk	Replaced by gawk; see /usr/src/old/awk for the historic version.
bdes	Utility implementing DES modes of operation described in FIPS PUB 81.
calendar	Addition of an interface for system calendars.
cap_mkdb	Utility for building hashed versions of termcap style databases.
cc	Replacement of pcc with gcc suite.
chflags	A utility for setting the per-file user and system flags.
chfn	An editor based replacement for changing user information.
chpass	An editor based replacement for changing user information.
chsh	An editor based replacement for changing user information.
cksum	The POSIX 1003.2 checksum utility; compatible with sum.
column	A columnar text formatting utility.
cp	POSIX 1003.2 compatible, able to copy special files.
csh	Freely redistributable and 8-bit clean.
date	User specified formats added.
dd	New EBCDIC conversion tables, major performance improvements.
dev_mkdb	Hashed interface to devices.
dm	Dungeon master.
find	Several new options and primaries, major performance improvements.
fstat	Utility displaying information on files open on the system.
ftpd	Connection logging added.