3.t

早期freebsd实现

/var/spool/uucp	(uucp spooling area)
/var/tmp	(disk-based temporary directory)
/var/users	(root of per-machine user home directories)
.TE
.PP
The \*(4B bootstrap routines pass the identity of the boot device
through to the kernel.
The kernel then uses that device as its root filesystem.
Thus, for example, if you boot from
.Pn /dev/\*(Dk1a ,
the kernel will use
.Pn \*(Dk1a
as its root filesystem. If
.Pn /dev/\*(Dk1b
is configured as a swap partition, 
it will be used as the initial swap area,
otherwise the normal primary swap area (\c
.Pn /dev/\*(Dk0b )
will be used.
The \*(4B bootstrap is backward compatible with \*(Ps,
so you can replace your old bootstrap if you use it
to boot your first \*(4B kernel.
However, the \*(Ps bootstrap cannot access \*(4B filesystems,
so if you plan to convert your filesystems to \*(4B,
you must install a new bootstrap \fIbefore\fP doing the conversion.
Note that SPARC users cannot build a \*(4B compatible version
of the bootstrap, so must \fInot\fP convert their root filesystem
to the new \*(4B format.
.PP
Once you have extracted the \*(4B system and booted from it,
you will have to build a kernel customized for your configuration.
If you have any local device drivers,
they will have to be incorporated into the new kernel.
See section 4.1.3 and ``Building 4.3BSD UNIX Systems with Config'' (SMM:2).
.PP
If converting from \*(Ps, your old filesystems should be converted.
If you've modified the partition
sizes from the original \*(Ps ones, and are not already using the
\*(4B disk labels, you will have to modify the default disk partition
tables in the kernel.  Make the necessary table changes and boot
your custom kernel \fBBEFORE\fP trying to access any of your old
filesystems!  After doing this, if necessary, the remaining filesystems
may be converted in place by running the \*(4B version of
.Xr fsck (8)
on each filesystem and allowing it to make the necessary corrections.
The new version of
.Xr fsck
is more strict about the size of directories than
the version supplied with \*(Ps.
Thus the first time that it is run on a \*(Ps filesystem,
it will produce messages of the form:
.DS
\fBDIRECTORY ...: LENGTH\fP xx \fBNOT MULTIPLE OF 512 (ADJUSTED)\fP
.DE
Length ``xx'' will be the size of the directory;
it will be expanded to the next multiple of 512 bytes.
The new
.Xr fsck
will also set default \fIinterleave\fP and
\fInpsect\fP (number of physical sectors per track) values on older
filesystems, in which these fields were unused spares; this correction
will produce messages of the form:
.DS
\fBIMPOSSIBLE INTERLEAVE=0 IN SUPERBLOCK (SET TO DEFAULT)\fP\**
\fBIMPOSSIBLE NPSECT=0 IN SUPERBLOCK (SET TO DEFAULT)\fP
.DE
.FS
The defaults are to set \fIinterleave\fP to 1 and
\fInpsect\fP to \fInsect\fP.
This is correct on most drives;
it affects only performance (usually virtually unmeasurably).
.FE
Filesystems that have had their interleave and npsect values
set will be diagnosed by the old
.Xr fsck
as having a bad superblock; the old
.Xr fsck
will run only if given an alternate superblock
(\fIfsck \-b32\fP),
in which case it will re-zero these fields.
The \*(4B kernel will internally set these fields to their defaults
if fsck has not done so; again, the \fI\-b32\fP option may be
necessary for running the old
.Xr fsck .
.PP
In addition, \*(4B removes several limits on filesystem sizes
that were present in \*(Ps.
The limited filesystems
continue to work in \*(4B, but should be converted
as soon as it is convenient
by running
.Xr fsck
with the \fI\-c 2\fP option.
The sequence \fIfsck \-p \-c 2\fP will update them all,
fix the interleave and npsect fields,
fix any incorrect directory lengths,
expand maximum uid's and gid's to 32-bits,
place symbolic links less than 60 bytes into their inode,
and fill in directory type fields all at once.
The new filesystem formats are incompatible with older systems.
If you wish to continue using these filesystems with the older
systems you should make only the compatible changes using
\fIfsck \-c 1\fP.
.Sh 2 "Merging your files from \*(Ps into \*(4B"
.PP
When your system is booting reliably and you have the \*(4B root and
.Pn /usr
filesystems fully installed you will be ready
to continue with the next step in the conversion process,
merging your old files into the new system.
.PP
If you saved the files on a
.Xr tar
tape, extract them into a scratch directory, say
.Pn /usr/convert :
.DS
\fB#\fP \fImkdir /usr/convert\fP
\fB#\fP \fIcd /usr/convert\fP
\fB#\fP \fItar xp\fP
.DE
.PP
The data files marked in the previous table with a dagger (\(dg)
may be used without change from the previous system.
Those data files marked with a double dagger (\(dd) have syntax 
changes or substantial enhancements.
You should start with the \*(4B version and carefully
integrate any local changes into the new file.
Usually these local changes can be incorporated
without conflict into the new file;
some exceptions are noted below.
The files marked with an asterisk (*) require
particular attention and are discussed below.
.PP
As described in section 3.3,
the most immediately obvious change in \*(4B is the reorganization
of the system filesystems.
Users of certain recent vendor releases have seen this general organization,
although \*(4B takes the reorganization a bit further.
The directories most affected are
.Pn /etc ,
that now contains only system configuration files;
.Pn /var ,
a new filesystem containing per-system spool and log files; and
.Pn /usr/share,
that contains most of the text files shareable across architectures
such as documentation and macros.
System administration programs formerly in
.Pn /etc
are now found in
.Pn /sbin
and
.Pn /usr/sbin .
Various programs and data files formerly in
.Pn /usr/lib
are now found in
.Pn /usr/libexec
and
.Pn /usr/libdata ,
respectively.
Administrative files formerly in
.Pn /usr/adm
are in
.Pn /var/account
and, similarly, log files are now in
.Pn /var/log .
The directory
.Pn /usr/ucb
has been merged into
.Pn /usr/bin ,
and the sources for programs in
.Pn /usr/bin
are in
.Pn /usr/src/usr.bin .
Other source directories parallel the destination directories;
.Pn /usr/src/etc
has been greatly expanded, and
.Pn /usr/src/share
is new.
The source for the manual pages, in general, are with the source
code for the applications they document.
Manual pages not closely corresponding to an application program
are found in
.Pn /usr/src/share/man .
The locations of all man pages is listed in
.Pn /usr/src/share/man/man0/man[1-8] .
The manual page
.Xr hier (7)
has been updated and made more detailed;
it is included in the printed documentation.
You should review it to familiarize yourself with the new layout.
.PP
A new utility,
.Xr mtree (8),
is provided to build and check filesystem hierarchies
with the proper contents, owners and permissions.
Scripts are provided in
.Pn /etc/mtree
(and
.Pn /usr/src/etc/mtree )
for the root,
.Pn /usr
and
.Pn /var
filesystems.
Once a filesystem has been made for
.Pn /var ,
.Xr mtree
can be used to create a directory hierarchy there
or you can simply use tar to extract the prototype from
the second file of the distribution tape.
.Sh 3 "Changes in the \f(CW/etc\fP directory"
.PP
The
.Pn /etc
directory now contains nearly all the host-specific configuration
files.
Note that some file formats have changed,
and those configuration files containing pathnames are nearly all affected
by the reorganization.
See the examples provided in
.Pn /etc
(installed from
.Pn /usr/src/etc )
as a guide.
The following table lists some of the local configuration files
whose locations and/or contents have changed.
.TS
l l l
lfC lfC l.
\*(Ps and Earlier	\*(4B	Comments
_	_	_
/etc/fstab	/etc/fstab	new format; see below
/etc/inetd.conf	/etc/inetd.conf	pathnames of executables changed
/etc/printcap	/etc/printcap	pathnames changed
/etc/syslog.conf	/etc/syslog.conf	pathnames of log files changed
/etc/ttys	/etc/ttys	pathnames of executables changed
/etc/passwd	/etc/master.passwd	new format; see below
/usr/lib/sendmail.cf	/etc/sendmail.cf	changed pathnames
/usr/lib/aliases	/etc/aliases	may contain changed pathnames
/etc/*.pid	/var/run/*.pid	
	
.T&
l l l
lfC lfC l.
New in \*(Ps-Tahoe	\*(4B	Comments
_	_	_
/usr/games/dm.config	/etc/dm.conf	configuration for games (see \fIdm\fP\|(8))
/etc/zoneinfo/localtime	/etc/localtime	timezone configuration
/etc/zoneinfo	/usr/share/zoneinfo	timezone configuration
.TE
.ne 1.5i
.TS
l l l
lfC lfC l.
	New in \*(4B	Comments
_	_	_
	/etc/aliases.db	database version of the aliases file
	/etc/amd-home	location database of home directories
	/etc/amd-vol	location database of exported filesystems
	/etc/changelist	\f(CW/etc/security\fP files to back up
	/etc/csh.cshrc	system-wide csh(1) initialization file
	/etc/csh.login	system-wide csh(1) login file
	/etc/csh.logout	system-wide csh(1) logout file
	/etc/disklabels	directory for saving disklabels
	/etc/exports	NFS list of export permissions
	/etc/ftpwelcome	message displayed for ftp users; see ftpd(8)
	/etc/kerberosIV	Kerberos directory; see below
	/etc/man.conf	lists directories searched by \fIman\fP\|(1)
	/etc/mtree	directory for local mtree files; see mtree(8)
	/etc/netgroup	NFS group list used in \f(CW/etc/exports\fP
	/etc/pwd.db	non-secure hashed user data base file
	/etc/spwd.db	secure hashed user data base file
	/etc/security	daily system security checker
.TE
.PP
System security changes require adding several new ``well-known'' groups to
.Pn /etc/group .
The groups that are needed by the system as distributed are:
.TS
l n l.
name	number	purpose
_
wheel	0	users allowed superuser privilege
daemon	1	processes that need less than wheel privilege
kmem	2	read access to kernel memory
sys	3	access to kernel sources
tty	4	access to terminals
operator	5	read access to raw disks
bin	7	group for system binaries
news	8	group for news
wsrc	9	write access to sources
games	13	access to games
staff	20	system staff
guest	31	system guests
nobody	39	the least privileged group
utmp	45	access to utmp files
dialer	117	access to remote ports and dialers
.TE
Only users in the ``wheel'' group are permitted to
.Xr su
to ``root''.
Most programs that manage directories in
.Pn /var/spool
now run set-group-id to ``daemon'' so that users cannot
directly access the files in the spool directories.
The special files that access kernel memory,
.Pn /dev/kmem
and
.Pn /dev/mem ,
are made readable only by group ``kmem''.
Standard system programs that require this access are
made set-group-id to that group.
The group ``sys'' is intended to control access to kernel sources,
and other sources belong to group ``wsrc.''
Rather than make user terminals writable by all users,
they are now placed in group ``tty'' and made only group writable.
Programs that should legitimately have access to write on user terminals
such as
.Xr talkd
and
.Xr write
now run set-group-id to ``tty''.
The ``operator'' group controls access to disks.
By default, disks are readable by group ``operator'',
so that programs such as
.Xr dump
can access the filesystem information without being set-user-id to ``root''.
The
.Xr shutdown (8)
program is executable only by group operator
and is setuid to root so that members of group operator may shut down
the system without root access.
.PP
The ownership and modes of some directories have changed.
The
.Xr at
programs now run set-user-id ``root'' instead of ``daemon.''
Also, the uucp directory no longer needs to be publicly writable,
as
.Xr tip
reverts to privileged status to remove its lock files.
After copying your version of
.Pn /var/spool ,
you should do:
.DS
\fB#\fP \fIchown \-R root /var/spool/at\fP
\fB#\fP \fIchown \-R uucp.daemon /var/spool/uucp\fP
\fB#\fP \fIchmod \-R o\-w /var/spool/uucp\fP
.DE
.PP
The format of the cron table,
.Pn /etc/crontab ,
has been changed to specify the user-id that should be used to run a process.
The userid ``nobody'' is frequently useful for non-privileged programs.
Local changes are now put in a separate file,
.Pn /etc/crontab.local .
.PP
Some of the commands previously in
.Pn /etc/rc.local
have been moved to
.Pn /etc/rc ;
several new functions are now handled by
.Pn /etc/rc ,
.Pn /etc/netstart
and
.Pn /etc/rc.local .
You should look closely at the prototype version of these files