All rights reserved. The Berkeley software License Agreement
specifies the terms and conditions for redistribution.
@(#)3.t 6.1 (Berkeley) 05/14/86
.nr H1 3 .nr H2 0 .bp
3. UPGRADING A 4.2BSD SYSTEM .R
Begin by reading the ``Bugs Fixes and Changes in \*(4B'' document to see what has changed since the last time you bootstrapped the system. If you have local system modifications to the kernel to install, look at the document ``Changes to the Kernel in \*(4B'' to get an idea of how the system changes will affect your local modifications.
If you are running 4.2BSD, upgrading your system involves replacing your kernel and system utilities. Binaries compiled under 4.2BSD will work without recompilation under \*(4B, though they may run faster if they are relinked. The easiest way to convert to \*(4B (depending on your file system configuration) is to create new root and /usr file systems from the distribution tape on unused disk partitions, boot the new system, and then copy any local utilities from your old root and /usr file systems into the new ones. All user file systems and binaries can be retained unmodified, except that the new fsck should be run before they are mounted (see below). 4.1BSD binary images can also run unchanged under \*(4B but only when the system is configured to include the ``4.1BSD compatibility mode.''* .FS * With ``4.1BSD compatibility mode'' system calls from 4.1BSD are either emulated or safely ignored. There are only two exceptions; programs that read directories or use the old jobs library will not operate properly. However, while 4.1BSD binaries will execute under \*(4B it is STRONGLY RECOMMENDED that the programs be recompiled under the new system. .FE
Section 3.1 lists the files to be saved as part of the conversion process. Section 3.2 describes the bootstrap process. Section 3.3 discusses the merger of the saved files back into the new system. Section 3.4 provides general hints on possible problems to be aware of when converting from 4.2BSD to \*(4B. Files to save
The easiest upgrade path from a 4.2BSD is to build new root and usr file systems on unused partitions, then copy or merge site specific files into their corresponding files on the new system. The following list enumerates the standard set of files you will want to save and suggests directories in which site specific files should be present. This list will likely be augmented with non-standard files you have added to your system. If you do not have enough space to create parallel file systems, you should create a tar image of the following files before the new file systems are created. In addition, you should do a full dump before rebuilding the file system to guard against missing something the first time around.
| /.cshrc \(dg root csh startup script |
| /.login \(dg root csh login script |
| /.profile \(dg root sh startup script |
| /.rhosts \(dg for trusted machines and users |
| /dev/MAKEDEV \(dd in case you added anything here |
| /dev/MAKEDEV.local * for making local devices |
| /etc/disktab \(dd in case you changed disk partition sizes |
| /etc/fstab \(dg disk configuration data |
| /etc/ftpusers \(dg for local additions |
| /etc/gateways \(dg routing daemon database |
| /etc/gettytab \(dd getty database |
| /etc/group * group data base |
| /etc/hosts \(dg for local host information |
| /etc/hosts.equiv \(dg for local host equivalence information |
| /etc/networks \(dg for local network information |
| /etc/passwd * user data base |
| /etc/printcap \(dg line printer database |
| /etc/protocols \(dd in case you added any local protocols |
| /etc/rc * for any local additions |
| /etc/rc.local * site specific system startup commands |
| /etc/remote \(dg auto-dialer configuration |
| /etc/services \(dd for local additions |
| /etc/syslog.conf * system logger configuration |
| /etc/securettys * for restricted list of ttys where root can log in |
| /etc/ttys * terminal line configuration data |
| /etc/ttytype * terminal line to terminal type mapping data |
| /etc/termcap \(dd for any local entries that may have been added |
| /lib \(dd for any locally developed language processors |
| /usr/dict/* \(dd for local additions to words and papers |
| /usr/hosts/MAKEHOSTS \(dg for local changes |
| /usr/include/* \(dd for local additions |
| /usr/lib/aliases \(dg mail forwarding data base |
| /usr/lib/crontab * cron daemon data base |
| /usr/lib/font/* \(dd for locally developed font libraries |
| /usr/lib/lib*.a \(dg for locally libraries |
| /usr/lib/lint/* \(dd for locally developed lint libraries |
| /usr/lib/sendmail.cf * sendmail configuration |
| /usr/lib/tabset/* \(dd for locally developed tab setting files |
| /usr/lib/term/* \(dd for locally developed nroff drive tables |
| /usr/lib/tmac/* \(dd for locally developed troff/nroff macros |
| /usr/lib/uucp/* \(dg for local uucp configuration files |
| /usr/man/manl \(dg for manual pages for locally developed programs |
| /usr/msgs \(dg for current msgs |
| /usr/spool/* \(dg for current mail, news, uucp files, etc. |
| /usr/src/local \(dg for source for locally developed programs |
| /sys/conf/HOST \(dg configuration file for your machine |
| /sys/conf/files.HOST \(dg list of special files in your kernel |
| /*/quotas \(dg file system quota files |
The next step is to build a working \*(4B system. This can be done by following the steps in section 2 of this document for extracting the root and /usr file systems from the distribution tape onto unused disk partitions. If you have a running 4.2BSD system, you can also do this by using dd (1) to copy the \*(lqmini root\*(rq filesystem onto one disk partition, then use it to load the \*(4B root filesystem as as chapter 2. The root filesystem dump on the tape could also be extracted directly, although this will require an additional file system check after booting \*(4B to convert the new root filesystem. The exact procedure chosen will depend on the disk configuration and the number of suitable disk partitions that may be used. If there is insufficient space to load the new root and /usr filesystems before reusing the existing 4.2BSD partitions, it is strongly advised that you make full dumps of each filesystem on magtape before beginning. It is also desirable to run file system checks of all filesystems to be converted to \*(4B before shutting down 4.2BSD. If you are running an older system, you will have to dump and restore your file systems; see section 2.1 for some hints. In either case, this is an excellent time to review your disk configuration for possible tuning of the layout. Section 4.3 is required reading.
To ease the transition to new kernels, the 4.3BSD bootstrap routines now pass the identity of the boot device through to the kernel. The kernel then uses that device as its root file system. Thus, for example, if you boot from /dev/hp1a, the kernel will use hp1a as its root file system. If /dev/hp1b is configured as a swap partition, it will be used as the initial swap area, otherwise the normal primary swap area (/dev/hp0b) will be used. The \*(4B bootstrap is backward compatible with 4.2BSD, so you can replace your 4.2BSD bootstrap if you use it to boot your first \*(4B kernel.
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 4.2.3 and ``Building 4.3BSD UNIX Systems with Config.''
The disk partitions in \*(4B are the same as those in 4.2BSD, except for those on the DEC UDA50; see section 4.3.2 for details. If you have changed the disk partition sizes, be sure to make the necessary table changes and boot your custom kernel BEFORE trying to access any of your 4.2BSD file systems! After doing this if necessary, the remaining 4.2BSD filesystems may be converted in place. This is done by using the \*(4B version of fsck (8) on each filesystem and allowing it to make the necessary corrections. The new version of fsck is more strict about the size of directories than the version supplied with 4.2BSD. Thus the first time that it is run on a 4.2BSD file system, it will produce messages of the form: DIRECTORY ...: LENGTH xx NOT MULTIPLE OF 512 (ADJUSTED) Length ``xx'' will be the size of the directory; it will be expanded to the next multiple of 512 bytes. Note that file systems are otherwise completely compatible between 4.2BSD and \*(4B, though running a \*(4B file system under 4.2BSD may cause more of the above messages to be generated the next time it is fsck'ed on \*(4B. Merging your files from 4.2BSD into \*(4B
When your system is booting reliably and you have the \*(4B root and /usr file systems fully installed you will be ready to continue with the next step in the conversion process, merging your old files into the new system.
If you saved the files on a tar tape, extract them into a scratch directory, say /usr/convert: # mkdir /usr/convert # cd /usr/convert # tar x
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 modifications 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.
If you have any homegrown device drivers in /dev/MAKEDEV.local that use major device numbers reserved by the system you will have to modify the commands used to create the devices or alter the system device configuration tables in /sys/vax/conf.c. Otherwise /dev/MAKEDEV.local can be used without change from 4.2BSD.
System security changes require adding several new ``well-known'' groups to /etc/group. The groups that are needed by the system as distributed are:
| name number |
| wheel 0 |
| daemon 1 |
| kmem 2 |
| sys 3 |
| tty 4 |
| operator 5 |
| staff 10 |
Several new users have also been added to the group of ``well-known'' users in /etc/passwd. The current list is:
| name number |
| root 0 |
| daemon 1 |
| operator 2 |
| uucp 66 |
| nobody 32767 |
After installing your updated password file, you must run mkpasswd\|(8) to create the ndbm password database. Note that mkpasswd is run whenever vipw\|(8) is run.
The format of the cron table, /usr/lib/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.
Some of the commands previously in /etc/rc.local have been moved to /etc/rc; several new functions are now handled by /etc/rc.local. You should look closely at the prototype version of /etc/rc.local and read the manual pages for the commands contained in it before trying to merge your local copy. Note in particular that ifconfig has had many changes, and that host names are now fully specified as domain-style names (e.g, monet.Berkeley.EDU) for the benefit of the name server.
The C library and system binaries on the distribution tape are compiled with new versions of gethostbyname and gethostbyaddr which use the name server, named (8). If you have only a small network and are not connected to a large network, you can use the distributed library routines without any problems; they use a linear scan of the host table /etc/hosts if the name server is not running. If you are on the DARPA Internet or have a large local network, it is recommend that you set up and use the name server. For instructions on how to set up the necessary configuration files, refer to ``Name Server Operations Guide for BIND''. Several programs rely on the host name returned by gethostname to determine the local domain name.
If you want to compile your system to use the host table lookup routines instead of the name server, you will need to modify /usr/src/lib/libc/Makefile according to the instructions there and then recompile all of the system and local programs (see section 6.6). Next, you must run mkhosts\|(8) to create the ndbm host table database from /etc/hosts.
The format of /etc/ttys has changed, see ttys\|(5) for details. It now includes the terminal type and security options that were previously placed in /etc/ttytype and /etc/securettys.
There is a new version of syslog that uses a more generalized facility/priority scheme. This has changed the format of the syslog.conf file. See syslogd\|(8) for details. Syslog now logs kernel errors, allowing events such as soft disk errors, filesystem-full messages, and other such error messages to be logged without slowing down the system while the messages print on the console. It is also used by many of the system daemons to monitor system problems more closely, for example network routing changes.
If you are using the name server, your sendmail configuration file will need some minor updates to accommodate it. See the ``Sendmail Installation and Operation Guide'' and the sample sendmail configuration files in /usr/src/usr.lib/sendmail/nscf. Be sure to regenerate your sendmail frozen configuration file after installation of your updated configuration file.
The spooling directories saved on tape may be restored in their eventual resting places without too much concern. Be sure to use the `p' option to tar so that files are recreated with the same file modes: # cd /usr # tar xp msgs spool/mail spool/uucp spool/uucppublic spool/news
The ownership and modes of two of these directories at now runs set-user-id ``daemon'' instead of root. Also, the uucp directory no longer needs to be publicly writable, as tip reverts to priveleged status to remove its lock files. After copying your version of /usr/spool, you should do: # chown -R daemon /usr/spool/at # chown -R root /usr/spool/uucp # chgrp -R daemon /usr/spool/uucp # chmod -R o-w /usr/spool/uucp
Whatever else is left is likely to be site specific or require careful scrutiny before placing in its eventual resting place. Refer to the documentation and source code before arbitrarily overwriting a file. Hints on converting from 4.2BSD to \*(4B
This section summarizes the most significant changes between 4.2BSD and \*(4B, particularly those that are likely to cause difficulty in doing the conversion. It does not include changes in the network; see chapter 5 for information on setting up the network.
The mailbox locking protocol has changed; it now uses the advisory locking facility to avoid concurrent update of users' mail boxes. If you have your own mail interface, be sure to update its locking protocol.
The kernel's limit on the number of open files has been increased from 20 to 64. It is now possible to change this limit almost arbitrarily (there used to be a hard limit of 30). The standard I/O library autoconfigures to the kernel limit. Note that file (``_iob'') entries may be allocated by malloc from fopen; this allocation has been known to cause problems with programs that use their own memory allocators. This does not occur until after 20 files have been opened by the standard I/O library.
Select can be used with more than 32 descriptors by using arrays of ints for the bit fields rather than single ints. Programs that used getdtablesize as their first argument to select will no longer work correctly. Usually the program can be modified to correctly specify the number of bits in an int. Alternatively the program can be modified to use an array of ints. There are a set of macros available in <sys/types.h> to simplify this. See select (2).
Old core files will not be intelligible by the current debuggers because of numerous changes to the user structure and because the kernel stack has been enlarged. The a.out header that was in the user structure is no longer present. Locally-written debuggers that try to check the magic number will need modification.
Find now has a database of file names, constructed once a week from cron. To find a file by name only, the command find name will look in the database for files that match the name. This is much faster than find / -name name -print.
Files may not be deleted from directories having the ``sticky'' (ISVTX) bit set in their modes except by the owner of the file or of the directory, or by the superuser. This is primarily to protect users' files in publicly-writable directories such as /tmp and /usr/tmp. All publicly-writable directories should have their ``sticky'' bits set with ``chmod +t.''
The include file <time.h> has returned to /usr/include, and again contains the definitions for the C library time routines of ctime\|(3).
The compact and uncompact programs have been supplanted by the faster compress. If your user population has compacted files, you will want to install uncompact found in /usr/src/old/compact.
The configuration of the virtual memory limits has been simplified. A MAXDSIZ option, specified in bytes in the machine configuration file, may be used to raise the maximum process region size from the default of 17Mb to 32Mb or 64Mb. The initial per-process limit is still 6Mb, but can be raised up to MAXDSIZ with the csh limit command.
Some \*(4B binaries will not run with a 4.2BSD kernel because they take advantage of new functionality in \*(4B. One noticeable example of this problem is csh.
If you want to use ps after booting a new kernel, and before going multiuser, you must initialize its name list database by running ps -U.