BSD 4_3 development

[unix-history] / usr / doc / misc / uchanges.4.1

.de IR
\fI\\$1\fR\\$2\\fR\\fR
..
.TL
Bug fixes and changes in 4.1bsd
.sp
May 10, 1981
.AU
Bill Joy
.AI
Computer Systems Research Group
.AB
This document describes briefly the changes in the Berkeley system
for the VAX between the fourth distribution of November 1980 (known originally
as 4BSD, and hereinafter referred to as 4.0bsd)
and this, its revision of April 1981.
It attempts to be summarize, without going into great detail, the
changes which have been made.
.AE
.SH
.ce
.LG
Notable improvements
.SM
.sp
.IP \s+1\(bu\s0
Performance of the system under heavy paging load has been substantially
improved by correcting a problem with placement of pre-paged pages.
The system now pre-pages more data, greatly benefitting processes which
have locality in their behavior.  System degradation due to pre-paging has
been reduced (even though more pre-paging is done), by placing the pre-paged
pages as the bottom of the free-list, rather than in the systems global
clock replacement loop.
.IP \s+1\(bu\s0
Processes which serially reference large amounts of virtual memory
may now declare themselves to be sequential (see
.IR vadvise (2)),
causing the paging algorithm to be adjusted to be more appropriate for
such behavior.*
.FS
* Future versions of the system will detect strongly sequential behavior
and adapt themselves accordingly, so this call will no longer be necessary.
.FE
Processes which are known to need only a small amount of memory, but
which tend to accumulate large amounts of memory due to strange page
referencing patterns may declare a soft limit on the amount of memory
to be used, see
.IR vlimit (2)
or do ``limit memoryuse \fIn\fR\|k'' in
.IR csh (1).
If the system needs memory, and there are processes which are over their
declared limits, the system tends to take pages from these processes first.
By saying that these limits are soft, we mean that on a system where
physical memory is not scarce, processes with limits can still acquire as much
physical memory as they require.
.IP \s+1\(bu\s0
The system is now compiled from a description of the local machine
which includes information about available devices and the maximum
number of users to be supported on the system.  It is no longer
necessary to adjust an armful of constants to re-size the system; normal
time-sharing systems are parameterized from a single ``maxusers'' constant.
The system also adjusts the parameters of the paging subsystem based
on available memory; it is no longer necessary to adjust these for machines
with very small or very large amounts of available memory.
.IP \s+1\(bu\s0
The system now handles multiple uba's and mba's and mixing of devices
on mba's.  A number of new devices are supported: RK07's and TS-11's
which come in the standard 11/750 packages, UNIBUS TM-11 tape emulators
(e.g. the EMULEX TC-11 with a KENNEDY 9300 transport).  Line printer
and C/A/T phototypesetter drivers are included in the system, and
modem control for the DH-11 using the DM-11 has been integrated and
tested.  The new RM-80 Winchester drive from DEC is supported.
Notably unsupported are the 11/750 console casettes.
A single distribution system boots on all supported hardware configurations
by determining the available devices and selecting a root device at boot
time.
.IP \s+1\(bu\s0
The \fItar\fR program has been changed to allow update of
magnetic tape archives, adding to the end of the existing tape
archive.  This uses tape control facilities newly added in this
version of the system, but the created tapes are readable on
all versions of UNIX.  Since blocked tapes are inherently more
efficient and fully functional, \fItar\fR now creates blocked tapes by default.
.IP \s+1\(bu\s0
Shell scripts are now potentially executable.  A file which begins
with the characters ``#!'' followed by some amount of white space
and the name of an interpreter is executed directly by the system.
The standard version 7 shell, /bin/sh, has been changed to recognize
a # as a comment character.  It is desirable that users change
existing shell script so that the first line of each shell script
begins with ``#!'' and the name of the proper shell to execute.
.IP \s+1\(bu\s0
Two new documents have been added to Volume 2c: a manual for the
crt screen package \fB\-lcurses\fR, and a document describing the
\fBrogue\fR game.
.br
.ne 10
.LP
.LP
.ce
.LG
.B "Major bug fixes"
.SM
.sp
.IP \s+1\(bu\s0
A number of bugs have been fixed in the FORTRAN compiler F77;
these caused some block data routiens and main programs to fail to compile.
Other bugs related to use of the symbolic debugger with FORTRAN
have been fixed (see \fBf77\fR in ``Section 1'' below.)
.IP \s+1\(bu\s0
A bug which caused the C compiler to complain ``expression too complicated''
when an expression contained an embedded structure assignment has been fixed.
.IP \s+1\(bu\s0
A kernel bug which caused approximately 1/8'th of data collected during
program profiling to be lost has been corrected.
.IP \s+1\(bu\s0
A very confusing bug in the \fItset\fR manual page has been corrected:
in the example where it uses the \fIsetenv\fR command it should rather
use the \fIset\fR command: ``set noglob; eval ...''.  The alternate
form does not work on a number of terminals.
.IP \s+1\(bu\s0 4
Due to a inconsistency between the 11/780 and the 11/750 in the
interpretation of the \fBmovtuc\fR instruction, all binaries from
the third distribution tape (of January 1980) and the fourth
distribution tape (of November 1980) will NOT run correctly on
the 11/750.  The 4.1bsd distribution tape includes a new
version of the standard i/o
library which avoids use of this troublesome instruction, and it
is recommended that all programs be recompiled from scratch to use
this new library to eliminate non-portable UNIX binaries as soon
as possible.
.IP
The problem is that when there appears to be a chance that the operands
to \fBmovtuc\fR will overlap, but they in fact do not (because the
pattern string to printf is terminated by a null), the 11/750 does
not execute the \fBmovtuc\fR as though a shorter string length
were specified which did not imply potential overlap.  Thus this
instruction which is in the inner loop of \fIprintf\fR on the 4bsd
tape, and which works fine on an 11/780, malfunctions on an 11/750
causing strange and awful behavior.
.IP \s+1\(bu\s0 4
(The following change is applicable only to systems bootstrapped
from the 4.1bsd release tape; systems upgraded from 4.0bsd may
or may not include this change.)
The standard i/o library has been made more compatible with the PDP-11
version 7 system and now supports concurrent read and write access
to files (see
.IR fopen (3s)
for details).
This caused a change in an internal data structure which is visible
to compiled programs through the macros in <stdio.h>, and thus
necessitates discarding of old \fB.o\fR files and recompilation.
Note that this standard i/o library now replaces the old \fB\-lNS\fR
library which was in 3bsd but was deleted from 4bsd pending the
inclusion of read-write capability in stdio.  
.SH
.LG
.ce
Section 1
.SM
.sp
.PP
.de BP
.IP \fB\\$1\\fR 11n
..
.BP adb
A bug which prevented programs loaded with the \fB\-N\fR loader
option from having breakpoints set on them has been fixed.
A bug which prevented backtraces of programs which are stopped
at interrupt level (after a signal) has been fixed by teaching
adb how to step across the interrupt stack frame.
The system now makes available and the $? command in adb interprets
more precise codes when SIGILL and SIGFPE exceptions occur.
Thus if you divide by zero, you can find out that this was what
caused a floating point exception.
A bug which prevented format
repetition counts (e.g. the 10 in ``0/10X'') from working
has been fixed.
A bug related to adb has been fixed that prevented any sensible
traceback after a FORTRAN-77 runtime error which trapped
an exception or fault (e.g. a floating point divide by 0).
A bug which caused the maps to be set improperly when debugging
the kernel on a crash dump has been fixed.
.IP
New commands have been added to adb to facilitate writing adb procedures
stored in files:  see the descriptions of $<<, the register <9,
and the # operator in the revised adb manual page.
.BP awk
Has moved from /usr/bin to /bin because it is needed during
bootstrap procedures.
.BP bc
Now takes the new C syntax operators: ``=op'' as well as
(for history's sake) the old syntax ``op=''.
.BP calendar
Several bugs have been fixed in the internals of the calendar program.
In addition it is now possible to have a calendar entry consisting
of merely a date (with no month specified) and have this entry occur
each month.
.BP cc
A bug has been fixed in the C optimizer which caused strange
things to happen when long variable names were used.
The size of the internal ``dimension'' table has been increased
to allow more structure fields to be declared.
A problem which caused the compiler to print ``expression causes
compiler loop'' when structure assignment was embedded in an
expression context has been fixed.  A bug in the code generator
tables which affected certain FORTRAN constructs has also been fixed.
.BP checknr
Es versteht \fB\-mm\fR.
.BP csh
A cosmetic bug which prevented the distributed source from compiling
has been fixed.  A bug which caused argument lists including the strings
``{'' or ``{}'' to sometimes fail saying ``No match'' has been fixed.
A bug which caused a strange state to result when a command of the
form ``(a; b; c)'' was stopped from the keyboard has been fixed.
The shell has been fixed so that it prefers to make stopped jobs
the new current jobs after the current job has terminated.
The construct ``${TERM}'' no longer yields an extra ``}''
when the variable expanded is from the environment.
.IP
Previously undocumented was the shell variable \fIhistchars\fR;
it can be set to two characters, and the first is then a replacement
for the normal \fB!\fR history character and the second for the \fB^\fR
quick history substitution character.  Thus after ``set histchars=,;''
the command ``,,'' repeats the previous command, as ``!!'' would normally
have done.
.BP ctags
Now takes an option
.B \-v
to produce output suitable for input to
.IR vgrind (1).
.BP cu
Now honors uucp's locking protocol for the dialout lines.
Several bugs relating to internal buffer overruns have been fixed.
An option \fB\-b\fR has been added which causes the BREAK key
to generate breaks (by turning input null characters into breaks
sent over the line).
.BP delivermail
.br
Some bugs which caused strange loops when aliases were self-referential
have been fixed.
.BP diff
Some bugs related to directory diffs when the
.B \-h
option was used have been fixed; previously the
.B \-h
option was non-functional.
.BP dump
An obnoxious bug in the dump program where it would wrongly
suggest that further dump tapes were needed after a multi-tape
dump had already completed has been fixed.  The dump program
no longer attempts to time tape rewinds itself, but uses
a mechanism which does not depend on the speed of the tape
drive to determine when a rewind is complete.
.BP error
Has been taught about the error message formats of the
PDP-11 C compiler.
.BP expand
A internal error check which was incorrect has been fixed.
.BP f77
Has had a bug fixed which caused some block data subroutines
and main programs to not compile (the sympton was a diagnostic of
the form ``Undefined: LWM%d''.  A number of minor bugs which
combined to make sdb function poorly with f77 have been fixed.
The result of these bugs were that if file names were longer
than 6 characters sdb could not read the symbol table of the
resulting FORTRAN binary.
.IP
An i/o library bug which caused numbers of the form ``-1.2''
to convert improperly in list-directed input (reading as ``-0.8'',
taking the mantissa as positive) has been fixed.
.BP ld
If you are using the \fB\-r\fR flag and there remain undefined symbols
you no longer get a spurious error return.  Now respects modes of existing
files and your file-creation mask more.
.BP lisp
The functions +, /, -, *, 1+, 1- now expect fixnum arguments,
for interpreted functons as well as compiled ones.  The source
for the VMS and UNIX versions of lisp have been combined and
synchronized.  The construction of very large integers has
been altered to use regular dotted pairs in a non-standard
way, so that fewer garbage collections will occur.  (It is no
longer safe to use ``car'' and ``cdr'' to disect large
integers).  Mixed-mode arithmetic has been made faster.
There is a new compiler option (liszt -r) which allows
you to create
.B small
lisp application programs (with a mechanism other than
``dumplisp'', which tends to create very large binaries).
When the result of
such a compilation is executed directly, it execs /usr/ucb/lisp
and then fast loads the file you asked to be executed.
A new flag $ldprint has been added to control the printing
of fasl/load messages.
New functions (purecopy), (getdata), (putdata),
and (removeaddress) have been added.
A number of minor bugs have been fixed.
.BP lpr
Has been modified to work on both DECWRITER type devices
at 1200 baud masquerading as printers and also on real line
printers.  The queueing algorithm has been made first-come-first-serve
(replacing the old random job first algorithm), and a line
printer driver is now available in the standard distributed system.
.BP ls
A bug has been fixed which caused essentially random numbers to
be printed for the size of special files.  The size now prints as 0.
.BP make
A spelling error has been fixed which had the variable EC initialized
to f77 rather than FC=f77.
.BP man
A bug which caused it to core dump when reformatting a manual page
whose source macros were inaccessible has been fixed.
.BP mt
Is a new command
which provides easy access to operations such as forward and backward spacing
of files and records on magnetic tape.
.BP mv
Has been changed to have a option ``\fB\-\fR'' which means that
all the following arguments are file names.  A bug has been fixed
which caused strange behaviour when the \fB\-i\fR option was used
on directories.
A bug which prevented renaming of subdirectories to which you had no
write access has been fixed.
.BP oldcsh
Which was non-functional due to a change in a internal library
interface which it had taken advantage of has been fixed to work.
.BP od
New options \fBO\fR, \fBX\fR, and \fBD\fR print 32 bit integers
in octal hex and decimal format; an option \fBw\fR has been
added to cause 132 column output rather than the default 80 column
oriented output.
.BP pc/pi
A number of bugs in the sdb symbol table produced have been fixed.
Structured types may now exceed 65k bytes in size, but in that case
may not be passed by value nor assigned by simple assignment.
Structured types are properly returned from recursive functions.
Minor bugs in passing function parameters have been fixed, and
there still exist some more minor bugs here.
Runtime tests can be now be enabled or disabled on a per routine basis.
Runtime checks are now done properly on builtin functions.
Warnings (or standards violations) are now produced for extensions
to the language.  Some inconsistencies in dealing with running out of
memory have been fixed.
.IP
Some bugs are known: invoking a formal routine from inside a formal
invocation of the same routine will mess up.
In pc only: linking seperately compiled modules from other than the 
current directory only works if you give full path names (or the same
relative paths) for the compilation and the linking.
.IP
Some changes are planned soon:
for-loop variables and with pointers will be allocated to registers.
The formal routine syntax is currently as in Jensen and Wirth, but
will soon be changed to the the syntax of the proposed standards,
in which parameters to formals must be given.
It is planned that \fBpc\fR will soon do compile time constant folding.
.BP pmerge
Is a new program which can convert large Pascal programs back into a
single file, eliminating the header files and separate source files
normally used for separate compilation.
.BP prof
A bug which caused prof to loop when a file-static function was
profiled has been fixed.  A bug in the kernel which caused the
results of prof to be inaccurate has also been fixed.
.BP ps
Has been changed to work with the new kernel and is no longer
dependent on system sizing; thus it is no longer necessary to
recompile ps when the system tables are made larger.  A bug
in the \fBs\fR option which caused the computed stack size
to be a constant 512 bytes too large has been fixed.
The ``STAT'' field now shows ``>'' in the second position for programs
which are using more memory than their \fImemoryuse\fR limit (see
.IR vlimit (2)).
It also shows ``S'' in the fourth position for processes which have
declared themselves to be strongly sequential (see
.IR vadvise (2)).
Under the \fBv\fR option, the SWRSS field has been replaced by a new
field ``LIM'' which shows the limit on \fImemoryuse\fR if there is a limit,
or \fIxx\fR if there is not.
.BP px
Is now written in C, is much more portable, and shares the runtime library
used by the compiler.   It is, unfortunately, somewhat slower now.
.BP ranlib
No longer considers it a fatal error that an archive member defines
no symbols.
.BP reset
Has been changed to invoke the command
.RS
.IP
.B "tset \-Q \-I"
.RE
.IP
so that all terminal modes will be reset.
.BP rm
Now has a
.B \-
option to indicate that all the following
parameters are to be treated as file names.
It can be used when file names begin with ``\fB\-''.
.BP rmdir
Now works correctly when arguments end in one or more ``/'' characters.
.BP sdb
Has been fixed to be able to deal with ``interrupt-stack-frames'',
so that it is possible to set breakpoints on and get backtraces
from routines called while a signal is being processed.
Now handles binaries which are mode 0407 (resulting from ``ld \-N'')
properly.
.BP sh
Has been changed so that ``#'' begins a comment.
Shell scripts to be executed by /bin/sh should begin
``#! /bin/sh'' on the first line.
.BP tar
Now defaults to blocked tape and can update blocked tapes (finally!).
When reading tape tar defaults to the raw tape and figures out
what is going on with blocksize so it need not be specified.
Thus the only commands which should be needed are the simple ``tar t'',
``tar c'', ``tar u'' and ``tar x''.
.BP uusend
Now uses the \fB\-r\fR option of \fIuux\fR to prevent presenting
extreme load to the connected system.
.BP vmstat
Has been changed so that the system's device names are printed
for the disks rather than D0, D1, D2, D3.  The old format output
of the 
.B \-i
option is no longer available.
.IP
The fields related to paging activity are now all
given in pages (of 1024 bytes).  In particular, the fields ``pi''
and ``po'' which previously showed the number of pagein and pageout
events now show pages, and ``sr'' which previously gave the clock
scan rate in revolutions-per-minute now gives the scan rate in pages
scanned per second.  To provide the extra space needed to present this
information, the swap in/out information, which was only marginally
interesting, is no longer printed.
.BP w
Has been modified so that it no longer needs to be recompiled
when the kernel tables change in size.
.BP wall
Now checks that the message is not too long for its internal buffer,
rather than just overrunning the buffer.  It handles running out
of processes by pausing, so it is possible to use it when there
are more than 25 users logged in and you are not the super-user.
It also gives the machine name you are on in the broadcast messages.
.BP who
``Who am I'' now prints your machine and login name (the first
word of its output) in a format suitable for use with uucp.
.BP write
Now checks that you do not have write permission disabled
and doesn't let you write to someone if they can't write back.
.SH
.LG
.ce
Section 2.
.SM
.sp
.BP intro
Now correctly reflects that argument lists may be upto 10240 characters
long.
.BP exec
Has been changed so that if a file being executed
begins with the magic characters #!, the rest of the line is understood
to be the name of an interpreter for the executed file.
Previously (and in fact still) the shell did much of this job;
it automatically executed itself on a text file with executable mode
when the text file's name was typed as a command.
Putting the facility into the system gives the following
benefits.
.RS
.IP 1)
It makes shell scripts more like real executable files,
because they can be the subject of 'exec.'
.IP 2)
If you do a 'ps' while such a command is running, its real
name appears instead of 'sh'.
Likewise, accounting is done on the basis of the real name.
.IP 3)
Shell scripts can be set-user-ID.
.IP 4)
It is simpler to have alternate shells available;
e.g. if you like the Berkeley \fIcsh\fR there is no question about
which shell is to interpret a file.
.IP 5)
It will allow other interpreters to fit in more smoothly.
.RE
.IP
To take advantage of this wonderful opportunity,
put
.DS
#! /bin/sh
.DE
.IP
at the left margin of the first line of your shell scripts.
Blanks after ! are OK.  Use a complete pathname (no search is done).
At the moment the whole line is restricted to 32 characters.
A single argument may be specified for the interpreter, thus:
.DS
#! /bin/csh  \-f
.DE
.IP
is very useful, avoiding reading \fI.cshrc\fR which is often
not wanted.
.BP kill
Has been changed so that when broadcasting signals universally
the signal being broadcast is not sent to the broadcaster.
This is used by the
.IR halt (8),
.IR shutdown (8),
and
.IR reboot (8)
commands.
.BP reboot
Has been changed to reflect the now more limited number
of option flags available to the system call due to the
nature of the console interface on the VAX 11/750.
.BP sigsys
Reflects the fact that the system now passes in to a signal
handler an indication of what exception really happened when
a SIGFPE or SIGILL is generated.  The call interface at the
point of a signal handler call is now specified.
.PP
.SH
.LG
.ce
Section 3
.SM
.sp
.PP
.BP curses
A large number of bug fixes have been incorporated,
and the documentation has been greatly improved.
The library is now much more solid than that originally distributed.
.BP fopen
Reflects the new open options which allow simultaneous read-write
to files; these extensions are being incorporated to bring
compatibility with the standard version 7 PDP-11 UNIX and to
replace the (now defunct) \fB\-lNS\fR.
.BP printf
A bug in the documentation which incorrectly stated that a %c format
would not put out a null character has been fixed.
.SH
.LG
.ce
Section 4
.SM
.sp
.PP
The system now supports a number of new devices and has capability
for detecting the device's presence and interrupt vectors at boot time.
The system also has capability to do device location at boot time
so that a system description as supplied to
.IR config (8)
can take advantage of available hardware redundancy.
.PP
Each configurable device driver in this section now includes
a SYNOPSIS giving sample lines to be included in a system
configuration.  Drivers also indicate the error messages
which they produce and describe each error.
.PP
.BP ct
A driver for a C/A/T phototypesetter interface.
.BP dh
Now includes handling of dm-11 modem control hardware.
Optional flags to the configuration program can also be
given to supply hardware carrier easily for lines where
wiring is inadequate.
.BP hp
Includes rm80 support.
.BP lp
Drives standard line printers, and has been improved to
cut the interrupt load by a factor of 20.
.BP mt
Describes the standard tape drive interface, which now includes
.B ioctl
operations for raw magtape allowing such standard operations
as forward and backward spacing over files and records, writing
of end-of-file marks, rewinds, rewinding and offlining,
and sensing of tape status.
These operations are used by the
.IR mt (1)
program which can be used to easily manipulate tape files,
and by the
.IR tar (1)
program to allow updates to blocked tapes.
.BP tm
Supports the UNIBUS TM/11 emulating tape controllers (e.g. EMULEX TC-11
with a KENNEDY 9300 drive).
.BP ts
Supports the UNIBUS TS/11 tape drive and transport.
.BP tty
Now provides a LDECCTLQ option which causes ^S and ^Q to function
as necessary for the VT100 to work properly.
.BP up
A driver for a EMULEX SC-11 or SC-21 UNIBUS disk controller
with storage module (e.g. Ampex 9300) disk drives.
.BP va
A varian raster plotter.
.SH
.LG
.ce
Section 5
.SM
.sp
.ce
No changes.
.SH
.LG
.ce
Section 6
.SM
.sp
.PP
.BP chase
Is a game where robots try to eat you.
.BP hangman
Is now screen oriented.
.BP rain
Drops keep falling on my head.
.BP rogue
Is a new and very popular screen-oriented game,
see
.IR rogue (6)
or
``A Guide to the Dungeons of Doom.''
.BP worm
Is a game where you see how long you can get the worm to grow.
.BP worms
Is an amusement where the worms chase each other around the screen.
.SH
.LG
.ce
Section 7
.SM
.sp
.ce
No changes.
.SH
.LG
.ce
Section 8
.SM
.NL
.PP
Major changes affecting system operations include:
.IP *
The system is configured from a single per-cpu specification
file which includes all locally relevant information: desired
devices, size of the maximum user load, timezone information, etc.
The system determines at boot time the size of the file system
buffer cache based on the amount of physical memory available
and sizes the system data structures based on the specification
of the maximum number of active users; it is no longer necessary
to juggle an armful of constants to enlarge the system.
The sizes of system tables are no longer compiled into programs
such as
.B ps
and
.B w.
.IP *
System error log information is saved across system crashes provided
no power failure occurs, as the error log is kept in-core in the
last 1024 bytes of memory.
.\"Error messages to the console are in a new standard format, reminiscent
.\"of Dave Presotto's speech pattern... they begin with a word, a laugh
.\"encoded as `:' and go on wittily from there to speak the truth.
Error messages to the console are in a standard format, of the form:
.RS
device: message
.RE
.IP
Messages have error registers decoded as bits, so that they are
readable, and no-longer refer to devices by their major/minor device
numbers, rather using device names.  Error messages about file
system problems (device full, out of inodes, etc) are referred to
with the mounted file system name, and a message is sent directly
to a user if his/her process writes to a file system when it is full.
All error diagnostics printed by drivers are documented in section 4
of the manual.
.IP *
DEC standard bad block forwarding is supported on all DEC disks
except the RP06; the code which implements this can be easily
moved into the drivers for the UNIBUS storage module disks; this is planned.
.IP *
Core dumps are saved after system crashes automatically as the system
writes a core image to a portion of the swap area from which it
is recovered after reboot.  The system then transfers these core
images to a specified UNIX directory, saving also the version of
the system associated with the crash.  The system also maintains
an error log
.B /usr/adm/shutdownlog
which records all system crashes and reboots with the information
about the causes.
.sp
.PP
.BP analyze
Now has an option
.B \-u
to print page numbers of the u. areas.
A bug which prevented the distributed
.B analyze
from working has been fixed.
.BP bad144
Is a new program which prints out the DEC-standard bad block
information for a disk, or puts it back if it gets clobbered.
The name of the program comes from the fact that the program
deals with ``DEC standard 144'' format.
.BP badsect
Creates a file in a file system which contains a specified disk
sector of that file system.  This is a primitive way of dealing
with bad sectors, but works on drivers which don't (yet) have bad
block forwarding according to the standard.
.BP getty
No longer prints ``Virtual'' in front of the system
identification, since there are no swap systems in sight anymore.
.BP halt
Now properly shuts down the system; see \fBreboot\fR below for details.
.BP icheck
Now properly sets the \fItfree\fR field in the super-block.
.BP init
Now interacts with \fBhalt\fR, \fBreboot\fR and \fBshutdown\fR
to bring about orderly system shutdowns.
No longer writes entries in the /usr/adm/wtmp accounting file when
a \fIgetty\fR process dies without a user logging in on a terminal.
Prints a warning message (on the console) if a terminal exists,
is enabled, but the open returns an error, and waits for terminal
to be openable, checking each minute, to prevent thrashing in this case.
.BP last
Now distinguishes between system shutdowns and system crashes.
.BP lastcomm
A bug causing a core dump if user id's not present in the
password file were encountered has been fixed.
.BP login
Now interacts with the shutdown command to forbid logins (except
by the super-user) in the last 5 minutes before a shutdown (detected
by the presence of the file /etc/nologin, which also contains a
message about why the system is shutting down which is presented
to the rejected users.)
Implements a notion of ``secure terminals''; if the file /etc/securetty
exists, then it should contain a list of the secure terminals
where root is allowed to login.  If this file does not exist,
then root can log in anywhere, as before.
If a user tries to login but can't get to their home directory
they are left in the root directory and warned, so that they
have some chance to send mail about or fix the problem themselves.
If a file \fI.hushlogin\fR exists in a users home directory
the the message of the day and other such information designed for
human users will not be printed at login time.  This is specifically
designed for the user \fIuucp\fR which is another computer
and just ignores such stuff anyways.
Finally a bug has been fixed which cause \fBlogin\fR to core
dump if there were tabs in the file /etc/ttytype.
.BP mkfs
Now works properly when given a \fIproto\fR argument;
previously it complained because it didn't know that the format
of the file /usr/mdec/uboot had been changed.
.BP pstat
Has new flags \fB\-m\fR and \fB\-g\fR which interpret the multiplexor
data structures.
.BP reboot
Now shuts the system down cleanly, stopping all system activity before
initiating the reboot procedure.  Normally, however, the new
.B shutdown 
command is used to take the system down, notifying the users of the
impending downtime.
The options
.B \-s
and
.B \-a
options to reboot are no longer available, as it will not be
possible to provide them on all VAX cpu's due to the way the
console interface works.  Instead, you can halt the processor
using
.B halt
which puts the system into a tight loop, and then perform the
desired reboot sequence manually at the console.  This works
on both 11/750 and 11/780 processors.
.BP renice
Has been modified for the new kernel and is no longer dependent
on system configuration parameters; it no longer
needs to be recompiled when system table sizes change.
.BP restor
Now properly handles the case where dump files are contained
in dump tapes; previously the end of the embedded dump would
confuse \fBrestor\fR and cause the rest of the dump tape to be
inaccessible.
.BP sa
Now correctly handles an arbitrary number of commands and users.
Two new options have been added \fB\-v\fR and \fB\-f\fR giving
it a googol+2 options.  See
.IR sa (8)
for details.
.BP savecore
Is a new program which runs after a reboot to save
check to see if the system had crashed and, if it had,
to save any core image which was successfully written to
the paging area.
See
.IR savecore (8)
for a full description.
.BP shutdown
Is a new command which shuts the system down at a specified time.
It broadcasts messages to users warning them as the downtime approaches,
records the reason for the reboot in a log file,
and cooperates with init in a cleanly shutdown (e.g. during
the last 2 minutes of system operation, users attempting
to log in are told that the system is going down and the reason
for the shutdown but not allowed to log in.)