jbc@ut-sally.UUCP (08/07/83)
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of such topics as: installation and configuration; sources
and documentation; groups and identifiers; file systems;
interprocess communications; networks; performance
(including some tentative benchmarks); and vendor support.
Common features are mostly left to the manuals, in
order to better concentrate on differences. This is meant
to be a _q_u_a_l_i_t_a_t_i_v_e comparison, intended to serve only as a
guide for further study.
1. Introduction
1.1 Intent
This paper describes certain differences between
System V and 4.1C BSD, leaving details of common functions
to the manuals. This is a _q_u_a_l_i_t_a_t_i_v_e comparison, intended
to serve only as a guide for further study.
While performance is not a major theme of this paper,
some tentative benchmarks are included to indicate the
relative performance of the two systems. These benchmarks
should not be considered conclusive, since 4.1C is not 4.2
and since we have not had sufficient production experience
with System V.
This paper supersedes a previous paper, ``UNIX
System III and 4.1BSD, A Practical Comparison'', by the same
authors. In some cases, features are noted herein as having
been introduced in System V or 4.1C BSD when they were
actually introduced in System III or 4.1BSD. This usually
occurs when comparisons are being made with V7/32V and is
done simply to decrease the verbiage.
1.2 Format of the Paper
The first section following the Introduction contains
subsections corresponding to sections of the _U_N_I_X
_P_r_o_g_r_a_m_m_e_r'_s _M_a_n_u_a_l* in order to provide a framework for
comparison of detailed features of the operating systems.
There follow several sections on subjects which are
wider than a single manual entry or which we consider
important.
__________
* The 4.1C BSD title; see section on Documentation.
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Finally, there is a summary section which includes some
comments on recent cooperation among UNIX system developers.
1.3 Disclaimers and Acknowledgments
The authors of this paper are in no way affiliated with
the University of California, Bell Laboratories, or Western
Electric, and are solely responsible for the opinions
presented herein.
4.1C BSD is not a regular Berkeley Software
Distribution and inquiries should _n_o_t be sent to Berkeley
concerning it. Facilities in 4.1C may be represented
differently in 4.2. In cases in which we know what the
differences will be we have noted them but we do not claim
to have caught every case. When Berkeley is ready to
distribute 4.2BSD, they will announce it.
We would like to acknowledge Dr. Michael Molloy of the
Computer Science Department, University of Texas at Austin,
for the use of the departmental VAX-11/780 and for his
assistance, as well as Bill Lee of the U.T. Austin
Computation Center for his continued moral and material
support. We would also like to thank the following for
reviewing the paper: Sam Leffler of the University of
California at Berkeley, Nina McCloskey of AT&T Technology
and Licensing Division, Armando Stettner of DEC, Dan
Franklin of Bolt, Beranek, and Newman (BBN), and Doug Gwyn
of the U.S. Army Ballistic Research Laboratory (BRL).
2. Manual Sections
The subsections of this section generally follow the
order of the _U_N_I_X _P_r_o_g_r_a_m_m_e_r'_s _M_a_n_u_a_l.
2.1 Commands
The general utility commands supplied with the two
systems exhibit relatively minor differences, mainly in
terms of the options available. A few commands are included
in each distribution which do not occur in the other; many
of these are of questionable usefulness anyway and the
reader is referred to the manuals for further details.
Certain larger packages, however, such as language support
facilities, are rather different and are discussed in the
following sections.
2.1.1 _U_s_e_r__c_o_n_v_e_n_i_e_n_c_e Several utilities are considered
important for the convenience of the frequent user.
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Berkeley UNIX provides the _p_a_g_e and _m_o_r_e file perusal
commands, used to examine a file a screenful at a time. No
equivalent is available in Bell UNIX.
The Berkeley _l_s command understands proper multicolumn
formatting of a directory listing (when stdout is a tty).
Under System V, _l_s generates a listing with one entry per
line; a multicolumn listing must be obtained by piping the
output into the _p_a_s_t_e command, e.g.
ls | paste - - - - -
The Berkeley _w program may be used to monitor user
activity; the System V equivalent uses a command file,
/etc/whodo, to generate similar information. However, it is
rather inconvenient to have to specify the absolute pathname
and few users actually have /etc as part of their default
path. (We note, of course, that the superuser's PATH
environment variable _d_o_e_s include /etc, perhaps to suggest
that only system administrators and the like should be
interested in such information.)
2.1.2 _P_r_o_g_r_a_m_m_i_n_g__s_u_p_p_o_r_t__e_n_v_i_r_o_n_m_e_n_t_s Several changes
have been made to the C programming support environment
(_S_o_f_t_w_a_r_e _G_e_n_e_r_a_t_i_o_n _S_y_s_t_e_m in WECo parlance) in System V.
Most of the #include files have been rearranged and
expanded, and it is advisable to recompile all C programs.
_P_c_c, the portable C compiler, includes reasonable
enumerations, changes to structure and union handling
(nonunique structure member names), correct handling of the
void data type, and several bug fixes. The _c_c command
itself has added the W flag to allow options to be
explicitly specified for a particular compilation subpass.
Certain bugs which are known to remain are documented in the
_S_y_s_t_e_m _R_e_l_e_a_s_e _D_e_s_c_r_i_p_t_i_o_n.
Two new tools are included: _c_x_r_e_f, which generates
cross-reference listings and obsoletes both _c_r_e_f and _x_r_e_f,
and _c_f_l_o_w, which builds a graph of external references
occurring in a collection of assorted source files (C,
assembler, etc.).
The System V f77 programming support environment also
includes two new tools: _a_s_a interprets the standard ASA
carriage control characters, and _f_s_p_l_i_t may be used to split
FORTRAN sources (f77, efl, ratfor) on a procedure-per-file
basis. In addition, the load-time library has been greatly
extended and enhanced.
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The libraries for both C and f77 are available in
profiled versions, which must be loaded explicitly in place
of the default, non-profiled ones. These profiled libraries
allow program execution profiling at the library function
level rather than the user program function level.
Further, the symbolic debugger _s_d_b is very much
improved and may be used easily with either C or f77
programs.
The _a_s assembler and _l_d linker have been modified to
utilize the new Common Object File Format, which is
discussed below. Note that any change to a source file for
a program thus necessitates recompilation of all sources
before the objects may be relinked using _l_d, since the old
and new object formats are radically different.
The C compiler in 4.1C (_p_c_c) is very similar to the one
in System III, including void, union, enum, and structure
elements named per structure, some of which were added after
32V. Berkeley added very long identifiers in 4.1BSD, while
System III and System V retained the old 7/8 character
identifiers. The _a_s assembler, the _l_d linker, and
associated libraries are similar to the ones in 32V,
although in 4.1 _l_d was reworked to be four to five times
faster and this improvement is preserved in 4.1C and 4.2.
The _d_b_x symbolic debugger is new.
4.1C BSD has some bug fixes and other improvements to
_f_7_7 (an overlaid version of this compiler is available for
2.8bsd).
4.2 has an extensively reworked version of _f_7_7 and its
associated libraries: early versions of this new FORTRAN
package were apparently the source for the new System V
FORTRAN facilities.
Both systems support Ratfor and the Extended FORTRAN
Language (EFL), but 4.1C additionally provides the _s_t_r_u_c_t
utility, used to convert FORTRAN sources into reasonably
clean Ratfor.
System V has _b_s, essentially derived from _B_A_S_I_C. There
is no equivalent in 4.1C BSD; however, the University of
British Columbia _B_A_S_I_C sytem is compatible with 4BSD.
Similarly, System V includes the classic _s_n_o SNOBOL
system, while 4.1C includes _P_A_S_C_A_L, _F_R_A_N_Z _L_I_S_P, _A_P_L, and _f_p.
_A_P_L is a user contributed software package from Purdue. _F_p
(Functional Programming language compiler/interpreter)
implements the applicative language proposed by John Backus
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in his Turing award lecture. 4.2 may include _I_c_o_n as user
contributed software.
There is a _C_O_B_O_L compiler commercially available for
4BSD, and possibly for System V.
2.1.3 _S_h_e_l_l_s System V supports the Bourne shell (_s_h), with
few noticeable changes from V7. 4.1C BSD has much the same
Bourne shell plus the Cshell (_c_s_h), often a new user's first
command language.
The Cshell has most of the capabilities of the Bourne
shell (though the syntax is different), plus the history,
alias and directory stack features. History and alias allow
editing and replaying of saved commands. Such features are
the main reason many users prefer the Cshell (although some
cite its extensive C-like control structures as another
reason).
The 4.1C Cshell also has a set of job control features
(requiring the Berkeley `new tty' terminal driver) which
allow the user to suspend and resume subprocesses.
The 4.1C resource limitation facilities are normally
accessed via the _c_s_h _l_i_m_i_t command. The only close
equivalent in System V _s_h is the _u_l_i_m_i_t command, used to
control the size of the file a child process may write.
2.1.4 _F_o_r_m_a_t_t_i_n_g__a_n_d__t_y_p_e_s_e_t_t_i_n_g 4.1C offers the -me macro
package, while System V has the -mm package, somewhat
augmented from PWB. The -ms macros have been removed from
System V but are still found in 4.1C. In 4.2, they have
been extended to provide support for tables of contents and
the like.
System V includes additional macro support for
generating slides and viewgraphs.
An improved interface to the Versatec is provided in
System V, along with new _i_o_c_t_l calls for state control. The
_v_c_a_t filter for _t_r_o_f_f which was documented but absent in
System III seems to have disappeared entirely in System V.
Both systems have Versatec drivers expecting a single
interrupt address, whereas the Versatec itself has two
configured into the hardware. 4.1C at least has comments in
the code to tell you this (and #ifdefs to deal with it).
The 4.1 Versatec user programs expected a unit wide
enough to handle four pages abreast; this problem has been
fixed in 4.2 (but not 4.1C) by extensions to the printer