Commands and Utilities Proposal, 0.2
Following is a revised and updated Commands and Utilities proposal. It
makes some minor changes to the older proposal, and includes a section
on individual command differences. It also includes a note on options
not specified by the standard.
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Linux Standard Base Commands and Utilities
Initial Proposal, v. 0.2
Introduction
------------
In an effort to maintain a commonality between Linux based operating systems
and other GNU-like operating systems, LSB uses as the basis for its command
and utility list the list of commands from the Single UNIX Specification,
version 2, also known as UNIX98. However, in some cases it is either not
possible for Linux based operating systems to comply and remain completely
Free Software/Open Source, and in other cases a different program is more
widely used on Linux based operating systems that provides the same
functionality. Those places where LSB diverges from UNIX98 are detailed here,
with rationale for each. For a listing of commands and utilities specified
by UNIX98, along with a link to descriptions of how each command should
operate and a note as to what package a Free Software/Open Source version of
that command is available, see http://www.linuxbase.org/cu/
Package Differences
-------------------
SCCS commands - admin, delta, get, prs, rmdel, sact, sccs, unget, val, what
Divergence: UNIX98 defines these commands as part of the Development
option. LSB defines them as Legacy Development commands.
Rationale: SCCS is not widely used on Linux-based platforms, and has
been widely replaced by RCS and CVS. No application should depend on
any of these commands being present, though.
Compression commands - compress, uncompress, zcat
Divergence: These commands are mandatory in UNIX98. LSB marks them as
Legacy. Instead, the commands gzip, gunzip, and zcat (from GNU Zip)
are mandatory.
Rationale: Compress uses a patented algorithm and is therefore tricky to
redistribute. GNU Zip is Free Software unencumbered by patents, and
also quite often produces better compression ratios than compress, as
well as being the current de facto standard for compressed file
distribution on Linux-based operating systems and other GNU-like
operating systems.
Archiving utilities - cpio, tar
Divergence: UNIX98 marks cpio and tar as legacy. LSB marks them as mandatory.
Rationale: The tar format is the de facto standard for software
distributed as source. It is important to be able to unpack this
source on Linux-based systems. Also, the cpio command can be used to
extract individual files from RPM files, which seems to be the current
de facto standard for binary software distribution.
Individual Command Differences
------------------------------
echo
SYNOPSIS
echo [-n] [-e] [string ...]
OPTIONS
-n Do not print a newline after string.
-e Enable escape characters.
NOTES
Default support for escape characters is implementation
dependant. In order to be sure that escape characters are
enabled, use the -e option. Use of command line options is not
portable outside of LSB.
Rationale:
UNIX98 specifies no options for echo. Linux has traditionally
supported both -n and -e, and it is expected that they are
supported. Also, the -n option is useful. UNIX98 recommends using
printf for maximum portability, as the System V and BSD versions of
echo differed in their interpretations of options. If portability is a
major concern, printf is recommended.
ln
SYNOPSIS
ln [-f] [-s] source_file target_file
ln [-f] [-s] source_file... target_dir
OPTIONS
-f Force existing destination pathnames to be removed to
allow the link.
-s Create a symbolic (or soft) link rather than a hard link.
NOTES
Use of the -s option is not portable outside of LSB.
Rationale:
UNIX98 doesn't specify the -s option. The Linux kernel has supported
symbolic links since (what, forever?). Symlinks are widely used on
Linux-based systems, and should be supported on all such sytems.
mail, mailx
The LSB mail command combines the specifications of UNIX98's mail and
mailx commands, providing the mailx functionality whenever the two
definitions conflict. This program must be available as both mail and
mailx.
Rationale:
The mailx argument -s is often passed to mail, and many other features
of mailx are usually assumed from mail. Note that passing arguments
specified in the mailx definition to mail is not portable outside of
LSB.
Global Differences
------------------
In addition to specific differense mentioned above, there are some
differences that take a global scope.
Command line options
Many of the open source implementations of these commands supply
options beyond those specified in UNIX98. In particular, most GNU
programs provide long options (options beginning with two dashes) such
as --help and --version. Applications should not depend on the
existance of any options not specified here or in UNIX98, or lack of
such options. The behavior of programs is not specified when passing
other options (for example, false --version may in fact use STDOUT and
return a true value).
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Comments and suggestions are of course welcome (I'm sure I've missed
something or other that someone will desperately want/need).
--
Jakob 'sparky' Kaivo - jkaivo@ndn.net - http://jakob.kaivo.net/
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