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Gregg M. Townsend
Department of Computer Science
The University of Arizona
www.cs.arizona.edu/icon/uguide/files.htm
Last updated November 16, 2009
Version 9.4 of Icon introduced several changes to the organization of Icon's files under Unix and the methods for finding them. These changes, which are described below, simplify the installation and use of Icon.
As Icon evolved, the procedures from the Icon program library became more important to basic Icon programs, and vital to graphics programs; yet the IPL had been treated as a separate product. A complete Icon system required two downloads and two installation efforts, with proper coordination.
Now, the complete set of basic and graphics library
procedures is included with every binary Icon distribution.
Also present are the associated $include files
and a selected few programs from the library —
notably VIB, the visual interface builder.
Source distributions of Icon include the full library, which also continues to be available separately.
An Icon binary distribution unpacks to produce an icon
directory containing bin, lib, man,
and doc subdirectories.
Building Icon from source produces these same directories.
The bin directory contains executables of
icont, the Icon translator;
iconx, the Icon interpreter;
a few library programs including vib;
and libcfunc.so, the loadable C functions.
There is a symbolic link from icon to icont.
Files in this directory are system dependent.
The lib directory holds $include files
and "ucode" (.u1/.u2) files of
program library procedures.
This directory is system independent.
The man directory holds the Unix man pages
for icon and icont, and the doc
directory holds HTML (.htm) documentation files.
These directories are also system independent.
This structure is similar to that of binary distributions of Icon 9.3.
The main difference is that the lib directory no longer holds
just a subset of the procedure collection, and the few files from
the former include directory have moved into lib.
The icon directory can be installed in any public or
private area as long as its internal structure is preserved.
When upgrading an existing Icon installation, replacing the previous
Icon directory with the new one may provide the smoothest transition.
Old Icon binaries will continue to function correctly with the new
interpreter.
In order to consider packaging Icon binaries in Linux RPM files,
or other similar packages, it is necessary to define a "canonical"
location for installing Icon.
The suggested canonical system installation location for Icon is
/opt/icon.
The /opt directory is present today on most Unix systems and is
the location recommended by the emerging File Hierarchy Standard (FHS),
www.pathname.com/fhs.
For convenience of use it may be desirable to provide symbolic
links from a directory such as /opt/bin or /usr/local/bin
to programs in the Icon bin directory.
If this is done, the list should include at least icon,
icont, iconx, and vib.
iconx location Past versions of icont were configured to know
the location of iconx in order to embed this in
generated binaries.
The iconx location was configured by editing
src/h/path.h in source builds or by using the
patchstr utility to edit the icont
executable when installing a binary distribution.
Now, icont deduces its own location,
and from this it infers the location of iconx
in the same directory.
No configuration of icont is needed, and the correct
path is embedded automatically, requiring only that
icont and iconx reside in the same directory.
It is still possible to configure a fixed path in
icont using the patchstr utility.
If this is done, the configured path is used instead of the
inferred path.
The path that icont embeds in an Icon executable makes
binary distributions of Icon programs difficult because the embedded
path must be edited to match the installed location of iconx.
The ipatch utility performed this task when installing
binary distributions of Icon 9.3.
Icon implements a simple search in the shell script that
heads each generated Icon executable.
The new header script searches for iconx
in these places:
icont or as patched later)
The second item is the key: If there is a copy of iconx
in the same directory as the executing program, it is found automatically
and used as the interpreter.
An Icon program can now be distributed in binary form
simply by including an iconx executable
in the same directory as the program executable.
The ipatch utility has been modified to recognize
both old and new headers, and can still be used to edit the path
embedded in an Icon executable.
The ability to figure out its own location also lets
icont provide automatic access to library procedures.
The inferred location of the lib directory is implicitly
appended to the paths, if any, specified by LPATH and IPATH
environment variables.
To use only the standard library files, no environment variables
need be set.
In a similar manner, iconx creates or alters the
FPATH environment variable before beginning execution of an Icon
program. This provides transparent access to the library's
loadable C functions without requiring explicit user action.
With the changes above, the executable files in an Icon binary
distribution are ready for use without modification.
The annoying and error-prone Setup step that was necessary
with previous versions is no longer required.
Now, installation can be as simple as just unpacking the
tar file and adding its bin directory to the search path.