In order to make a build system in Felix we first need some sane tools for
first order operations
on files (copying, etc). I consider Unix tools arcane and unprincipled,
and of course they don't work on Windows.
I would appreciate help designing the toolset. Here's what I have (almost) now:
flx_ls dir pattern
flx_rm dir pattern [--test]
flx_cp src-dir src-pattern dst-spec [--test]
The first command looks in directory dir for all regular files whose names
relative to dir match
Perl regexp pattern and deletes them. If --test is specified it just prints
what it will do without doing it.
This operation will not delete directories or other special files, including
symlinks. Directories . and .. are
ignored.
In principle the model I'm using is that directories "do not exist".
For example
x .* matches x/a.c x/d/a.c
x [^/]* match x/a.c but not x/d/a.c
x \.flx match x/a.flx x/d/b.flx but not x/a.c
This matching mechanism is much saner than shell willcards and recursion
switches, and a lot
more powerful. The principal drawback is that Perl regexps use characters that
the shell interprets
so some quoting is required ;(
The command flx_cp is a sane file copy. It searches the same way flx_rm does
but uses
the destination pattern as a target, with \1 \2 etc being replaced by match
groups from
the src-pattern. [$ may have been a saner choice .. :]
This command guarantees not to clobber any of the files: no copies on top of a
source
file are allow, nor may two files be copied to the same target. The target file
can exist, however,
and will be overwritten. Time stamps etc are not preserved (the file is copied
by ordinary
C function calls so the copy is just a new file each time).
If the target file specifies a file in a directory the directory is created
automatically.
Thus, you can do this:
flx_cp felix '(.*\.flx)' 'backup/\'
and the whole tree of *.flx files located in directory felix will be copied
into directory backup.
NOTE: at present, flx_cp and "flx flx_cp" do not work the same. This is due to
a bug
in flx in that it calls the shell to execute external commands, using C
function "system()".
This means test is parsed by the shell TWICE once going into flx and once call
in system, and so quoting is messed up. I plan to fix this by using either
posix_spawn
or a horrible home-brew fork()/exec() function, to ensure words parsed by the
shell
are not parsed again (but preserved as words). Unfortunately the command line
parsing done by flx uses string concatenation and will have to be changed to use
word lists.
Anyhow: apart from flx_rm and flx_cp we clearly need flx_mv, again with the
guarantee to preserve all data. We also need a way to prune empty directories,
say flx_rmdir.
So .. the *basic* idea is to get rid of the notion of directories as such, and
instead just
consider a set of regular files with structured names, and use regexps to work
with those
names.
A few other tools like "rsynch d1 d2" make sense.
And one I'd really like: global search and replace over a set of files!
Anyhow, the question is: what is a minimal fully functional set of file
management tools?
Note that most of these tools will be be library functions plus wrappers so
that it is possible
to manipulate the file system easily inside a program.
--
john skaller
[email protected]
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