Re: 'rmm' (or 'trash') script

From: Kevin Pfeiffer (pfeiffer_at_iu-bremen.de)
Date: 10/25/03

  • Next message: Dan Muey: "Custom rmodule with use strict;" 
    To: beginners@perl.org
Date: Sat, 25 Oct 2003 12:17:37 +0200

    Hi David,

    In article <20031024235500.94798.qmail@onion.perl.org>, David wrote:

    > Kevin Pfeiffer wrote:
    >
    >> Hi all,
    >>
    >> I just took another look at an exercise I wrote a couple months ago and
    >> fleshed it out a bit. It is a commandline "trashcan" program which I
    >> actually use. Instead of typing 'rm' I almost always use 'rmm' now.
    >>
    >> It's meant to be used in a "friendly" environment, nonetheless, if anyone
    >> sees any potentials for error (or suggestions for better work) please say
    >> so...
    >>
    >
    > i didn't read your whole script, only the first 20 lines or so and i have
    > a few suggestions:
    >
    > 1. you have:
    >
    > if ($ARGV[0] =~ /^-(.)$/) {
    >
    > can your program handle files starting with a '-'? it's legal in *nix for
    > file names to begin with a '-':
    [...]
    > i understand that you can still supply files to rmm starting with '-'
    > like:
    >
    > [panda]$ rmm ./-remove-this-file
    > [panda]$ rmm /home/dzhuo/-remove-this-file
    >
    > but i think it's still nice (maybe) to be able to just:
    >
    > [panda]$ rmm -remove-this-file

    You would have to escape the dash: 'rmm --remove-this-file'.

    I don't see how even GetOpts can cover all possibilities. How do you
    distinguish between 'rmm -l' (list contents of trash) and 'rmm -l' (delete
    a file named "-l")? (Other than by having to escape these possibilities.)

    > 2. you have:
    >
    > ($trash_dir) or die "Error: No trash directory defined!\n";
    >
    > which means you will not allow user to name his/her trash directory '0'?
    > for a general utility program like your rmm, you should relax this
    > restriction. btw, $trash_dir is hard coded in your script so how can it
    > ever be false?

    It's not meant to be changed, though as you mention, one could modify the
    script. It's meant more as a protection to ensure that a trash dir has been
    set, so that one doesn't accidentally issue a delete all command in
    $ENV{HOME}/.

    >
    > 3. you have:
    >
    > $path =~ /.*\..+$/ or die "Name of trash directory must begin with a dot
    > followed by one or more letters!\n";
    >
    > your regex does not match your die message.

    Oops!
     
    > 4. you have:
    >
    > unless (-e $path) {
    > print "Creating trash directory: $path\n";
    > mkdir $path or die "Couldn't create $path: $!\n";
    > }
    >
    > don't do this for a general utility program where your program might be
    > involved very often from different scripts. you have a race condition. do
    > something similar to the following instead:
    >
    > [panda]$ perl -MErrno -e 'die $! unless(mkdir('foo') || $!{EEXIST});'

    This says "die unless you can mkdir or you get an error message that it
    already exists"? I understand your point, but in this situation (creating a
    trash directory) I don't see the danger. If I try mkdir on an already
    existing directory I get the error message that it already exists. So if I
    check for the existence, then try to mkdir and in between another process
    has created the same directory, won't I simply get an error message that
    the dir already exists? I've made the change, but am trying to follow the
    reasoning in this particular case.

    [...]
    > 6. see if Fild::Find can help you simplify some of your dir scanning code.

    I also just noticed that my glob did not handle dot-files (.my_file). I've
    fixed this.
     
    > 7. it will be nice to set a limit on how big your trash dir can be.
    > otherwise, it's easy for people to give putting stuff into it and forget
    > about how big it has grown to.

    Sounds good; perhaps also a possible auto-empty function. I also want to add
    commandline completion for restoring files (moving them out of the trash) -
    or else a down/up arrow function that scrolls through the list of files.

    Thanks for your help and advice!

    -K 

    -- 
Kevin Pfeiffer
  • Next message: Dan Muey: "Custom rmodule with use strict;"

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