Stuck

Filed under Code by adam | August 7, 2005 | 9 comments

It seems to me there is a “free support gap” (that is, a gap in free support, not a support gap which is free), for users who are not beginners but are also not master developers—for example, myself. Just about any GNU/Linux question that arises that can be answered by a manpage or googling, I can figure out myself. But for trickier problems (for example, see my null oddity issue from yesterday), there doesn’t seem to be anywhere to go. Most of the helpful subscribers on debian-user are not much more knowledgeable than I am. I run my own linux-disciples list where I can answer most questions but seldom is there anyone to help out with my own questions. Similarly, there is a perl-beginners list, but no “perl-intermediate” or “perl-advanced” list. I’ve also not had much luck writing directly to developers with questions, outside of Debian.

Just a couple cases in point:

  • Using File::Find to follow symlinks — posted to perl beginners, but no response:

    I’d like to use File::Find, or some alternative, to follow symlinks; regardless of whether the file/directory has already been traversed in some other location. In other words, if there I have directories x and y, and the file a is in x and symlinked into y, I want the find &wanted function to be called on file a in both x and y.

    Possible? Do I have to write my own find function from scratch? None of the follow-find=> options seem to accomplish what I want.

    I’ve also noticed that the &wanted function is not called even *once* in some cases where there are duplicate symlink files (i.e., it is not even called on the “real” file). Switching from find to finddepth seems to fix this, but I really don’t understand what’s going on. Any pointers?

    Update: after discussing off-line with a helpful blog reader, I’ve isolated the problem to the following directory structure: 

     .: y/ ./y: 1/ 3/ a.jpg ./y/1: a.jpg -> (...full path...)/y/a.jpg ./y/3: 1 -> ../1

    In other words, a.jpg is in y/. There are two symlinks to that file, one directly — y/1/a.jpg ; the other indirectly, since y/3 contains a symlink to y/1. Perl’s find function only traverses the second instance, not the first. I would like it to do both.

  • growisofs problems — write fails frequently — there doesn’t seem to be any canonical mailing list or support for growisofs, so users are directed to Debian’s cdwrite list:

    I’m using growisofs from dvd+rw-tools 5.21.4.10.8-1 from Debian Sarge on an IBM Thinkpad X40 with a DVD writer that reports itself as: “MATSHITADVD-RAM UJ-812.”

    Sometimes I will try 10 or 15 times in a row to burn a DVD and it fails each time with something like:

    :-[ WRITE@LBA=1c970h failed with SK=4h/ASC=03h/ACQ=00h]: Input/output error
    builtin_dd: 117104*2KB out @ average 1.0x1385KBps
    :-( write failed: Input/output error
    /dev/dvd: flushing cache
    /dev/dvd: updating RMA
    /dev/dvd: closing disc
    :-[ CLOSE DISC failed with SK=5h/ASC=72h/ACQ=04h]: Input/output error
    /dev/dvd: reloading tray

    In this example, I had forced the write speed to 1 (it defaults to 2) to see if it makes any difference—it didn’t.

    I would suspect bad media, except that it seems to consistently fail in exactly the same place for a given DVD image to burn. For example, this one keeps failing at 6.13% done. Another failed repeatedly at 47.47%.

    Any ideas what’s going on? Troubleshooting tips? I hate to throw away so many DVDs.

Thus, I throw myself on the mercy of my readers, in particular the Planet Debian crowd. I’ve actually had more luck in the past posting questions to my blog and letting people come to me, rather than seeking out an appropriate forum to ask the question. There seems to something backwards about that.