KPackagekit / aptitude woes... solved

Recently I was trying to make some updates to my Kubuntu 10.04 machine (where I do all my Rails development) and ran into a serious problem: both KPackagekit (KDE package manager) and aptitude were unable to even start.

KPackagekit gives:

"an unknown error has occurred"

or

"The package list needs to be rebuilt. 
This should have been done by the backend automatically"

aptitude gives:

E: Read error - read (5: Input/output error)
E: The package lists or status file could not be parsed or opened.

Turns out it was a "simple" problem -- Kpackagekit and aptitude are both based on the Debian APT package. That package manager has a built-in limit as to the amount of cache space that it supports. If you exceed that limit (by having a bunch of repositories and packages stored on disk in /var), then APT and its descendents just give up. The error messages above are indicative of this kind of error (and certainly aren't very descriptive).

The problem is that - once you get to this point - you can't do much of anything. Attempts to run either command just fail.

Searching for KPackagekit info yielded nothing useful, but when I searched on aptitude and its error message, I found the solution: increase the cache limit.

Here's the source of this information. The fix is simple; just run this command and then you should be OK.

sudo apt-get update -o APT::Cache-Limit=25165824

If you need, you can increase the Limit even further... it's only 24 megabytes which is nothing on today's systems.

Excel spreadsheets & Ruby => :tricky

I've been working on an ERP data conversion project, using Ruby to convert the data before it gets dumped into the Oracle database.  I only recently got involved to help out, and an earlier decision mandated that we produce our converted data in spreadsheets [I know, I know -- not what I would have decided, but they wanted folks to be able to easily manipulate the data].

Anyway, we're using the Spreadsheet gem which is pretty nice; however, it does have some limitations, which can result in oblique error messages such as the following:

ruby customer_fix_zip.rb
/Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:376:in `validate!': OLE2 signature is invalid (Ole::Storage::FormatError)
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:368:in `initialize'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:110:in `new'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:110:in `load'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:77:in `initialize'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:83:in `new'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/ruby-ole-1.2.11.1/lib/ole/storage/base.rb:83:in `open'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/spreadsheet-0.6.5.0/lib/spreadsheet/excel/reader.rb:1144:in `setup'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/spreadsheet-0.6.5.0/lib/spreadsheet/excel/reader.rb:121:in `read'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/spreadsheet-0.6.5.0/lib/spreadsheet/excel/workbook.rb:32:in `open'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/spreadsheet-0.6.5.0/lib/spreadsheet.rb:62:in `open'
    from /Users/jseidel/.rvm/gems/ruby-1.9.2-head/gems/spreadsheet-0.6.5.0/lib/spreadsheet.rb:68:in `open'
    from customer_fix_zip.rb:12:in `'

Googling for help didn't... there are only a few posts out there about this situation, but not many responses.

This may be caused by a password on the spreadsheet -- at least that was the cause in my case. Once I had removed the password protection, everything worked just fine.  Hopefully, this will help other folks out there who are experiencing the same problem.