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I'm trying to set up an apt-mirror service for an offline repository but I've hit a weird error. I edited my mirror.list file to contain the proper paths (a USB drive mounted at /media/Ubuntu) but when I try to run apt-mirror, I get the following:

$ sudo apt-mirror /etc/apt/mirror.list
Argument "M-BM- " isn't numeric in numeric lt (<) at /usr/bin/apt-mirror line 204.
Downloading 982 index files using   threads...
Illegal division by zero at /usr/bin/apt-mirror line 209.

Any ideas as to what this could mean?

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closed as off-topic by Eliah Kagan, txwikinger, minerz029, karel, Eric Carvalho Jan 18 '14 at 0:58

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Bug reports and problems specific to development version of Ubuntu should be reported on Launchpad so that developers can see, track and fix these issues." – Eliah Kagan, txwikinger, minerz029, karel, Eric Carvalho
If this question can be reworded to fit the rules in the help center, please edit the question.

Though this has been answered beautifully, it is still a bug for apt-mirror to crash with a division by zero error when a configuration file is malformed. I highly recommend reporting this as a bug; Gilles' analysis should help and the information from it can be included in the bug report to assist triagers and developers. – Eliah Kagan Jan 17 '14 at 8:18
up vote 9 down vote accepted

I'm looking at my crystal ball… It's a bit hazy… Ah, there it is.

You have an unbreakable space after nthreads in your mirror.list file. Replace it by a normal space.

Explanation: line 204 in the script is where apt-mirror compares the number of URLS — which is always numeric — with the value of the nthreads configuration setting. The parser for configuration settings doesn't check for numeric values, so a non-numeric value isn't detected until the setting is used. M-BM- displays two unprintable bytes c2a0 (0x42=B and 0x20=space, with M- indicating +0x80); this two-byte sequence encodes the unbreakable space in UTF-8.

In the future, post the full content of your configuration file when you ask such questions.

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This deserves many upvotes. It's a very neat explanation, shows what's going on and is therefore very interesting out of a simple cause for an issue! – gertvdijk Jan 15 '13 at 21:43

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