jida...@jidanni.org wrote:
> Is there any case where
> $ cd /var/cache/apt/archives
> $ set -- $(ls -r some_package_*)
> $ dpkg --compare-versions $1 gt $2
> isn't true?
Yes.
* dpkg --compare-versions uses ASCII to compare letters (so B < a).
In non-C locales, ls does not.
* dpkg --compare-versions treats ~ specially (so
git-core_1%3a1.6.6~rc-1_i386.deb < git-core_1%3a1.6.6-1_i386.deb).
Even in the C locale, ls does not.
* dpkg --compare-versions compares the numeric part of a version
numerically (so 1.2 < 1.11).
ls does not.
On the other hand, 'ls -v' behaves like dpkg --compare-versions in
the respects described above. But:
* dpkg --compare-versions treats : specially (so 3 < 1:1).
ls -v does not.
'ls -v' and 'dpkg --compare-versions' differ in plenty of other ways,
too.
To handle epochs correctly, you really need to be unescaping the
version number part of the filename. If your application permits the
slowdown, I think it would be simpler to use
show_version() {
dpkg-deb --showformat='${Version}' --show "$1"
}
dpkg --compare-versions $(show_version "$1") gt $(show_version "$2")
See <http://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version>,
<http://www.gnu.org/software/coreutils/manual/coreutils.html#Details-about-version-sort>.
Hope that helps,
Jonathan
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