versions to available versions, or vice versa.
For example, the following compares installed versions to available
versions:
$ nix-env -qc
autoconf-2.59 = 2.59
automake-1.9.4 < 1.9.6
f-spot-0.0.10 - ?
firefox-1.0.4 < 1.0.7
...
I.e., there are newer versions available (in the current default Nix
expression) for Automake and Firefox, but not for Autoconf, and
F-Spot is missing altogether.
Conversely, the available versions can be compared to the installed
versions:
$ nix-env -qac
autoconf-2.59 = 2.59
automake-1.9.6 > 1.9.4
bash-3.0 - ?
firefox-1.0.7 > 1.0.4
...
Note that bash is available but no version of it is installed.
If multiple versions are available for comparison, then the highest
is used. E.g., if Subversion 1.2.0 is installed, and Subversion
1.1.4 and 1.2.3 are available, then `nix-env -qc' will print `<
1.2.3', not `> 1.1.4'.
If higher versions are available, the version column is printed in
red (using ANSI escape codes).
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