[takluyver]

'Manually' probably means not using a package manager - either with the configure/make dance, or with a binary installer like Google Earth used for a long time. In those cases, you still need to sort out dependencies manually.

[keithpeter]

Yup

   apt-get install <something-in-repository-or-ppa-you-added>

will bring down all the dependencies needed. That's the reason they package stuff against release numbers, so the dependencies are all consistent.

    dpkg -i <some-random-deb-you-downloaded>

may give dependency errors.

[andyking]

I get dependency errors on Chrome under Ubuntu 12.04, when I do a dpkg -i google-chrome-stable-whatever.deb.

But a quick apt-get -f install after I get those errors sorts it out.

[keithpeter]

Absolutely; if the dependencies exist within the appropriate Ubuntu repositories, or the ppas you have active, then the needed libraries can be installed.

Random downloading of debs from Web sites could lead to a situation where a different version of a dependency is needed. "foo needs libnaff-ubuntu345 but libnaff-ubuntu345 is not going to be installed" type errors result.

[mhall119]

If you open the .deb in Software Center, it'll take care of the dependencies for you at the same time.

[gcr]

On the command line, you can use (ubuntu-specific) `gdebi <packagename>.deb` to automate that process for you.