Using apt-get to update packages

Get the latest package lists:

$apt-get update

Check the versions:

$ apt-cache policy bash
bash:
  Installed: 4.2+dfsg-0.1
  Candidate: 4.2+dfsg-0.1+deb7u3
  Version table:
     4.2+dfsg-0.1+deb7u3 0
        500 http://mirrordirector.raspbian.org/raspbian/ wheezy/main armhf Packages
 *** 4.2+dfsg-0.1 0
        100 /var/lib/dpkg/status
$ 

Install the update:

$ sudo apt-get install bash
...
The following packages will be upgraded:
  bash
1 upgraded, 0 newly installed, 0 to remove and 206 not upgraded.
Need to get 1,443 kB of archives.
...
$