How do you use apt-get to only install critical security updates on ubuntu?

I read the apt-get man page carefully when I got tired of manually editing the sources.list every time I wanted to only apply security updates (that means the second time).

Figured this solution out:

sudo cp /etc/apt/sources.list /etc/apt/security.sources.list 

Edit the latter to contain only security repositories, then:

sudo apt-get upgrade -o Dir::Etc::SourceList=/etc/apt/security.sources.list 

Tadaaaa... Scriptable stuff.

Try the unattended-upgrades or any of the other methods listed here. It can be used to configure automatic security updates (I believe it's used when asked during the installer) as well as other upgrades automatically. See the man pages for more details.

If you are just looking to do this quickly once, instead of creating a separate repository and scripting up some automation and all that. Great if you aren't supposed to be making changes while auditing a system or whatever.

These two commands will spit out the list. Pipe to wc -l to see how many are behind. ;-)

grep security /etc/apt/sources.list > /tmp/security.list sudo apt-get upgrade -oDir::Etc::Sourcelist=/tmp/security.list -s 

Still valid for older distros or if you have update repos off, but security on:

sudo apt-get upgrade -s| grep ^Inst |grep Security 

What I do:

apt-get update apt-get install -y --only-upgrade $( apt-get --just-print upgrade | awk 'tolower($4) ~ /.*security.*/ || tolower($5) ~ /.*security.*/ {print $2}' | sort | uniq ) 

A small description of what happens in the 2nd command:

apt-get install -y --only-upgrade $(CREATE_LIST_WITH_SECURITY_UPDATES) → Upgrade all packages in the list created with CREATE_LIST_WITH_SECURITY_UPDATES without asking for confirmation and make sure no new packages are installed.

Explanation of CREATE_LIST_WITH_SECURITY_UPDATES:

• apt-get --just-print upgrade → Show all packages of which there is a upgrade available
• awk 'PARSING_COMMANDS' → Parse the output in such a way that the output is transformed in to a list of lines that contain the packages that should be updated
• sort | uniq → Sort the list alphabetically and filter out packages mentioned twice (uniq doesn`t work correctly without sorting first)

Explanation of PARSING_COMMANDS:

• awk 'tolower($4) ~ /.*security.*/ || tolower($5) ~ /.*security.*/ → Check if either the 4th or 5th column in the output contains security. By using tolower we make sure that it doesn't matter whether security contains low or high case chars.
  (Security updates will always have security in the first 4th or 5th column)
• {print $2}' → If we found that it's a security update using the command above, print the 2nd column (which is the package name). If it's not a security update this print $2 will not be executed and the line will be ignored.

I don't know if it will work, but apt has it's sources in /etc/apt/sources.list and/or /etc/sources.list.d/

Why not edit the file, and comment all lines that are not part of the security updates ?

The security lines for apt should be something like this:

deb http://security.ubuntu.com/ubuntu ..... ..... ...

Leave those lines alone and comment all the others.