Bdtyktl

I have been trying to figure out a problem with a Ubuntu 16.04 server for a while and recently found that the problem is that php 7.3 seems to have been automatically installed during a "apt-get update ; apt-get -y dist-upgrade" on October 15, 2018 so that the system started to use php 7.3 instead of php 7.1 that was already installed.

On August 2, 2018, I had these php related packages installed according to dpkg -l|grep php|grep -v ^rc (I have a saved output of "dpkg -l" from that date):

libapache2-mod-php7.1  

php-apcu  

php-common  

php7.1  

php7.1-cli  

php7.1-common  

php7.1-curl  

php7.1-gd  

php7.1-intl  

php7.1-json  

php7.1-mbstring  

php7.1-mysql  

php7.1-opcache  

php7.1-readline  

php7.1-soap  

php7.1-xml  

php7.1-xmlrpc  

php7.1-zip  

If I compare with a saved output of dpkg -l from August 2, 2018, and today February 4, 2019, I see that I now have these additionally php packages installed:

libphp7.3-embed  

php7.3-cli  

php7.3-common  

php7.3-json  

php7.3-opcache  

php7.3-readline  

The log from apt-get update ; apt-get -y dist-upgrade on October 15, 2018, looks like this:

[...]  

The following NEW packages will be installed:  

libargon2-0 libpcre2-8-0 libphp7.3-embed libsodium23 php7.3-cli

php7.3-common php7.3-json php7.3-opcache php7.3-readline  

The following packages will be upgraded:  

libapache2-mod-php7.1 php-apcu php7.1 php7.1-cli php7.1-common php7.1-curl

php7.1-gd php7.1-intl php7.1-json php7.1-mbstring php7.1-mysql

php7.1-opcache php7.1-readline php7.1-soap php7.1-xml php7.1-xmlrpc

php7.1-zip python-requests python3-requests  

19 upgraded, 9 newly installed, 0 to remove and 0 not upgraded.  

[...]  

I would like to figure out why those php 7.3 related packages where automatically installed on October 15, 2018. Any idea?

A reverse dependency apt query will tell you which packages depend upon a package. This is the inverse of a normal dependency search.

Example: Package foo depends upon package libfoo1.

$ apt-cache depends foo

foo

  Depends: libfoo1



$ apt-cache rdepends libfoo1

libfoo1

Reverse Depends:

  foo

In 16.04 and newer systems, you can use either apt or apt-cache to do the query. Syntax is identical.

Do a reverse dependency search upon those php7.3 packages to find what pulled them in.