Ingres is a mature, high-performance relational database solution. It offers scalability, integration and flexibility to leverage information resources across a wide range of platforms, including Linux. Reliable and cost effective, it supports mission-critical applications in small to medium-size businesses and high-volume deployments in large scale enterprises.
You can convert the RPMs to .debs with ?alien.
Installation
Step 1
Download the following files from CA site: http://opensource.ca.com/projects/ingres/
ingres-3.0.2-105-pc-linux-i386.tgz ingresr3documentation.tar.gz
You will need to register with CA first.
Step 2
Prepare for the installation: create 'infrastructure' and unpack the tarballs.
# mkdir -p ingres/documentation
Unpack the documentation. I chose to separate the documentation (PDF files) from the installation software.
# cp ./ingresr3documentation.tar.gz ingres/documentation
# (cd ingres/documentation; tar xzvf ingresr3documentation.tar.gz)
Unpack the Ingres 3 software
# cd ingres;
# tar xzvf ingres-3.0.2-105-pc-linux-i386.tgz
# cd ingres-3.0.2-105-pc-linux-i386
Step 3
Perform the installation
Need to run the Licence scripts first, to accept the conditions. The main database installation script won't work until you do this one first. Trust me, I know this from experience 
# ./ingres-CATOSL
Can now run the main Ingres 3 installation script.
# ./*install
INSTALL OUTPUT: Invoking RPM...
INSTALL OUTPUT: Preparing... ################################ [100%]
INSTALL OUTPUT: System user ingres has been created but no password has been set.
INSTALL OUTPUT: Please set the password to enable login for this user.
INSTALL OUTPUT: 1:ca-ingres ################################ [ 6%]
INSTALL OUTPUT: II_INSTALLATION configured as II.
INSTALL OUTPUT: 2:ca-ingres-dbms ################################ [ 12%]
INSTALL OUTPUT: Setting up Ingres Intelligent DBMS, this may take some time...
INSTALL OUTPUT: See /opt/CA/IngresII/ingres/files/install.log for more info.
INSTALL OUTPUT: 3:ca-ingres-net ################################ [ 18%]
INSTALL OUTPUT: Building the password validation program 'ingvalidpw'.
INSTALL OUTPUT: Could not compile ingvalidpw: Using executable from the distribution instead.
INSTALL OUTPUT: Executable successfully installed.
INSTALL OUTPUT: 4:ca-ingres-qr_run ################################ [ 24%]
INSTALL OUTPUT: 5:ca-ingres-abf ################################ [ 29%]
INSTALL OUTPUT: 6:ca-ingres-c2audit ################################ [ 35%]
INSTALL OUTPUT: 7:ca-ingres-das ################################ [ 41%]
INSTALL OUTPUT: 8:ca-ingres-esql ################################ [ 47%]
INSTALL OUTPUT: 9:ca-ingres-ice ################################ [ 53%]
INSTALL OUTPUT: Setting up Ingres Web Deployment Option, this may take some time..
INSTALL OUTPUT: See /opt/CA/IngresII/ingres/files/install.log for more info
INSTALL OUTPUT: ngres release 3 has installed successfully.
INSTALL OUTPUT: The instance will now be started...
INSTALL OUTPUT:
INSTALL OUTPUT: Starting Ingres, instance
So, the following Ingres packages have been installed:
# rpm -qa | grep ingres
ca-ingres-net-3.0.2-105
ca-ingres-das-3.0.2-105
ca-ingres-odbc-3.0.2-105
ca-ingres-tuxedo-3.0.2-105
ca-ingres-CATOSL-3.0.2-105
ca-ingres-dbms-3.0.2-105
ca-ingres-qr_run-3.0.2-105
ca-ingres-c2audit-3.0.2-105
ca-ingres-esql-3.0.2-105
ca-ingres-jdbc-3.0.2-105
ca-ingres-ome-3.0.2-105
ca-ingres-star-3.0.2-105
ca-ingres-vision-3.0.2-105
ca-ingres-3.0.2-105
ca-ingres-abf-3.0.2-105
ca-ingres-ice-3.0.2-105
ca-ingres-rep-3.0.2-105
ca-ingres-documentation-3.0.2-105
Service 'rc' file has been installed:
# ls -l /etc/init.d/ingres* -rwxr-xr-x 1 root root 7187 Oct 20 19:27 /etc/init.d/ingresII
Indeed: the service list in the runlevel 5 lists the following:
Ingres II name server (iigcn) - running
Ingres II recovery server (dmfrcp) - running
Ingres II DBMS server (iidbms) - 1 running
Ingres II Star server (iistar) - 1 running
Ingres II Net server (iigcc) - 1 running
Ingres II Data Access server (iigcd) - 1 running
Ingres II JDBC server (iijdbc) - not active
Ingres II RMCMD process (rmcmd) - running
Ingres II archiver process (dmfacp) - running
And, sure enough, loads of Ingres processes are running:
# ps -ef | grep ingres ingres 25691 1 0 19:34 pts/1 00:00:00
/opt/CA/IngresII/ingres/bin/iigcn II ingres 25805 1 0 19:34 pts/1 00:00:02
/opt/CA/IngresII/ingres/bin/iidbms recovery (dmfrcp) II ingres 25925 1 0 19:34 pts/1 00:00:01
/opt/CA/IngresII/ingres/bin/dmfacp II ingres 25935 1 0 19:34 pts/1 00:00:19
/opt/CA/IngresII/ingres/bin/iidbms dbms (default) II ingres 26079 1 0 19:34 pts/1 00:00:00
/opt/CA/IngresII/ingres/bin/iigcc II gcc ingres 26135 1 0 19:34 pts/1 00:00:00
/opt/CA/IngresII/ingres/bin/iigcd II gcd ingres 26189 1 0 19:34 pts/1 00:00:02
/opt/CA/IngresII/ingres/bin/iistar star (default) II ingres 26270 1 0 19:34 pts/1 00:00:02
/opt/CA/IngresII/ingres/bin/rmcmd II