1. Create informix user and group 

groupadd informix
adduser -g informix informix

2. Edit root's .bash_profile with the following

INFORMIXDIR=/opt/IBM/informix ; export INFORMIXDIR
INFORMIXSERVER=demo_on ; export  INFORMIXSERVER
export PATH=$INFORMIXDIR/bin:$PATH

INFORMIXSERVER: Name of the IDS server.

3. Installing IDS server
InstallMedia/SERVER/installserver 

To do the silent and unattended installation run,
./installserver -silent -acceptlicense=yes

4. edit "onconfig.std" in $INFORMIXDIR/etc

DBSERVERNAME demo_on (this should be the same as INFORMIXSERVER)

5. Copy sqlhosts.std to sqlhosts, chown informix:informix sqlhosts

6. touch $INFORMIXDIR/tmp/demo_on.rootdbs (this is where demo db stores it data)
chown informix:informix $INFORMIXDIR/tmp/demo_on.rootdbs
chmod 660 $INFORMIXDIR/tmp/demo_on.rootdbs

7. Finally initialize and start the IDS 
oninit -iv

8. Check IDS is running

onstat -

The output will show something like this if IDS is running

IBM Informix Dynamic Server Version 11.50.UC3E -- On-Line -- Up 00:22:16 -- 144676 Kbytes

== Debugging ==

In case of any error looking into $INFORMIXDIR/tmp/online.log

9. Installing the demoonstration database.

$ dbaccessdemo
$ dbaccess stores_demo

If the installation was successful, the dbaccessdemo script interacts with the
database server to create and populate the demonstration database, called
stores_demo in this example.

== Debugging ==

In case of any error looking into $INFORMIXDIR/tmp/log.txt And $INFORMIXDIR/tmp/online.log

== Set required environment variables ===
        Set $INFORMIXDIR to the directory where the IDS server is installed.
        Set $PATH to include $INFORMIXDIR/bin                               
        Set $INFORMIXSERVER to the name of the database server              
        Set $ONCONFIG to the name of the active onconfig configuration file.
        If using a sqlhosts file other than $INFORMIXDIR/etc/sqlhosts       
                Set $INFORMIXSQLHOSTS                                       

        If using a locale/language other than the default                   
                Set $CLIENT_LOCALE                                          
                Set $DB_LOCALE                                              
                Set $SERVER_LOCALE                                          
                Set $DBLANG                                                 

Prepare connectivity files                                                  
        sqlhosts                                                            
        /etc/hosts                                                          
        /etc/services                                                       

Prepare configuration file                                                  
        Set DBSERVERNAME                                                    
        Set SERVERNUM                                                       
        Set ROOTNAME                                                        
        Set ROOTPATH
        Set ROOTSIZE


== Uninstall IDS ==

1. First extract JRE from install media , eg, 

mkdir /tmp/jav ; cd /tmp/jav 

/InstallMedia/.jvm.bin (this will extract JRE in current directory)

To uninstall, change to $INFORMIXDIR

./uninstallserver -javahome /tmp/jav/