To find out the RAM size (memory) on an AIX system from the command line, you can use the lsattr command with the -El mem0 parameter.
For example, to display the RAM size of your system, you can use the following command:
lsattr -El mem0 | awk '{print $2}'
This will display the RAM size in megabytes.
You can also use the svmon command to display the memory usage and capacity of your system. For example:
svmon -G
This will display the memory usage and capacity of your system, including the total RAM size and the amount of free and used memory.
You can find more information about the lsattr and svmon commands and their options in the AIX documentation or by running the lsattr --help and svmon --help commands.