Thanks Johnson and Cherry for the responses.

The output from

sessList=$(ps -ef | awk -v sq="'" 'NR > 1 { printf sq "%s" sq ",", $2 }' )

looks like -
'0','1','3','4',

There is an additional comma in the end.

The Output from Cherry's command is exactly the one I was looking for.

However, can you please help me understand the syntax (am still grappling with sed and awk using google) so that I can change it if required in the future.