Hi,

Is there any difference between setting an environment variable by EXPORT and by setenv?

export and not EXPORT is used by sh and ksh shells. setenv is used by csh.

The syntax also differs for both.

Can environmental variables exported using export and setenv be accessible across different terminals?
Also do they persist for accessing via programs using "getenv()" call ?

No there isn't a shared realtime environment in multiple shell sessions.

Typically you would setup some sort of profile to kick start the environment that is full of the variables (~/.profile, ~/.bashrc, ~/.tcshrc, etc) just like as well as employ the system wide equivalent /etc/profile and what not.

But not there isnt a: super_export TERM=vt100 that will force that variable to be inherited by all your running shells immediately.

The export and setenv calls typically are used for other programs or sub programs to use and shouldn't be confused with the 'set' variables in some shell scripts that are local for that shell sessions. Or that programs will set for themselves and their sub programs but will disappear when the program ends.