I am trying to use 24x7 to schedule a program that
needs to have a certain environment variable set in
order to work correctly. The program runs against
an Oracle database on a server where Terminal Services
are enabled and this causes problems if SESSIONNAME is
not set to blank.

I can run a .bat file:

set SESSIONNAME=
MAKEFILE PA 00001234 >RepSummary.txt

and this works.

How can I do this within a JAL script?

Just run your batch file from the script
If command line parameters need to be calculated, create butch file dynamically like in the following example:

Dim commands, string, "set SESSIONNAME=\r\n"
Dim parameter, string

// calculate parameter (your business logic goes here)
// Set parameter, @T"mm/dd/yyyy"

// finish and write the batch file
ConcatEx commands, "MAKEFILE PA ", parameter, " >RepSummary.txt\r\n", commands
FileSave "c:\\work_dir\\my_batch.bat", commands

// run it
Dim process_id, number
RunAndWait "c:\\work_dir\\my_batch.bat", "", 0, process_id

// if wanted, delete the batch file
FileDelete "c:\\work_dir\\my_batch.bat"

: I am trying to use 24x7 to schedule a program that
: needs to have a certain environment variable set in
: order to work correctly. The program runs against
: an Oracle database on a server where Terminal Services
: are enabled and this causes problems if SESSIONNAME is
: not set to blank.

: I can run a .bat file: set SESSIONNAME=
: MAKEFILE PA 00001234 >RepSummary.txt

: and this works.

: How can I do this within a JAL script?