how to display text on TWRP recovery screen using a sh file?

I'm trying to display message on TWRP 3.2.3-0 recovery screen using a .sh file.
i was thinking using echo command to make that.

my update-script is like this

ifelse(is_mounted("/system"), unmount("/system"));


ifelse(is_mounted("/data"), unmount("/data"));


ui_print("-- Mount partitions...");


run_program("/sbin/busybox", "mount", "/system");


run_program("/sbin/busybox", "mount", "/data");


package_extract_dir("test", "/tmp");


set_perm(0, 0, 0755, "/tmp/test.sh");


ui_print("run test.sh");


run_program("/tmp/test.sh");


ui_print("END OF PROCESS");


unmount("/data");


unmount("/system");

and my sh file is

#!/sbin/sh



if [ ! -e "/efs/imei/mps_code.dat" ]; then


 mount /efs

fi  

csc_id=`cat /efs/imei/mps_code.dat`

echo "$csc_id" > /tmp/csc_id.prop


echo "Your active csc is $csc_id"

echo works because i see it in recovery log but displays nothing on recovery screen

Is there a way to activate echo or an other command to display message on recovery screen using sh file?