Read about set -T in the manual. Also, you have an error in your trap
definition. The $1 inside "..." will expand at *definition* time, not when the
trap is executed. See:
dualbus@yaqui ~/t % cat script
echo '
trap "echo $1" DEBUG
' > ./trapcmd
source ./trapcmd first
source ./trapcmd second
dualbus@yaqui ~/t % bash script
first
dualbus@yaqui ~/t % bash -T script
first
first
dualbus@yaqui ~/t % cat script2
echo '
trap "echo \$1" DEBUG
' > ./trapcmd
source ./trapcmd first
source ./trapcmd second
dualbus@yaqui ~/t % bash script2
dualbus@yaqui ~/t % bash -T script2
second
--
Eduardo Bustamante
https://dualbus.me/
