bash -x set -x set +x

cat sc
#!/bin/bash
for i in {1..3}
do let i++
echo $i
done

----------

bash -x sc

+ for i in '{1..3}'

+ let i++

+ echo 2

2

+ for i in '{1..3}'

+ let i++

+ echo 3

3

+ for i in '{1..3}'

+ let i++

+ echo 4

4

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 use the set -x and set +x in the script to enable the -x log- ging feature of the shell just for that part of the script