for j in *.bak; do mv -- "$j" "temp_${j%.bak}.txt"; done
Example:
from:
123.bak
456.bak
asd.bak
to:
temp_123.txt
temp_456.txt
temp_ask.txt
for j in *.bak; do mv -- "$j" "temp_${j%.bak}.txt"; done
Example:
from:
123.bak
456.bak
asd.bak
to:
temp_123.txt
temp_456.txt
temp_ask.txt