Conditionals in Bash
If statements
- Conditional blocks start with
if and end with the inversion fi (this is a common syntactic pattern in bash)
- The conditional expression must be placed in square brackets with spaces either side. The spaces matter: if you omit them, the code will not run
- We designate the code to run when the conditional is met with
then
- We can incorporate else if logic with
elif
Basic example
if [ -e $var ]; then
# Do something
else
# Do something else
fi
If, else
if [ "$myMove" -eq "$opponentMove" ]; then
(( totalScore+=myMove+3 ))
elif [ $absDiff -eq 2 ] && [ "$myMove" -gt "$opponentMove" ]; then
(( totalScore+=myMove))
elif [ $absDiff -eq 2 ] && [ "$opponentMove" -gt "$myMove" ]; then
(( totalScore+=myMove+6))
elif [ $absDiff -eq 1 ] && [ "$opponentMove" -gt "$myMove" ]; then
(( totalScore+=myMove))
elif [ $absDiff -eq 1 ] && [ "$myMove" -gt "$opponentMove" ]; then
(( totalScore+=myMove+6))
fi
Nested conditionals
if [[ "$line" =~ ^$ ]]; then
if [[ "$runningTotal" -gt "$highest" ]]; then
(( highest=runningTotal ))
fi
# Reset running sum
(( runningTotal=0 ))
fi
