Conditional structures
If-then-else and elif
if [ $a -eq $b ]; then
echo "a is equal to b"
fi
if [ $a -eq $b ]; then
echo "a is equal to b"
else
echo "a is not equal to b"
fi
if [ $a -eq $b ]; then
echo "a is equal to b"
elif [ $a -eq $c ]; then
echo "a is not equal to b"
else
echo "a is not equal to b or c"
fi
Test Operators
if [ -f filename ]; then
echo "file exists"
fi
if [ -d dirname ]; then
echo "directory exists"
fi
if [ ! -d dirname ]; then
mkdir dirname
fi
Case
case $a in
1) echo "a is 1" ;;
2) echo "a is 2" ;;
3) echo "a is 3" ;;
*) echo "a is not 1, 2 or 3" ;;
esac