Bash 4.0.35
Version of implementation Bash of programming language Unix shellA version of Bash implementation.
Examples:
Hello, World! - Unix shell (212):
This example uses dc (Desktop Calculator), which is a popular non-standard tool that allows processing arbitrary-precision numbers. | dc
means that dc has to be applied to the command.
P
command (the last character before | dc) outputs the last element of the stack. The huge number before P
when written in hexadecimal looks as 0x48656C6C6F2C20576F726C64210A; pairs of adjacent digits form ASCII-codes of characters of “Hello, World!”: 0x48 = H, 0x65 = e, 0x6c = l etc. Thus, when printed, this number is processed as a string.
echo 1468369091346906859060166438166794P | dc
Factorial - Unix shell (48):
This example uses recursive factorial definition.
factorial ()
{
local num=$1;
if [ $num = 0 ]; then
echo 1
return ;
fi;
echo $(( $num * $(factorial $(( $num - 1 )) ) ))
}
for ((n = 0; n <= 16; n++))
do
echo "$n! = " $(factorial $(($n)))
done
Fibonacci numbers - Unix shell (213):
a=0
b=1
for (( n=1; $n<=16; n=$n+1 ));
do
a=$(($a + $b))
echo -n "$a, "
b=$(($a - $b))
done
echo "..."
Factorial - Unix shell (214):
This example uses iterative factorial definition.
f=1
for (( n=1; $n<=17; $((n++)) ));
do
echo "$((n-1))! = $f"
f=$((f*n))
done
Quadratic equation - Unix shell (275):
Bash itself can’t process floating-point numbers, so to calculate roots we have to use bc.
read A;
if [ $A = 0 ]; then
echo "Not a quadratic equation.";
exit 0;
fi
read B;
read C;
D=$(( ($B)*($B)-4*($A)*($C) ));
#integer math only!
if [ $D = 0 ]; then
echo -n "x = "
echo -e "scale=3\n-0.5*($B)/($A)" | bc
exit 0;
fi
echo $D
if [ $D -gt 0 ]; then
echo -n "x1 = "
echo -e "scale=3\n0.5*(-($B)+sqrt($D))/($A)" | bc
echo -n "x2 = "
echo -e "scale=3\n0.5*(-($B)-sqrt($D))/($A)" | bc
else
echo -n "x1 = ("
echo -e "scale=3\n-0.5*($B)/($A)" | bc
echo -n ", "
echo -e "scale=3\n0.5*sqrt(-($D))/($A)" | bc
echo ")"
echo -n "x2 = ("
echo -e "scale=3\n-0.5*($B)/($A)" | bc
echo -n ", "
echo -e "scale=3\n-0.5*sqrt(-($D))/($A)" | bc
echo ")"
fi
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