hypotenuse.sh

Shall高级编程

#!/bin/bash
# hypotenuse.sh: Returns the "hypotenuse" of a right triangle.
#                (square root of sum of squares of the "legs")

ARGS=2                # Script needs sides of triangle passed.
E_BADARGS=65          # Wrong number of arguments.

if [ $# -ne "$ARGS" ] # Test number of arguments to script.
then
  echo "Usage: `basename $0` side_1 side_2"
  exit $E_BADARGS
fi


AWKSCRIPT=' { printf( "%3.7f\n", sqrt($1*$1 + $2*$2) ) } '
#             command(s) / parameters passed to awk


# Now, pipe the parameters to awk.
    echo -n "Hypotenuse of $1 and $2 = "
    echo $1 $2 | awk "$AWKSCRIPT"
#   ^^^^^^^^^^^^
# An echo-and-pipe is an easy way of passing shell parameters to awk.

exit 0

# Exercise: Rewrite this script using 'bc' rather than awk.
#           Which method is more intuitive?