Using Python:
#!/usr/bin/python
import argparse
p = argparse.ArgumentParser()
p.add_argument('-a', type=int, nargs="+")
p.add_argument('-s', type=int)
args = p.parse_args()
a = args.a
target = args.s
print 'Entered array is:', a
print 'Entered sum is:', target
a_sort = sorted(a)
i = 0
j = len(a) -1
out = []
while i target:
j -= 1
print 'Sum:', target, 'Pairs:', out
=======Output from UNIX=========
$ ./test -a 2 8 1 9 3 7 4 -s 11
Entered array is: [2, 8, 1, 9, 3, 7, 4]
Entered sum is: 11
Sum: 11 Pairs: [[2, 9], [3, 8], [4, 7]]