#!/bin/sh
# Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)
#
# This work is licensed under the Creative Commons Attribution-NonCommercial-
# ShareAlike License. To view a copy of this license, visit 
# http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
# Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
# 94105, USA.

function selection_sort {
  local entries_ref=$1
  local i j min_idx min_val entries_N
  
  eval entries_N=\${#$entries_ref[@]}
  for i in `seq 0 $[entries_N-1]`; do 
    # find minimum value in the range i..(number_of_entries-1) 
    min_idx=$i
    eval min_val=\${$entries_ref[$min_idx]}
    for j in `seq $[i+1] $[entries_N-1]`; do
      eval val_j=\${$entries_ref[$j]}
      if [ `bc<<<"$val_j < $min_val"` -eq 1 ]; then
        min_idx=$j
        min_val=$val_j
      fi
    done
    # if needed, swap the $i-th entry with the $min_idx entry
    if [ $min_idx -ne $i ]; then
       eval $entries_ref[$min_idx]=\${$entries_ref[$i]}
       eval $entries_ref[$i]=$min_val
    fi
  done
}

if [ $# -ne 1 ]; then
  echo -e "Usage:\n\t$0 (file with numbers to sort)\n"; exit -1
fi

# read in the entries
file_name=$1
exec 3<$file_name
while read -u 3 inline; do entries[${#entries[@]}]=$inline; done 
3>&-

# sort them
selection_sort entries

# display the results
for entry in ${entries[@]}; do echo $entry; done