Sort lines by field, using index and "number"/"string" compare.

sort_lines_by_field.rb

all_line_objs = Array.new()

FIELD_SPLITTER = ' ' #change to '\t', ',', ':' as you need;
FIELD_INDEX = 1 #Start from 0;
FIELD_TYPE = "number" #number or string;

File.open(ARGV[0]).each { |line|
    fields = line.strip.split(FIELD_SPLITTER)
    field  = fields[FIELD_INDEX]
    line_obj = {field:field, line:line.strip}
    all_line_objs.push line_obj
}

all_line_objs.sort {|a, b|
    if FIELD_TYPE == "number" then
        b[:field].to_f <=> a[:field].to_f #reverse;
    else
        a[:field] <=> b[:field]
    end
}.each {|line_obj|
    puts line_obj[:line]
}

if ARGV[0] is nil, should i use stdin? this can assit Pipe cmd_a ... | cmd_b ... | ... syntax under Linux