# column.rb
# extract a column from a multi column file
#
 
if (ARGV.empty?) then
        STDERR.puts "Need filename"
        exit
end
 
# note first argument must be filename, second must be column
fileName = ARGV[0]
columnStr = ARGV[1]
puts "Filename = #{fileName} Column = #{columnStr}"
 
if (FileTest.exists?(fileName)) then
        lineNum = 1
        fin = File.open(fileName)
        fin.each_line { |line|
                elements = line.split(/ /)
                if (elements.size < columnStr.to_i) then
                        STDERR.puts "#{lineNum} does not have #{columnStr} colum
ns"
                else
                        colNum = columnStr.to_i - 1
                        puts elements[colNum]
                end
                lineNum = lineNum.succ
        }
        fin.close
end

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