在ruby腳本中調用命令

Question

有沒有辦法在ruby腳本中調用像last這樣的命令？我可以使用%x在腳本中調用諸如ls和ls -l之類的命令，但是對於由最後一個命令提供的複雜且不斷擴展的日誌信息，這可以接受嗎？

Answer 1

下面是一個例子，來獲取用戶名，IP，啓動和持續時間：

%x(last -i).each_line do |line| 
    line.chomp!        # Removes newline 
    break if line.empty?     # last is done 

    # 3 possibilities to extract information : 
    user, *other_columns = line.split(' ') # 1. Use split 
    start = Time.parse(line[39,16])   # 2. Use known position of a column 
    ip = line[22,17].strip 
    if line =~/\((\d+):(\d+)\)/    # 3. Use a regex 
    duration = $1.to_i*60+$2.to_i 
    else 
    duration = nil 
    end 

    info={user: user, ip: ip, start: start, duration: duration} 
    #TODO: Check that user isn't "reboot" 
    puts info 
end 


# {:user=>"ricou", :ip=>"0.0.0.0", :start=>2016-11-01 21:29:00 +0100, :duration=>141} 
# {:user=>"ricou", :ip=>"0.0.0.0", :start=>2016-11-01 15:21:00 +0100, :duration=>57} 

哪些信息你需要什麼呢？