2016-01-22 16:47

PHP exec()和运行shell脚本给出了不同的结果


I have that sends a request to some URL and prints the execution time using whet. Here is the source code:

time wget http://some.url

When I run it from command line, I see time result with an accuracy of 3 decimal places:

real    0m0.584s
user    0m0.000s
sys     0m0.002s

But, when I run this SH using PHP function exec("", $output) - , I see time result with an accuracy of only 2 decimal places:

0.00user 0.00system 0:00.32elapsed 0%CPU (0avgtext+0avgdata 3788maxresident)k

How can I get the same result, as I do see in command line?

  • 点赞
  • 写回答
  • 关注问题
  • 收藏
  • 复制链接分享
  • 邀请回答


  • drgovyk64676 drgovyk64676 5年前

    The answer is in the manual:

    Note: some shells (e.g., bash(1)) have a built-in time command that provides less functionality than the command described here. To access the real command, you may need to specify its pathname (something like /usr/bin/time).

    You're getting the increased precision from the bash builtin; if you run /usr/bin/time from the shell you will see two decimal places as well.

    Unfortunately, time is a special case, in that it's a keyword and not actually a builtin command. Otherwise bash's builtin command could be used to force it.

    So it looks like you're stuck with two decimal places unless you want to try a different method:

    start_time=`date +%s%N`
    wget http://some.url
    end_time=`date +%s%N`
    bc -l <<< "scale=4;($end_time - $start_time) / 1000000000"
    点赞 评论 复制链接分享