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尝试设置时间命令的格式时未找到命令

tag-icon • tag-icon command-line bash time-command
尝试设置时间命令的格式时未找到命令

我正在尝试获取运行命令所需的时间，并以特定格式输出：

time -f "%E" ls -l

这与手册页中的示例类似（并且在线手册页）。但是当我运行此命令时，我得到：

-f: command not found

看起来好像时间命令没有将 -f 读取为参数，而是将其读取为我尝试运行的命令。

如何获取特定格式的命令的执行时间？

答案1

这是因为time它是一个 bash 内置命令 - 并且该内置命令不支持您尝试使用的选项。

尝试一下，使用时间的完整路径跳过内置的并使用真实的路径：

/usr/bin/time -f "%E" ls -l

答案2

不幸的是，time既是 bash 关键字，又是 中的程序/usr/bin。如果您指定完整路径，例如time：

/usr/bin/time -f "%E" ls -l

您将获得所期望的输出。

答案3

改变 bash 内置命令的格式时间使用时间格式多变的

TIMEFORMAT
      The  value  of  this parameter is used as a format string specifying how the timing information for pipelines prefixed with the time reserved word should be displayed.  The % character introduces an escape sequence that is expanded to a time value or
      other information.  The escape sequences and their meanings are as follows; the braces denote optional portions.
      %%        A literal %.
      %[p][l]R  The elapsed time in seconds.
      %[p][l]U  The number of CPU seconds spent in user mode.
      %[p][l]S  The number of CPU seconds spent in system mode.
      %P        The CPU percentage, computed as (%U + %S) / %R.

      The optional p is a digit specifying the precision, the number of fractional digits after a decimal point.  A value of 0 causes no decimal point or fraction to be output.  At most three places after the decimal point may be  specified;  values  of  p
      greater than 3 are changed to 3.  If p is not specified, the value 3 is used.

      The optional l specifies a longer format, including minutes, of the form MMmSS.FFs.  The value of p determines whether or not the fraction is included.

      If this variable is not set, bash acts as if it had the value $'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS'.  If the value is null, no timing information is displayed.  A trailing newline is added when the format string is displayed.

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