Benchmarking shell pipelines and the Unix “tools” philosophy

Re:Benchmarking shell pipelines and the Unix “tools” philosophy by boyter on Wednesday January 08, 2020 @12:55AM (#21988734)

Can anyone comment why you can only use the verbose flag if you use the full path of time?

    time -v ls

does not work but

    /usr/bin/time -v ls

does? I don't have enough knowledge of either linux applications or bash to know whats happening to cause this.

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Re:Benchmarking shell pipelines and the Unix “tools” philosophy by dtwwtd on Wednesday January 08, 2020 @01:03AM (#21988768)

This is very likely because without the full path your shell is using the `time` builtin function of your shell as opposed to using the binary.

The shell's builtin keyword for `time` is more limited in nature than the full `time` binary. This is true of a number of other common unix commands as well, e.g. `echo`. The manpage for your shell should describe the builtins functions.

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Re:Benchmarking shell pipelines and the Unix “tools” philosophy by eesmith on Wednesday January 08, 2020 @01:01AM (#21988762)

Your shell has a built-in "time" command.

man bash:

    If the time reserved word precedes a pipeline, the elapsed as well
    as user and system time consumed by its execution are reported when
    the pipeline terminates.

man time:

     Some shells may provide a builtin time command which is similar
     or identical to this utility.  Consult the builtin(1) manual page.

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Re:Benchmarking shell pipelines and the Unix “tools” philosophy by inimino on Wednesday January 08, 2020 @02:05AM (#21989034)

You can also type `type time` to see that time is a builtin. `which` and `hash` may also be interesting.

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Re:Benchmarking shell pipelines and the Unix “tools” philosophy by amypinka on Wednesday January 08, 2020 @01:05AM (#21988775)

The full path calls a GNU tool, the other calls your shell's builtin function.

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Re:Benchmarking shell pipelines and the Unix “tools” philosophy by tuldia on Wednesday January 08, 2020 @02:57AM (#21989314)

You can also use:

  \time -v ls

to skip the builtin version.

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