时间命令的非法选项

Question

I am having some issues with the time command time . It works fine but since time gives 3 numbers in output(real, user and sys) I was looking on how to get only the user time. I found many posts that say to use /usr/bin/time -f "%U" but I get this errors :

/usr/bin/time: illegal option -- f
usage: time [-lp] command.

I also can't find the option -f when I type man time

I tried to skip it and write: /usr/bin/time "%U" and I get %U: No such file or directory

I have installed GNU-time but nothing changed. what is the issue?

Answer 1

There are several time commands...

---

If you run:

type time

and get:

time is a shell keyword

that means you are using bash 's built-in shell command that does not accept the option you want. The help for this command, like all shell built-ins, is available using:

help time

---

If you run:

type time

and get:

time is hashed (/usr/bin/time)

that means you are using the Apple-supplied (BSD-like) time command that does not accept the option you want. That is also the one described in the man-pages.

---

If you installed gnu-time with homebrew , you need to run:

gtime

unless you didn't set your PATH to include /usr/local/bin like you should if you use homebrew , in which case you would need to run:

/usr/local/bin/gtime

and view the man-page with:

man gtime

If you want to always use the command time in place of gtime , and I would not recommend this, you need to run:

brew info gnu-time

and read what it says about setting:

PATH="/usr/local/opt/gnu-time/libexec/gnubin:$PATH"