如何让 bash 默认使用时间二进制文件 (/usr/bin/time) 而不是 shell 关键字？
which time返回/usr/bin/time
type time返回time is a shell keyword
运行time显然是在执行shell关键字：
$ time
real 0m0.000s
user 0m0.000s
sys 0m0.000s
$ /usr/bin/time
Usage: /usr/bin/time [-apvV] [-f format] [-o file] [--append] [--verbose]
[--portability] [--format=format] [--output=file] [--version]
[--quiet] [--help] command [arg...]
enable -n time 返回 bash: enable: time: not a shell builtin