shell命令的打印执行时间 [英] Print execution time of a shell command

问题描述

可以使用以下组合打印shell命令的执行时间？

Is is possible to print the execution time of a shell command with following combination?

root@hostname:~# "command to execute" && echo "execution time"

推荐答案

是bash的内置时间（当你执行时间命令时应该默认调用）和 / usr / bin / time （这应该要求您通过完整路径调用它）。

Don't forget that there is a difference between bash's builtin time (which should be called by default when you do time command) and /usr/bin/time (which should require you to call it by its full path).

$ c> time 始终打印到stderr，但 / usr / bin / time 将允许您将时间输出发送到特定文件，不要干扰执行的命令的stderr流。此外， / usr / bin / time 的格式可在命令行或上通过环境变量 TIME 配置的 仅支持 >环境变量。

The builtin time always prints to stderr, but /usr/bin/time will allow you to send time's output to a specific file, so you do not interfere with the executed command's stderr stream. Also, /usr/bin/time's format is configurable on the command line or by the environment variable TIME, whereas bash's builtin time format is only configured by the TIMEFORMAT environment variable.

$ time factor 1234567889234567891 # builtin
1234567889234567891: 142662263 8653780357

real    0m3.194s
user    0m1.596s
sys 0m0.004s
$ /usr/bin/time factor 1234567889234567891
1234567889234567891: 142662263 8653780357
1.54user 0.00system 0:02.69elapsed 57%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+215minor)pagefaults 0swaps
$ /usr/bin/time -o timed factor 1234567889234567891 # log to file `timed`
1234567889234567891: 142662263 8653780357
$ cat timed
1.56user 0.02system 0:02.49elapsed 63%CPU (0avgtext+0avgdata 0maxresident)k
0inputs+0outputs (0major+217minor)pagefaults 0swaps

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