bash bash脚本在文件中写入执行时间
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bash script write executing time in a file
提问by NikM
I need to write the time taken to execute this command in a txt file:
我需要在 txt 文件中写入执行此命令所需的时间：
time ./program.exe
How can I do in bash script?
我该怎么做 bash 脚本？
I try with >> time.txtbut that doesn't work (the output does not go to file and does go to the screen).
我尝试过，>> time.txt但这不起作用（输出不会进入文件并且会进入屏幕）。
回答by Jonathan Leffler
Getting timein bashto write to a file is hard work. It is a bashbuilt-in command. (On Mac OS X, there's an external command, /usr/bin/time, that does a similar job but with a different output format and less recalcitrance.)
入门time中bash写入一个文件是艰苦的工作。它是一个bash内置命令。（在 Mac OS X 上，有一个外部命令 ，/usr/bin/time可以完成类似的工作，但具有不同的输出格式和更少的顽固性。）
You need to use:
您需要使用：
(time ./program.exe) 2> time.txt
It writes to standard error (hence the 2>notation). However, if you don't use the sub-shell (the parentheses), it doesn't work; the output still comes to the screen.
它写入标准错误（因此是2>符号）。但是，如果不使用子外壳（括号），则不起作用；输出仍然出现在屏幕上。
Alternatively, and without a sub-shell, you can use:
或者，如果没有子外壳，您可以使用：
{ time ./program.exe; } 2> time.txt
Note the space after the open brace and the semi-colon; both are necessary on a single line. The braces must appear where a command could appear, and must be standalone symbols. (If you struggle hard enough, you'll come up with ...;}|somethingor ...;}2>&1. Both of these identify the brace as a standalone symbol, though. If you try ...;}xyz, the shell will (probably) fail to find a command called }xyz, though.)
注意大括号和分号后面的空格；两者都需要在一行中。大括号必须出现在命令可能出现的地方，并且必须是独立的符号。（如果你足够努力，你会想出...;}|somethingor ...;}2>&1。不过，这两个都将大括号识别为一个独立的符号。不过，如果你尝试...;}xyz，shell 将（可能）找不到名为 的命令}xyz。）
I need to run more command in more terminal. If I do this:
xterm -xrm '*hold: true' -e (time ./Program.exe) >> time.exe & sleep 2it doesn't work and tells me
Syntax error: "(" unexpected. How do I fix this?
我需要在更多终端中运行更多命令。如果我这样做：
xterm -xrm '*hold: true' -e (time ./Program.exe) >> time.exe & sleep 2它不起作用并告诉我
Syntax error: "(" unexpected。我该如何解决？
You would need to do something like:
您需要执行以下操作：
xterm -xrm '*hold: true' -e sh -c "(time ./Program.exe) 2> time.txt & sleep 2"
The key change is to run the shell with the script coming from the argument to the -coption; you can replace shwith /bin/bashor an equivalent name. That should get around any 'Syntax error' issues. I'm not quite sure what triggers that error, though, so there may be a simpler and better way to deal with it. It's also conceivable that xterm's -eoption only takes a single string argument, in which case, I suppose you'd use:
关键的变化是使用来自参数到-c选项的脚本运行 shell ；您可以替换sh为/bin/bash或等效名称。这应该可以解决任何“语法错误”问题。不过，我不太确定是什么触发了该错误，因此可能有一种更简单更好的方法来处理它。也可以想象xterm's-e选项只接受一个字符串参数，在这种情况下，我想你会使用：
xterm -xrm '*hold: true' -e 'sh -c "(time ./Program.exe) 2> time.txt & sleep 2"'
You can manual bash xtermas well as I can.
你可以xterm和我一样手动 bash 。
I'm not sure why you run the timed program in background mode, but that's your problem, not mine. Similarly, the sleep 2is not obviously necessary if the hold: truekeeps the terminal open.
我不知道你为什么在后台模式下运行定时程序，但那是你的问题，不是我的。同样，sleep 2如果hold: true使终端保持打开状态，则显然没有必要。
回答by hmakholm left over Monica
It's not easy to redirect the output of the bash builtin time.
重定向 bash builtin 的输出并不容易time。
One solution is to use the external timeprogram:
一种解决方案是使用外部time程序：
/bin/time --append -o time.txt ./program.exe
(on most systems it's a GNU program, so use info timerather than manto get its documentation).
（在大多数系统上，它是一个 GNU 程序，因此使用info time而不是man获取其文档）。
回答by BIBS
time_elapsed=(time sh -c "./program.exe") 2>&1 | grep "real" | awk '{print $(NF)}'echo time_elapsed > file.txt
This command should give you the exact time consumed in bash in a desired file..
time_elapsed= (time sh -c "./program.exe") 2>&1 | grep "real" | awk '{print $(NF)}'echo time_elapsed > file.txt 此命令应该为您提供所需文件中 bash 消耗的确切时间。
You can also redirect this to a file usng 2 > file.txt as explained in another reply.
您还可以将其重定向到文件 usng 2 > file.txt，如另一个回复中所述。
回答by BIBS
Just enclose the command to time in a { .. }:
只需将命令括在时间中{ .. }：
{ time ./program.exe; } 2>&1
Of course, the output of builtin time goes to stderr, thus the needed redirection 2>&1.
当然，内置时间的输出进入 stderr，因此需要重定向2>&1。
Then, it may appear to be tricky to capture the output, let's use a second { .. }to read the command more easily, this works:
然后，捕获输出似乎很棘手，让我们用一秒钟{ .. }来更轻松地读取命令，这是有效的：
{ { time ./program.exe; } 2>&1; } >> time.txt # This works.
However, the correct construct should simply have the capture reversed, as this:
但是，正确的构造应该简单地反转捕获，如下所示：
{ time ./program.exe; } >> time.txt 2>&1; # Correct.
To close any possible output from the command, redirect it's output to /dev/null, as this:
要关闭命令的任何可能输出，请将其输出重定向到 /dev/null，如下所示：
{ time ./program.exe >/dev/null 2>&1; } >> time.txt 2>&1 # Better.
And, as now there is only output on stderr, we could simply capture just it:
而且，由于现在只有 stderr 输出，我们可以简单地捕获它：
{ time ./program.exe >/dev/null 2>&1; } 2>> time.txt # Best.
The output from ./program should be redirected, or it may well end inside time.txt.
./program 的输出应该被重定向，否则它可能会在 time.txt 中结束。
