nice
秃噜豆儿 发表于 2020-07-23 15:51浏览次数：
在Unix-like的操作系统上，nice命令以修改的调度优先级运行命令。
本文介绍nice的GNU/Linux版本。
On Unix-like operating systems, the nice command runs a command with a modified scheduling priority.
This document covers the GNU/Linux version of nice.
目录：
1 nice 运行系统环境
2 nice 描述
3 nice 语法
4 nice 选项
5 nice 示例
nice 运行系统环境
nice 描述
nice使用调整后的“niceness”运行命令命令，这会影响进程调度。精度值较低的进程将获得更高的优先级和更多的CPU时间。具有较高niceness值的进程（“更好的”进程）将被赋予更低的优先级和更少的CPU时间，从而为要求更高的进程释放资源。
精确性值的范围为-20（对过程最有利）到19（对过程最不利）。
如果没有命令，nice将打印当前niceness级别。
nice runs command COMMAND with an adjusted "niceness", which affects process scheduling. A process with a lower niceness value is given higher priority and more CPU time. A process with a higher niceness value (a "nicer" process) is given a lower priority and less CPU time, freeing up resources for processes that are more demanding.
Niceness values range from -20 (most favorable to the process) to 19 (least favorable to the process).
With no COMMAND, nice prints the current niceness level.
nice 语法
nice [OPTION] [COMMAND[ARG]...]
nice [OPTION] [COMMAND[ARG]...]
nice 选项
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-nN, --adjustment=N
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将整数N加到niceness上（默认值为10）。
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--help
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显示帮助消息并退出。
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--version
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输出版本信息并退出。
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-nN, --adjustment=N
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Add integer N to the niceness (default is 10).
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--help
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Display a help message and exit.
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--version
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Output version information and exit.
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nice 示例
nice
显示新进程的默认niceness级别；通常为零，因此输出可能如下所示：
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nice -n13 pico myfile.txt
在上运行pico命令我的文件.txt精确增量为13。因为我们已经看到默认的niceness级别是0，所以运行pico时niceness级别为0加13，即13。因此，pico将能够使用比任何运行在niceness级别大于14的进程更高的CPU资源，但是它的优先级低于值小于14的进程。
实际上，这告诉系统将pico视为低优先级进程，而不是最低优先级进程。
nice
Displays the default niceness level of new processes; this is commonly zero, so the output would probably look like this:
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nice -n13 pico myfile.txt
Runs the pico command on myfile.txt with an niceness increment of 13. Since we already saw that the default niceness level was zero, this runs pico with a niceness level of zero plus 13, which is 13. As a result, pico will be able to use CPU resources with a higher priority than any process running with a niceness level greater than 14, but will have a lower priority than processes with a value less than 14.
Effectively, this tells the system to treat pico as a low-priority process, but not the lowest.