bg
rose1 发表于 2020-08-16 05:14浏览次数：
在类似Unix的操作系统上，bg是作业控制命令。 它在后台恢复挂起的作业，并在作业运行时将用户返回到Shell提示符。
要使外壳符合POSIX标准，必须存在bg。
本文档介绍了bg的bash内置实现。
On Unix-like operating systems, bg is a job control command. It resumes suspended jobs in the background, returning the user to the shell prompt while the job runs.
The presence of bg is required for a shell to comply with the POSIX standard.
This document covers the bash built-in implementation of bg.
目录：
1 bg 运行系统环境
2 bg 语法
3 bg 例子
bg 运行系统环境
bg 语法
bg [job]
选件
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工作
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指定要在后台运行的作业。
作业编号1称为％1，作业编号2称为％2，依此类推；等等。
％，％+或%%表示当前作业；
％-或-指上一个作业。
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bg [job]
Options
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job
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Specifies the job that you want to run in the background.
Job number 1 is referred to as %1, job number 2 is referred to as %2, etc.;
%, %+, or %% refers to the current job;
%- or - refers to the previous job.
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bg 例子
在此示例中，假设我们在bash shell中。
如果您在命令行中启动进程，并且想要在程序完成执行其他操作之前返回到命令行提示符（例如，检查邮件，编辑文本文件等），则可以按Control-Z然后工作就会停止。
如果然后运行命令：
bg %1
停止的作业将恢复操作，但仍保留在后台。它在后台时不会从终端接收任何输入，但是它将继续运行，您可以从命令行继续使用该Shell。
In this example, let's assume we are in the bash shell.
If you initiate a process at the command line, and you want to return to the command line prompt before the program is finished executing to do something else (e.g., check your mail, edit a text file, whatever) you can press Control-Z and the job will stop.
If you then run the command:
bg %1
The stopped job will resume operation, but remain in the background. It will not receive any input from the terminal while it's in the background, but it will keep running, and you can continue to use the shell from the command line.