last=$(echo `history |tail -n2 |head -n1` | sed 's/[0-9]* //') echo "last command is [$last]" case "1" in "1") date last=$(echo `history |tail -n2 |head -n1` | sed 's/[0-9]* //') echo "last command is [$last]" ;; esac 输出: Tue May 24 12:36:04 CEST...
一些 shell,例如 ksh93 或者 Bash>=4.2 可以通过shopt -s lastpipe命令,指明管道中的最后一个命令在当前 shell 中执行。由于篇幅限制,在此就不展开,有兴趣的可以看Bash FAQ #24[12]。 9. if [grep foo myfile] 初学者会错误地认为,[是 if 语法的一部分,正如 C 语言中的 if ()。但是事实并非如此,if...
The exit status of a pipeline is normally the exit status of the last command in the pipeline. The shell will not return a status until all the commands in the pipeline have completed. If you want your pipelines to be considered a failure if any of the commands in the pipeline fail, ...
if [ $? -eq 0 ]; then: Checks the exit status of the previous command. If it's 0 (indicating success), print a success message. Otherwise, it prints a failure message. 9. Write a Bash script that performs a simple arithmetic operation using user input. Code: #!/bin/bash # Ask t...
prometheus_node_exporter.sh - starts Prometheus node_exporter locally, downloading it if not found in $PATH ssh_dump_stats.sh - uses SSH and dump_stats.sh to dump common command outputs from remote servers to a local tarball. Useful for vendor support cases ssh_dump_logs.sh - Uses SSH to...
首先,Shell 是一个程序,提供一个与用户对话的环境。这个环境只有一个命令提示符,让用户从键盘输入命令,所以又称为命令行环境(commandline,简写为 CLI)。Shell 接收到用户输入的命令,将命令送入操作系统执行,并将结果返回给用户。本书中,除非特别指明,Shell 指的就是命令行环境。
Version 3.7.2 2005/11/16 作者:Mendel Cooper mail:thegrendel@theriver.com 这本书假定你没有任何脚本或一般程序的编程知识,但是如果你有相关的知识,那么你将很容易 达到中高级的水平...all the while sneaking in little snippets of UNIX? wisdom and lor... ...
准备工作 手机已经root adb.exe 已经放到了系统环境变量，也就是打开cmd 后输入 adb不会报错，如下图...
如果父进程不通过管道与任何子进程通信，则必须确保尽早关闭管道的两端（例如，在等待之前），以便其子...
If you’re writingbashscripts, you’ll want to be sure to explicitly set return values, so that$?is set properly from your script. If you don’t, the value set will be the value of the last command run, which you may not want as your result. ...