(If n is omitted, the exit status is that of the last command executed. ) 格式:$? 上一个命令的退出码。 格式:trap "commands" EXIT 退出时执行commands指定的命令。( A trap on EXIT is executed before the shell terminates.) 退出码(exit status,或exit code)的约定: 0表示成功(Zero - Success...
When you execute a command or run a script, you receive anexit code. An exit code is a system response that reports success, an error, or another condition that provides a clue about what caused an unexpected result from your command or script. Yet, you might never know about the code,...
date last=$(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 [$last]" ;; esac 输出: Tue May 24 12:36:04...
When you execute a command or run a script, you receive anexit code. An exit code is a system response that reports success, an error, or another condition that provides a clue about what caused an unexpected result from your command or script. Yet, you might never know about the code,...
seq Displays an incremental sequence of numbers from first to last. service This command is used to manage system services. set Used to manipulate shell variables and functions. setfdprm Sets floppy disk parameters as provided by the user. setkeycodes Load kernel scancode-to-keycode mapping table...
When the original PROMPT_COMMAND is an array: exit code of last executed command is not restored before executing the commands stored inside the original PROMPT_COMMAND array __vsc_status is assigned the exit code of the penultimate command stored inside the original PROMPT_COMMAND array Those 2...
!command#执行最近的这个命令(使用原来的选项和参数执行) !!#执行上一个命令 五、Bash shell的操作环境 5.1命令环境:由PATH变量提供的文件路径的外部命令、bash自身內置命令builtin、历史命令,由于alias来实现內置命令和外部命令的查找及历史命令机制来实现。
注意,su 不指定用户名称时,默认会切换到超级用户,即root。 如果不进入用户的登录shell交互式执行命令,还可以直接 -c “command”的方式执行命令,即:[wind@bogon shellscript]$ su - -c "ls" Password: anaconda-ks.cfg initial-setup-ks.cfg [wind@bogon shellscript]$ 退出shell的方式,exit或者ctrl-d均可...
$!" # 返回最近一个后台命令的进程 ID sleep 1 echo "the last parameter of the previous command: \$_ $_" # 上一个命令的最后一个参数, 比如这里是1 选项参数传递 getopts 是一个用于解析命令行选项和参数的内置命令, 语法为 getopts optstring name optstring 是一个字符串, 定义脚本可以接收的选项, ...
Code: #!/bin/bash echo "Hello, world!" Output: ad@DESKTOP-3KE0KU4:~$ ./test1.sh Hello, world! Explanation: In the exercise above, echo "Hello, world!": This command prints the string "Hello, world!" to the standard output. The "echo" command is used to output text to the ter...