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,...
(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...
To get the exit code of a command If you want to get the bash result of a last command, you have to introduce the $? variable after the “echo” command. Alternatively, you can use the printf command: Example: If the code doesn’t run properly, the exit code will be 1 or any ot...
Captures the exit status code of the previously executed command. $? is a special variable that holds the exit status of the last executed command. Stores the exit status in the variable 'exit_status'. Print the exit status code: echo "Exit status code: $exit_status" ...
命令COMMAND结构描述一条bash命令,对于复合命令,其内部可能还包含有其他命令: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 typedef struct command{enumcommand_type type;/* FOR CASE WHILE IF CONNECTION or SIMPLE. */int flags;/* Flags controlling execution environment. */int line;/* line number...
of the last child in the pipeline is the significant one. If the command or job was terminated by a signal, note that value also. */ termination_state = (job != NO_JOB) ?job_exit_status(job)一般通过这个流程来确定返回值。 :process_exit_status(child->status); ...
/* Read commands until exit condition. */ reader_loop (); exit_shell (last_command_exit_value); } 函数定义了shell启动和运行过程中的一些状态变量,依据不同的参数初始化shell:shell_initialize ()初始化了shell变量和参数,run_startup_files ()执行需要的配置文件(/etc/profile和~/.bashrc等)。
$!" # 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, ...