The exit code of the last command you run For every Linux command you run on a shell, it must return an exit status. Usually, the exit status is represented with an integer number, where 0 means that the script/command worked successfully without errors. Any other number besides zero (0)...
(If n is omitted, the exit status is that of the last command executed. ) 格式:$? 上一个命令的退出码。 格式:trap "commands" EXIT 退出时执行commands指定的命令。( A trap on EXIT is executed before the shell terminates.) 退出码(exit status,或exit code)的约定: 0表示成功(Zero - Success...
Shell Command Exit Status The return value of a command is its exit status, or 128 + N if the command is terminated by signal N. Exit status is used to check the result (success/failure) of the execution of the command. If the exit status is zero, then the command is success. If ...
exit_status=$? 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" Prin...
Bash exit command The exit command exits the shell with a status of N. It has the following syntax: exit N Copy If N is not given, the exit status code is that of the last executed command. When used in shell scripts, the value supplied as an argument to the exit command is retur...
CentOS 8 查看 IP 报错:bash: ifconfig: command not found在使用 CentOS 8 系统时,有时会遇到使用 ifconfig 命令查看网络接口信息时出现 bash: ifconfig: command not found 的错误。这是因为从 CentOS 7 开始,系统默认不再安装 net-tools 包,而 ifconfig 命令正是包含在这个包中的。 IP 网络接口 CentOS ...
$? # Exit status of last task $! # PID of last background task $$ # PID of shell $0 # Filename of the shell script $_ # Last argument of the previous command 检查命令返回值 if ping -c 1 google.com; then echo "It appears you have a working internet connection" fi 检查grep 的...
Bash's exit status is the exit status of the last command executed in the script. If no commands are executed, the exit status is 0. An attempt is first made to open the file in the current directory, and, if no file is found, then the shell searches the directories in PATH for ...
Exit status 1 Using the above example but adding in the long listing and recursive options (-lR), you receive a new exit code of 1: $ls-lR/etc **A lengthy list of files** $echo$?1 Although the command's output looks as though everything went well, if you scroll up you will see...
/* WHILE command. */typedef struct while_com{int flags;/* See description of CMD flags. */COMMAND*test;/* Thing to test. */COMMAND*action;/* Thing to do while test is non-zero. */}WHILE_COM; 等等。 主要流程 以下所涉及文件如无特殊说明均处于bash源码的根目录下。 对于一行bash命令的执...