The “$?” is a built-in variable that your shell uses to store the exit status code of the last executed command in integer format and remains unchanged unless the next command is executed. Using this exit status code, you can debug the problem that occurred while executing the command, ...
]] [-T last_check_time] [-U UUID] [-I new_inode_size] [-z undo_file] device 这些命令可以帮助管理员在日常维护中监控磁盘空间使用情况、挂载和卸载文件系统、创建和修复文件系统,以及调整文件系统的参数。熟练掌握这些命令可以提高文件系统管理的效率和准确性。 3 SWAP管理 Swap是一种用于扩展Linux系统...
the exit status will be 1 since false exits with code 1. Let’s see this in a practical manner. First, issue the true command and check the exit status:
Again, the error message points to a error that occurs later than the actual problem. What happens is really pretty interesting. As we recall, if accepts a list of commands and evaluates the exit code of the last command in the list. In our program, we intend this list to consist of a...
To illustrate how to handle return codes from a shell command, check this simple playbook: ---name:Executes a shell scripthosts:localhostgather_facts:notasks:-name:Execute the shell scriptshell:./myscript.shignore_errors:trueregister:result-name:Shows the result of executing the scriptdebug:msg...
Every function in shell scripting returns some value, the dafault return value is the exit code/status code of the last command inside function. But based on our requirement, we can return values explicitly by using the return statement return <exit_code>, the allowed values are in the range...
You will occasionally run into a program that requires this type of redirection, but because mostUnixcommands accept filenames as arguments, this isn’t very common. For example, the preceding command could have been written as head /proc/cpuinfo. ...
68//执行命令69voidExecuteCommand()70{//创建子进程71pid_t id=fork();72if(id==0)73{//进程替换74execvp(gArgv[0],gArgv);75exit(errno);76}77else78{79int status=0;80pid_t rid=waitpid(id,&status,0);//进程等待81if(rid>0)82{//如果错误打印错误信息83int lastcode=WEXITSTATUS(status)...
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function check_cores { [ -z $1 ] && REQ_CORES=2 CPU_CORES=$(grep -c name /proc/cpuinfo) if (( CPU_CORES < REQ_CORES )) ; then echo "A minimum of $REQ_CORES cores are required" exit 1 fi } 如果向函数传递了参数,则将其用作所需的核心数;否则,我们将默认值设置为2。如果我们在...