(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...
use umask 022 if you want everyone to be able to see all of the files and directories that you create, and use umask 077 if you don’t. (You’ll need to put the umask command with the desired mode
asmlinkage __visible void __init start_kernel(void) { char *command_line; char *after_dashes; ... early_irq_init(); init_IRQ(); ... } 在init_IRQ 中,调用了machine_desc->init_irq(): void __init init_IRQ(void) { int ret; if (IS_ENABLED(CONFIG_OF) && !machine_desc->init_ir...
the utility nm-online will tell you whether the network is up or down. If the network is up, the command returns zero as its exit code; it’s nonzero otherwise. (For more on how to use an exit code
No effect; the command does nothing beyond expanding argumentsandperforming any specified redirections. A zero exit codeisreturned. 举例如下: [root@iZ2ze2m3z176dpbiaolifiZ ~]#help cdcd: cd [-L|[-P [-e]]] [dir] Change the shell working directory. ...
If exit codes are not set the exit code will be the exit code of the last run command.How to get the exit code of a command To get the exit code of a command type echo $? at the command prompt. In the following example a file is printed to the terminal using the cat command....
t change a partition's system idv verify the partition tablew write table to disk and exitx extra functionality (experts only)--例子 p-打印现有分区,d-删除分区,n-新建分区,w-保存并写入磁盘Command (m for help): pDisk /dev/sda: 200 GiB, 214748364800 bytes, 419430400 sectorsDisk model: Virtu...
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 ...
The command is called cat because it performs concatenation when it prints the contents of more than one file. 当你运行这个命令时,cat会打印文件1、文件2以及你指定的其他文件(用...表示)的内容,然后退出。 cat命令之所以被称为cat,是因为当它打印多个文件的内容时,它执行了连接操作。 2.2.3 Standard ...
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...