-z is the second supported bash string comparison operator used to check if a string is empty or not. The -z operator functions similarly like -n operator. Below is an example: Most importantly, you should add spaces around the square brackets. If there are no spaces, bash will complain ...
由此,本文就Kotlin如何判断和处理空值,再做进一步的深入探讨。...空指针只是狭义上的空值,广义上的空值除了空指针,还包括其它开发者认可的情况。比如说String类型,字符串的长度为0时也可算是空值;如果字符串的内容全部由空格组成,某种意义上也是空值。...可是上述的
AI代码解释 #include<linux/kernel.h>#include<linux/init.h>#include<linux/module.h>#include<linux/fs.h>#include<linux/uprobes.h>#include<linux/namei.h>#include<linux/string.h>#include<linux/uaccess.h>#defineDEBUGGEE_FILE"/home/zfane/hello/hello"#defineDEBUGGEE_FILE_OFFSET(0x1149)staticstruc...
defined(CONFIG_ENABLE_ARM_SOC_BOOT0_HOOK) */#if !CONFIG_IS_ENABLED(SYS_NO_VECTOR_TABLE)/*** Indirect vectors table** Symbols referenced here must be defined somewhere else***/.globl _reset.globl _undefined_instruction /* 未定义指令异常 */.globl _software_interrupt /* 软中断异常 */...
#include <linux/string.h> #include <linux/uaccess.h> #define DEBUGGEE_FILE "/home/zfane/hello/hello" #define DEBUGGEE_FILE_OFFSET (0x1149) static struct inode *debuggee_inode; static int uprobe_sample_handler(struct uprobe_consumer *con, ...
wc -l –counts the number of lines in the output string, which in this case is the number of items in the directory -eq 0 –does an equality check to compare if the number of items found is equal to 0 Both scripts work correctly to display whether the specified directory is empty. ...
如果if语句后放入一个不能工作的命令,则状态码为非0,且bash shell会跳过then后面的语句。 [22:43:53 root@libin3 libin]# vim shell21 /bin/bash #this is result error if libin then echo "this is error" fi if date then echo "this is success" ...
if [ -z "$1" ]; then # empty string rval="" return fi # wc puts some space behind the output this is why we need sed: numofchar=`echo -n "$1" | wc -c | sed 's/ //g' ` # now cut out the last char rval=`echo -n "$1" | cut -b $numofchar` ...
string:^ 从命令历史中搜索以 string 开头的命令,并获取它的第一个参数 command !string:$ 从命令历史中搜索以 string 开头的命令,并获取它的最后一个参数 command !string:* 从命令历史中搜索以 string 开头的命令,并获取它的所有参数 command !string:n 从命令历史中搜索以 string 开头的命令,并获取它的第n...
(buffer-file-name))) 506 ;; Enable kernel mode for the appropriate files 507 (when (and filename 508 (string-match (expand-file-name "~/src/linux-trees") 509 filename)) 510 (setq indent-tabs-mode t) 511 (c-set-style "linux-tabs-only"))) 512 513 This will make emacs go better...