在Linux中,if else语句中可以使用逻辑运算符来组合多个条件。常用的逻辑运算符包括: 逻辑与(AND):用"&&"表示,表示只有所有条件都为真时,整个条件才为真。 逻辑或(OR):用"||"表示,表示只要有一个条件为真时,整个条件就为真。 逻辑非(NOT):用"!"表示,表示对条件进行取反。 例如,以下是一个if else语句中...
If recollecting were forgetting, 我将不再回忆. Then I remember not. 如果忘却就是记住, And if forgetting, recollecting, 我多么接近于忘却. How near I had forgot. 如果相思,是娱乐, And if to miss, were merry, 而哀悼,是喜悦, And to mourn, were gay, 那些手指何等欢快,今天, How very blithe...
-a逻辑AND,两个条件都需为true。例如:[ var1 -a var2 ] -o逻辑OR,两个条件中任一个条件都为true。例如:[ var1 -o var2 ] !逻辑NOT,取反条件例如:[ ! "var1" = "var2" ] 4. if语句的例子 来看一个if语句的例子,来演示中括号在表达式中的用法: bash #!/bin/bash num1=10 num2=20 if ...
if [[ ( $num -lt 10 ) && ( $num%2 -eq 0 ) ]]; thenecho "Even Number"elseecho "Odd Number"fi AND运算符由&&符号表示。 11.使用OR运算符 OR运算符是另一个关键的构造,它允许我们在脚本中实现复杂、健壮的编程逻辑。与AND相反,当OR运算符的任一操作数为真时,由OR运算符组成的语句返回真。仅...
dd - convert and copy a file [root@ping ~]# dd if=/dev/zero of=/dev/sdb1 bs=4096 count=10 生成一个文件系统 mke2fs - create an ext2/ext3/ext4 filesystem [root@ping ~]# mkfs.ext4 /dev/sdb1 格式化文件系统/dev/sdb1 测试手动挂载: ...
/bin/bash for user in `awk -F: '($3 < 500) {print $1 }'/etc/passwd`; do if [ $user != "root" ] then /usr/sbin/usermod -L $user if [ $user != "sync" ] && [ $user !="shutdown" ] && [ $user != "halt" ] then /usr/sbin/usermod -s /sbin/nologin $user fi...
[ ARG1 OP ARG2 ] “OP” is one of-eq, -ne, -lt, -le, -gt or-ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than, less than or equal to, greater than, or greater than or equal to “ARG2”, respectively. “ARG1” and “ARG2...
Ubuntu is the modern, open source operating system on Linux for the enterprise server, desktop, cloud, and IoT.
in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications ...
1.nginx的配置中不支持if条件的逻辑与/逻辑或运算,并且不支持if的嵌套语法,我们可以用变量的方式来实现: 具体方法为AND就用变量叠加,OR就用0或1切换。 1)首先是伪代码(即不被nginx支持)写在这里只是为了方便理解: if($remote_addr~"^(12.34|56.78)"&&$http_user_agent~*"spider"){ ...