[ STRING1 > STRING2 ] 如果 “STRING1” sorts after “STRING2” lexicographically in the current locale则为真。 [ 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,...
echo "$a : The string is empty" fi 结果 abc = efg: a != b -n abc : The string length is not 0 abc : The string is not empty 文件测试运算符 实例: #!/bin/bash file="/home/shiyanlou/test.sh" if [ -r $file ] then echo "The file is readable" else echo "The file is no...
当有多个表达式(条件)时,可以使用elif(else-if)语句。看下面的例子,我们创建一个名为 age.sh 的脚本: 复制 #!/bin/bashAGE=$1if[$AGE-lt13]; thenecho"You are a kid."elif[$AGE-lt20]; thenecho"You are a teenager."elif[$AGE-lt65]; thenecho"You are an adult."elseecho"You are an ...
递归遍历如下:将已知路径和列表数组作为参数传递, public void Director(string dir,List list) { DirectoryInfo d...d.GetDirectories();//文件夹 foreach (FileInfo f in files) { list.Add(f.Name);//添加文件名到列表中...} //获取子文件夹内的文件列表,递归遍历 foreach (DirectoryInfo dd ...
filename1 -ot filename2 如果 filename1 比 filename2 旧,则为真 [ /boot/bzImage -ot arch/i386/boot/bzImage ] 1. 2. 3. 4. 5. 6. 7. 8. 9. 字符串比较运算符 (请注意引号的使用,这是防止空格扰乱代码的好方法) -z string 如果 string 长度为零,则为真 [ -z $myvar ] ...
bash 中的条件语句，基础就是 Test 。 if 先来个实例： x=5; if [ $x = 5 ]; then e...
shortcut. Coming back to the terminal, we are using the Bash instruction to run this Bash file, i.e., empty.sh. On execution, it returns “Empty” because the string “str” is initialized empty in the code, and the “then” part of the “if-else” statement has been executed so ...
/bin/bashstr=if[$str=="string"];thenecho"Go on!"fi 代码将不会执行并产生错误。未分配的变量"str"与单方括号一起使用。 使用bash -x file.sh命令再次执行该文件以对其进行调试。 输出: 如你所见,等式左侧没有值,这会导致错误。 如果将变量写在双引号中,则不会出现此错误。因为现在比较操作会变成'' ...
在这个简短的 CLI 程序中,修改$File变量的值相比于在多个地方修改表示文件名的字符串的值要容易: [student@studentvm1 testdir]$ File="TestFile1" ; if [ -e $File ] ; then echo "The file $File exists." ; else echo "The file $File does not exist." ; fi ...
Check if String Starts with Another String in Bash Read more → 6. Using sed with grep Command The sed (Stream Editor) is a powerful and versatile text processing tool that performs text transformations on an input stream (a file or input from a pipeline). Here, we will use sed for ...