The string comparison can be a little tricky using the while loop. In the context of shell scripting the-eqare calledinteger comparison operators. So, these operators cannot be used to compare strings. To compare strings in the shell scripting the string comparison operators=,==,!=are used. ...
Example 1: Infinite While loop in a shell script An infinite While loop means your script will run the loop commands non-stop. Infinite While loops never stop running and this occurs when the condition always turns out to be “True.” You can create an infinite While loop with the followin...
read 命令从标准输入读取行,所以 while 循环读取标准输入,直到 EOF 发生。 until循环 until 语句在语法和功能上与 while 语句非常相似。两者之间唯一真正的区别是,当条件表达式为假时,直到语句执行其代码块,而当条件表达式为真时,while 语句执行其代码块。 syntax:until expressiondocommands #bodyofthe loop done 在...
Shell 编程语言提供的另一个迭代语句是 while 语句。 Syntax: while expression do commands done 在上面的while循环语法中: while、do、done 是关键字 表达式是返回标量值的任何表达式 While 语句导致在提供的条件表达式为真时执行代码块。 Bash While 示例 3. 将内容写入文件 以下示例从标准输出读取数据并写入文件。
For example, you can run UNIX command or task 5 times or read and process list of files using a for loop. A for loop can be used at a shell prompt or within a shell script itself. for loop syntax Numeric ranges for syntax is as follows: ...
The bash loop constructs include the for loop, while loop, and until loop. 👉 Sometimes, you may find references to a select loop in bash. It is not part of the bash loop constructs. You can read more about the select-loop in my post How To Create Simple Menu with the Shell ...
while[condition]docommand1 command2 command3done condition为true时命令1到命令3将会一直执行,知道条件为false ,例如: #!/bin/bashx=1while[$x-le5]doecho"Welcome $x times"x=$(($x+1))done Here is a sample shell code to calculate factorial using while loop: ...
One can use the for loop statement even within a shell script. While the For Loop is a prime statement in many programming languages, we will focus on how to use it for the bash language. Are you ready to add yet another tool to your developer arsenal? Let’s explore deeper into the...
Using a "do while" loop in bash scripting is simple. Here, ‘-le’ keywords indicate the "less than or equal" sign of a normal programming language. The following script will run until the variable's value is greater than five. #!/bin/bash echo "Do while loop example" a=1 while [...
while [ $x -le 5 ] do echo "Welcome $x times" x=$(( $x + 1 )) done 1. 2. 3. 4. 5. 6. 7. Here is a sample shell code to calculate factorial using while loop: #!/bin/bash counter=$1 factorial=1 while [ $counter -gt 0 ] ...