最后要介绍的是 shell script 设计中常见的"循环"(loop)。所谓的 loop 就是 script 中的一段在一定条件下反复执行的代码。 bash shell 中常用的 loop 有如下三种: * for * while * until for loop 是从一个清单列表中读进变量值,并"依次"的循环执行 do 到 done 之间的命令行。 例: for var in one ...
In shell scripting, using user input as a condition for awhileloop adds dynamic executionas it enables us to control the flow of the script based on their input. 3.1. Prompting for User Input To demonstrate, let’s utilize thereadcommand to prompt the user: $ read -p "message prompt" v...
3、/etc/rc.d/rc3.d目录下分别有多个以K开头和以S开头的文件;分别读取每个文件,以K开头的输出为文件加stop,以S开头的输出为文件名加start,如K34filename stop S66filename start for files in /etc/rc.d/rc3.d/[KS]* ;do if [ `basename $files|cut -c1` == "K" ] ;then echo "$files stop...
Shell scripting, specifically Bash scripting, is a great way to automate repetitive or tedious tasks on your systems. Why type when you can schedule and run scripts in a hands-free manner? One of the many scripting constructs is the loop. A loop is a section of code that picks up data ...
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.” ...
Shell编程中循环命令用于特定条件下决定某些语句重复执行的控制方式,有三种常用的循环语句:for、while和until。while循环和for循环属于“当型循环”,而until属于“直到型循环”。循环控制符:break和continue控制流程转向。 参考:《Linux 与unix shell 编程指南》 ...
在停止while循环在输出中重复的问题上,可以采取以下几种方法: 1. 使用break语句:在while循环内部设置一个条件,当满足该条件时,使用break语句跳出循环。这样可以确保循环在满足条件后...
script标签可以放在页面的任何位置,一般在head和body中。当引入文件和内部js同时存在时,内部js不会执行。 不能使用的单标签。 js 语句严格区分大小写。...Math.round()四舍五入(针对整数) 4.逻辑控制与流程控制 (a) if语句: if (bool表达式){ 语句 } else if (bool表达式){ 语句 }...语句: while(...
bash shell if-statement while-loop m3u 我正在编写一个脚本来解析m3u文件。目标是检索变量标记和url。我用这个文件做了测试。 #!/bin/bash echo "name,tvg-id,tvg-name,tvg-country,group-title,languages,url" while IFS= read -r line; do tags_detect="$(echo "$line" | grep -Eo '^#EXTINF:')...
To compare strings in the shell scripting the string comparison operators=,==,!=are used. Let’s create a Bash script to take the username as input from the user and compare the name string with the hardcoded name. #!/bin/bash