Linux while loop command is a control flow condition that will help to run the command to execute it repeatedly based on a certain condition. The execution must continue until the condition is validated to be true. The while condition started with the keyword “while” and proceeded by conditio...
do echo "This loop will run forever" sleep 1 done 要停止这种无限循环,你需要使用外部手段,如按下Ctrl+C来中断脚本的执行。 6. 读取文件内容逐行处理 while循环常用于读取文件内容,并对每一行进行处理,下面的脚本读取一个名为file.txt的文件,并将每行内容逆序打印出来: while IFS= read r line do echo "...
Thewhileloop is the best way to read a file line by line in Linux. If you need to read a file line by line and perform some action with each line – then you should use awhile read lineconstruction in Bash, as this is the most proper way to do the necessary. In this article i ...
Always be clear about what is the condition toendthe loop. If that is something that you expect to do yourself with aCTRL-C, then keep an eye on your command. Think abouthow fastyou want each loop cycle to be repeated. If you do any operation that involves I/O inside the loop, tha...
Within its “do” part, we have added the “echo” statement to print the string “hello” on the shell. The “while” loop on one-line ends at the “done” keyword. Let’s save your code and exit to execute it now. Let’s run our file with the Bash command, i.e., using the...
[me@linuxbox~]$while-count12345Finished. The syntax of thewhilecommand is: while 命令的语法是: whilecommands;docommands;done Likeif,whileevaluates the exit status of a list of commands. As long as the exit statusis zero, it performs the commands inside the loop. In the script above, the...
《Linux Command Line and Shell Scripting Bible》Part 13 更多的结构化命令(for while until) for命令 基本语法格式 for var in list do commands done 也可以写成 for var in list; do commands done 读取列表中的值 1 2 3 4 5 6 7 8 9
Command 1 Command 2 ... Command 3 done EXAMPLE 1 - Evaluate and iterate Take a look at the below example. Here I have created a variable"NUM=5"and my condition ($NUM -ne 0) is, the loop will execute if the variableNUMis not equal to zero. $...
嵌套循环( Nested Loop )其实就是多个for、while、until命令嵌套在一起 被嵌套的叫内部循环( Inner Loop ) 写一个简单的例子演示一下,如下图 image 13.6 循环处理文件数据 这个内容其实在上文中的13.1.5 更改字段分隔符小节中就有演示 这里写一个稍微复杂一点的升级版演示一下,如下图 ...
(a term often used in Linux/Bash circles to conceptualize a mini-script written on a single line) will print the numbers 1 to 5 in sequential order. We set a start value for theivariable ($i) by assigning the value1to the same, as the first part of ourforloop definition, terminated...