One of the many scripting constructs is the loop. A loop is a section of code that picks up data or generates data and then performs some operation on the data and then begins the process over again until some condition is met, the script is disrupted, or when input data is exhausted. ...
转自:linux按行读取 (while read line与for-loop) 在linux下一般用while read line与for循环按行读取文件。现有如下test.txt文件: 1. while read line whileread line;doecho $line done< test.txt 输出结果与上图一致。 这里也可以写为: cat test.txt |whileread line;doecho $line done 输出结果一致,但...
9.Scripts本章同步视频:https://edu.51cto.com/sd/e4874 9.5循环 (loop) 9.5.1 while do done 1.格式与说明 while condition do statements done condition表示判断条件,statements表示要执行的语句(可以只有一条,也可以有多条),do和done都是 Shell 中的关键字。 while 循环的执行流程为: u先对 condition 进...
linux按行读取 (while read line与for-loop) 1. while read line 代码语言:javascript 代码运行次数:0 运行 AI代码解释 whileread line;doecho $line done<test.txt 输出结果与上图一致。 这里也可以写为: 代码语言:javascript 代码运行次数:0 运行 AI代码解释 cat test.txt|whileread line;doecho $line don...
In this final chapter on flow control, we will look at another of the shell’s looping constructs.The for loop differs from the while and until loops in that it providesa means of processing sequences during a loop. This turns out to be very useful when programming.Accordingly, the for ...
for (( i=1; i<=100; i++ )) do s=$(( $s + $i )) done echo $s sh add.sh 报错: add.sh: 4: Syntax error: Bad for loop variable 代码没有错误,Ubuntu为了加快开机速度,用dash取代bash。 解决的方法:取消dash,使用bash: sudo dpkg-reconfigure dash ...
在linux下一般用while read line与for循环按行读取文件。现有如下test.txt文件: 1. while read line whileread line;doecho $line done<test.txt 1. 2. 3. 复制 输出结果与上图一致。 这里也可以写为: cat test.txt|whileread line;doecho $line ...
For example, you can add the nested loop example to a Bash script to improve its readability, like this: $vimcopy_web_files.sh# !/bin/bashforiinfile{1..3};doforxinweb{0..3};doecho"Copying$ito server$x"scp$i$xdonedone When you save and execute this script, the result is the ...
fruit=orange; and on the third and final iteration,fruit=pear. Once it has completed the loop, the script continues normal execution with the next command after thedonestatement. In this case, it ends by saying “Let’s make a salad!” to show that it has ended the loop, but not the...
SQL 过程中的 LOOP 语句 LOOP 语句是特殊类型的循环语句,原因是它没有终止条件子句。它会定义重复执行的一系列语句直到另一块逻辑(通常是控制转移语句)强制控制流跳至循环外部某点。 LOOP 语句通常与下列其中一个语句配合使用:LEAVE、GOTO、ITERATE 或 RETURN。这些语句可强制控制权跳至 SQL 过程中紧跟循环之后的...