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. ...
In Linux,whileloopsare essential tools for automating repetitive tasks and controlling the flow of programs.These loops enable us to execute a block of code repeatedly, provided that a specified condition is true. Moreover,whileloops are versatile in that we can include user input as the specifie...
AWK Linux shell变量调用shell变量 $ cat tst.sh#!/usr/bin/env bashmyloop() { echo "col=$*" awk -v c1="$1" -v c2="$2" -v l1="$3" -v l2="$4" ' { xy += $c1 * $c2 } END { print "Product", l1, "and", l2 print "prod =", xy+0 } ' file1}myloop 2 3 h2 ...
shell脚本elsesshell脚本while while循环循环语句常用于重复执行一条指令或一组指令,直到条件不满足停止,shell脚本语言的循环语句常见的有while、until、for、select循环语句,其中,until和select已经基本淡出历史舞台。本章讲while循环while循环语句主要用来重复执行一组命令会语句。在企业中常用于守护进程或持续运行的程序,也...
Shell脚本中的whilegetopts用法小结 getpots是Shell命令行参数解析工具,旨在从ShellScript的命令行当中解析参数。getopts被Shell程序用来分析位置参数,option包含需要被识别的选项字符,如果这里的字符后面跟着一个冒号,表明该字符选项需要一个参数,其参数需要以空格分隔。冒号和问号不能被用作选项字符。ge ...
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...
In Bash scripting, the while loop functions by repeating a set of instructions as long as the specified condition is true.
Shell while 循环while 循环用于不断执行一系列命令,也用于从输入文件中读取数据;命令通常为测试条件。其格式为:while command do Statement(s) to be executed if command is true done命令执行完毕,控制返回循环顶部,从头开始直至测试条件为假。以下是一个基本的 while 循环,测试条件是:如果 COUNTER 小于5,那么...
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 variablecountis created and assigned an initial value of 1. Thewhilecommand evaluates theexit status of thetestcommand. As long...