每种编程语言都有 loop 操作,在 bash script 中,有两种 loop 。 while 没数的时候就用While吧,没数但必须说一个条件。 #!/bin/bash i=0 while [ $i -le 4 ] do echo Number: $i ((i++)) done for 数数或者数list。 #!/bin/bash i=2 for (( counter=1; counter<=10; counter++ )) do...
for (( COUNTER=1; COUNTER<10; COUNTER++ )) ; do printf “The counter is now %d/n” “$COUNTER” done exit 0 当循环开始时,执行双括号中的第一个表达式,每次循环开始执行第三个表达式,并检查第二个表达式,当第二个表达式返回 false ,循环结束。 $ bash forloop.sh The counter is now 1 The c...
#The value is:4#The value is:5#The value is: kk num=0forstrin'This is a string'donum=`expr$num +1`echo$str $num #-->This is astring1;只执行一次done 4. while循环 #!/bin/bash COUNTER=0while[ $COUNTER -lt3]doCOUNTER=`expr$COUNTER +1`done 5. until循环 #!/bin/bash #until...
After each iteration of the loop, expr3 is evaluated. This is usually used to increment a loop counter. The following 12 examples shows how to bash for loops in different ways. 1. Static values for the list after “in” keyword In the following example, the list of values (Mon, Tue, ...
下面的列表 7.1 示例使用了 for 循环嵌入 let 命令的表达方式: 列表7.1 代码语言:js 复制 #!/bin/bash# forloop.sh:Count from1to9for((COUNTER=1;COUNTER<10;COUNTER++));doprintf “The counter is now%d/n” “$COUNTER” done exit0 当循环开始时,执行双括号中的第一个表达式,每次循环开始执行第三...
Bash example for the += and -= counter operators in a while loop: #!/bin/bash num=0 while(($num<6)) do echo "num:" $num ((num+=1)) done Script output: foc@fedora:/tmp$ ./counter.sh num: 0 num: 1 num: 2 num: 3 num: 4 num: 5 You can also write let num+=1 ins...
After each iteration of the loop, expr3 is evaluated. This is usually used to increment a loop counter. The following 12 examples shows how to bash for loops in different ways. 1. Static values for the list after “in” keyword
This type offorloop expects a list of values/elements and performs a single iteration for each element in the list. The list can be provided by separating each item in a single space, or you may specify a range. forCounterin1 2 3 4 5..Ndo1st statement 2nd statement nth statementdone ...
# test a loop counterN = lengthofarrayloopwith indices:ifi==N-1:printa[i] else:printa[i],"or" Run Code Online (Sandbox Code Playgroud) 请注意,这种情况需要您知道有多少个元素,并且它会不断测试索引。因此,您必须循环索引,或者单独跟踪索引(在循环之前设置 i=0,在循环内部设置 i++)。
doneis the closing part of the loop. Sounds complex? Let me show you a simple example. #!/bin/bash counter=1 until [ $counter -gt 10 ]; do echo $counter ((counter++)) done The above script is nothing but a loop that will be iterated until the value of thecountervariable is great...