In a bash script, using the conditional "or" in an "if", This question is a sequel of sorts to my earlier question.The users on this site kindly helped me determine how to write a bash for loop that iterates over string values. For example, suppose that a loop control variable fname...
上面语法中,options是参数选项,variable是用来保存输入数值的一个或多个变量名。如果没有提供变量名,环境变量REPLY会包含用户输入的一整行数据。下面是一个例子demo.sh。#!/bin/bash echo -n "输入一些文本 > " read text echo "你的输入:$text"上面例子中,先显示一行提示文本,然后会等待用户输入文本。用户...
详细见列表: 格式说明 ${string: start :length} 从 string字符串的左边第 start 个字符开始,向右截取 length 个字符。 ${string: start} 从 string字符串的左边第 start 个字符开始截取,直到最后。 ${string: 0-s ... 字符串 字符串截取 转载
You can assign data to a variable using the equals sign (=). The data you store in a variable can either be a string or a number. Let’s create a variable now on the command line: chapter_number=5 The variable name is on the left hand side of the equals sign, and the data whic...
long_variable_name_which_may_tell_you_something_about_its_purpose=1 一个变量的范围:你能从这里看到它吗? 默认情况下,变量的定义只有定义它的 shell(以及该 shell 的子 shell)知道。调用当前脚本的脚本不会知道这个变量,被当前脚本调用的脚本也不会知道这个变量,除非它被导出到环境。 环境是一个形式为name...
[student@studentvm1 testdir]$ expr length "We can also find the length of a literal string as well as a variable." 70 关于比较操作符,在我们的脚本中使用了大量的检测两个字符串是否相等(例如,两个字符串是否实际上是同一个字符串)的操作。我使用的是非 POSIX 版本的比较表达式: ...
[student@studentvm1 testdir]$ expr length "We can also find the length of a literal string as well as a variable." 70 关于比较操作符,在我们的脚本中使用了大量的检测两个字符串是否相等(例如,两个字符串是否实际上是同一个字符串)的操作。我使用的是非 POSIX 版本的比较表达式: ...
test "this string" = "that string" test 1 = 001 test 1 -eq 001 In each case, we usetheechocommandto print the return code of the last command. Zero means true, one means false. Using the equals sign "=" gives us a false response comparing 1 to 001. That's correct, because the...
Mind that in order to assign a new variable, you will need to use an equals sign (=). We will use the echo command to print out the variable value. We also need to use a dollar sign ($), so the bash knows we need variable value. Lastly, run the script using this bash command...
bash shell参数展开(Shell Parameter Expansion):替换变量(variable)中的字符串 在写bash shell脚本时,如果遇到要替换变量中的字符串,首先想到的就是用sed命令,比如下面的示例将变量str中的数字123替换成UUU: $ str=hello,word,123 $ echo...$str | sed -E -e 's/[0-9]/U/g' hello,word,UUUU 上面的...