如果语句不为真,则 shell 跳过 If 语句块的末尾并继续执行。 在本指南中,我们将解释如何在 bash 脚本中使用 if 语句。在 bash shell 脚本中,If 语句可以以 If、If- else、If- If- else、netsted If 和 case 的形式使用。 If Statement Syntax: if [ condition_command ] then command1 command2 ……....
*)statementnesaccase、in 和 esac 都是 Shell 关键字，expression 表示表达式，pattern 表示匹配模式。e...
Shell 有三种 if ... else 语句: if ... fi 语句; if ... else ... fi 语句; if ... elif ... else ... fi 语句。 语法格式: if [ expression ] then Statement(s) to be executed if expression is true fi ## 注意, expression 和方括号([ ])之间必须有空格,否则会有语法错误。 if ...
2. How do I write an if statement in a shell script? Writing an if statement in a shell script involves specifying a condition and the actions to take if the condition is true. Here’s the basic syntax: if[condition];then# code to execute if condition is trueelse# code to execute if...
In this example, the script first checks if ‘a’ is greater than ‘b’. If it’s not, it moves on to the ‘elif’ statement to check if ‘a’ is greater than ‘c’. If neither condition is met, it executes the ‘else’ statement, which in this case, prints ‘a is not greate...
A Shell script usually needs to test if a command succeeds or a condition is met. In Bash, this test can be done with a Bash if statement. As with any other programming language, Bash comes with conditional expressions that allow you to test for conditions and alter the control flow if ...
#提前准备好用户的文件[root@VM_0_10_centos shellScript]#vi username.txttest01 test02 test03 test04 test05 test06#vi example.sh#!/bin/bashread -p"请输入用户密码:"PASSWDforUNAMEin`cat username.txt`doid$UNAME&> /dev/nullif[ $?-eq0] ...
在C Shell脚本中,if语句用于根据条件执行不同的代码块。if语句的语法如下: ``` if (表达式) then # 执行语句块1 else if (表达式) then #...
If we were to convert the script above to a shell function to includeit in a larger program, we could replace the exit commands with return statementsand get the desired behavior: 类似地,通过带有一个整数参数的 return 命令,shell 函数可以返回一个退出状态。如果我们打算把上面的脚本转变为一个 ...
bash shell if-statement while-loop m3u 我正在编写一个脚本来解析m3u文件。目标是检索变量标记和url。我用这个文件做了测试。 #!/bin/bash echo "name,tvg-id,tvg-name,tvg-country,group-title,languages,url" while IFS= read -r line; do tags_detect="$(echo "$line" | grep -Eo '^#EXTINF:')...