# commands to execute if condition is true elif [ another_condition ]; then # commands to execute if another_condition is true else # commands to execute if none of the above conditions are true fi [ condition ]:方括号内是条件表达式,用于判断条件是否为真,注意,方括号两侧必须有空格。 then:...
Conditions in bash scripting (if statements) - Linux Academy Blog https://linuxacademy.com/blog/linux/conditions-in-bash-scripting-if-statements/ Table of conditions The following table list the condition possibilities for both the single- and the double-bracket syntax. Save a single exception, th...
(2) 如果参数为“start”, 则创建空文件/var/lock/subsys/script.sh,并显示“starting script.sh successfully.”; (3) 如果参数为“stop”,则删除空文件/var/lock/subsys/script.sh,并显示“stopping script.sh successfully.”; (4) 如果参数为“restart”,则删除空文件/var/lock/subsys/script.sh,并显示...
if 测试条件 then; 或 if 测试条件 then 代码分支代码分支 fifi 双分支的if语句: if 测试条件;then 条件为真时执行的分支 else 条件为假时执行的分支 fi 多分支if语句 if CONDITION1;then 条件1为真分支 elif CONDITION2;then 条件2为真分支 elif CONDITION3;then 条件3为真分支 ... else 所有条件均不满...
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 greater than either b or ...
if[ condition-is-true]thencommand1elif [ condition-is-true];thencommand2elif [ condition-is-true]thencommand3elsecommand4fi case语句,case可以实现和if一样的功能,但是当条件判断很多的时候,使用if不太方便,比如使用if进行值的比较。 #!/bin/bashread -p"E...
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 ...
if语句 条件测试 bash条件判断之if语句(二) 练习19:写一个脚本:可以接受一个参数,其使用形式如下:script.sh {start|stop|restart|status}如果参数为start,创建空文件/var/lock/subsys/script,并显示“Starting script successfully.”;如果参数为stop,则删除文件/var/lock/subsys/script,并显示“Stop script if语...
bash script 编程基础 1.何谓shell script shell script是利用shell的功能写一个“程序”,这个程序是使用纯文本文件,将一些shell的语法与命令写在里面。2.脚本或程序源文件都是纯文本文件。3.脚本或程序的执行一般有两种方式: 编译执行:预处理-->编译-->汇编-->链接;编译执行是一种计算机语言的执行方式。
(1)bash -x script.sh or sh -x script.sh (2)使用set -x和set +x对脚本进行部分调试。例如: #!/bin/bash #filename:debug.sh for i in {1..6}; do set -x echo $i set +x done echo "script executed" [cairui@cai shell]$ sh debug.sh ...