# 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:...
(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 + echo 1 1 + set +x + echo 2 2 + s...
/bin/bashset-eSCRIPT_DIR="$( cd "$( dirname"${BASH_SOURCE[0]}")" && pwd )"# get UBUNTU_CODENAME, ROS_DISTRO, REPO_DIR, CATKIN_DIRsource $SCRIPT_DIR/identify_environment.bashcd"$HOME/catkin_ws/src"rm CMakeLists.txtgit clone https://gith...
(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...
/bin/bash2# 示例代码: 冒号 colon,空命令nullcommand3# 例1:死循环 Endless loop45while: #本行等同于whiletrue6do7operation-18operation-29opreation-310operation-411done1213#例2:if/then的占用符 placeholder1415ifcondition16then: #什么都不做,引出分支,有可能以后补充17else18take-some-action19fi2021#...
如何在bash shell script.Here的if语句中给出两个或多个条件我有一个名为opt的变量。如果else值为1、2或3,则If块应执行否则opt块。 浏览1提问于2013-03-26得票数 1 回答已采纳 2回答 如何编写一个while循环来检查Ruby中的"Y“或"N”字符? 我正在尝试编写一个while循环,强制我的用户通过键入"Y“或”N“...
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 ...
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 所有条件均不满足时的分支 fi 练习: 1.通过命令行参数给定两个数字,输出其中较大的数值 2.通过命令行参数给定一个用户名,判断其ID号是偶数还是奇数; 3...
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 ...
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。