Bash Select Command, Fahmida Yesmin 14.Bash 函数本章介绍 Bash 函数的用法。简介函数(function)是可以重复使用的代码片段,有利于代码的复用。它与别名(alias)的区别是,别名只适合封装简单的单个命令,函数则可以封装复杂的多行命令。函数总是在当前 Shell 执行,这是跟脚本的一个重大区别,Bash 会
方法一:typeset C=(expr{A} + B);SHELL中的基本工具,优点:方便检测变量是否为数字;缺点:只能计算整数,且只能计算加减法,不能计算乘除法方法二:let"C={A}+B";或let"C=A+B"内嵌命令计算,优点:能计算乘除法及位运算等;缺点:只能计算整数方法三:typesetC=((A+B)) CShell风格的计算,优点:能计算乘除法...
In this example we declare simple bash variable and print it on the screen ( stdout ) with echo command. #!/bin/bash STRING="HELLO WORLD!!!" echo $STRING 1. 2. 3. Your backup script and variables: #!/bin/bash OF=myhome_directory_$(date +%Y%m%d).tar.gz tar -czf $OF /home/l...
#! /bin/bash echo "enter 1st string" read st1 echo "enter 2nd string" read st2 if [ "$st1" \< "$st2" ] then echo "$st1 is smaller than $st2" elif [ "$st1" \> "$st2" ] then echo "$st2 is smaller than $st1" else echo "both strings are equal" fi 拼接两个字符串 #!
# Create the variable name. $ var="world" $ ref="hello_$var" # Print the value of the variable name stored in 'hello_$var'. $ printf '%s\n' "${!ref}" value 1. 2. 3. 4. 5. 6. 7. 8. 9. 或者,在bash4.3+上:
typeset:typeset[-aAfFilrtux][-p]name[=value]... Setvariable valuesandattributes. Obsolete.See`help declare'. [root@-shiyan prog]# type -a fdisk for cd fdisk is /sbin/fdisk for is a shell keyword cd is a shell builtin [root@-shiyan prog]# type -t fdisk for cd ls __udisks ...
a_var="world" # Output: bash: read-only variable: a_var 删除变量 使用unset 命令可以删除变量,但是不能删除只读变量。 变量被删除后不能再次使用。 my_var="haha" unset my_var echo ${my_var} # 变量my_var已被删除,没有任何输出 变量的类型 诸如C、Java、Python等这些高级语言中的变量是有...
As a locally scoped environment variable: $ NAME=Abid Now, the point is how to display environment variables. We can use toechodisplay environment variables like normal variables. $echo$COUNTRY Output: USA The output of this command will be the value we assigned to this variable COUNTRY, which...
看到哪里或者为什么脚本没有正常工作.在 commented-script1.sh 例子中,可以这么做, 依然假设显示用户这部分出了问题: echo "debug message: now attempting to start w command"; w 在更高级的脚本中,echo 可以插入到在不同的阶段显示变量表,因此可以检查到错误: echo "Variable VARNAME is now set to $VAR...
Variables can be assigned with the equal sign (=) operator. Strings or numbers can be assigned to variables. The value of a variable can be accessed with the dollar sign ($) before the variable name. You can use the dollar sign and parentheses syntax (command substitution) to execute a ...