-x file 测试文件对当前用户是都可执行 -z 是否为空 为空则为真 -a 是否不空 五、if语法 if 判断条件 0为真 其他都为假 单分支if语句 if 判断条件;then statement1 statement2 ... fi 双分支的if语句: if 判断条件;then statement1 statement2 ... else statement3 statement4 fi Note: if语句进行判...
echo"3. Multiplication"echo-n"Please choose a word [1,2 or 3]? "read operif[$oper-eq1]then echo"Addition Result "$(($inp1+$inp2))elseif[$oper-eq2]then echo"Subtraction Result "$(($inp1-$inp2))elseif[$oper-eq3]then echo"Multiplication Result "$(($inp1*$inp2))elseecho"Inva...
而if [ ! -z err]||[!−eapk ]; then 没问题; 整数比较 : -eq 等于,如:if [ "a"−eq"b" ] -ne 不等于,如:if [ "a"−ne"b" ] -gt 大于,如:if [ "a"−gt"b" ] -ge 大于等于,如:if [ "a"−ge"b" ] -lt 小于,如:if [ "a"−lt"b" ] -le 小于等于,如:if...
/bin/bash #表明该脚本使用sh或bash2#This is a sample34#usage of variable5year=1999; #变量赋值语句67#usage of expression8year=`expr$year +1`; #变量运算,使用expr或let9echo$year10year="olympic'"$year #字符串直接连接,不需要连接符11echo$year1213#usage ofifstatement14if[ $year =1999]15the...
Introduction to the Bash If Statement What is the syntax of a Bash If Statement? What are the double Parentheses ((…)), single […], and double [[..]] Square Brackets? What are the Bash Conditional Expressions? How to use an If Statement with Then, Else, Else If (elif) clauses?
Check to see if a variable is empty or not Create a new bash file, named, and enter the script below. The script above stores the first command-line argument in a variable and then tests the argument in the next statement. This script will print the first argument because it is not em...
Incorrect use of a test operator in a Conditional Statement like using -z instead of -n in a if condition Incorrect use of an Arithmetic operator like multiplying instead of diving a number Incorrect condition to exit from a Bash Loop like when using a while loop instead of an until loop ...
do_something_commands # print to screen or file or do nothing Taking input in a script and making sure there's only one parameter, I have the prompt for input, the read command after, the grep commands. Everything works fine, I just need to implement an if statement I...
STATEMENT1 ... done 循环次数:为列表中的元素的个数; LIST:列表,包含至少一个元素的字符串集合; (1) 直接给出; (2) 数值列表:a){start..end},例如:{1..10} b) seq [start [step]] end (3) 返回列表的命令; (4) globbing; (5) 变量引用:$*, $@ ...
# Note: The exit status may not be the same as with an if statement [[ $var == hello ]] && echo hi # Multi line (no else) [[ $var == hello ]] && { echo hi # ... } case设置变量的简单语句 在:内置的可以用来避免重复variable=在一个case语句。该$_变量存储的最后一个命令的最后...