= STRIN2 # Trueifstrings arenotequal#算术测试操作var1 -eq var2 # Trueifvar1 is equal to var2var1 -ne var2 # Trueifvar1notequal to var2var1 -lt var2 # Trueifvar1 is less than var2var1 -le var2 # Trueifvar1 is less thanorequal ...
exit 0 1 2 ~ script % ./if.sh 109 greater than 11 -eq:equal 等于-lt:less than 小于-gt:greater than 大于-le:less than or equal 小于或等于-ge:greater than or equal 大于或等于 为什么不可以用<,>等来表达上面这些关系,因为这些符号在类Unix系统中有特殊用途。Jack...
count is equal to 3 count is equal to 2 count is equal to 1 在WHILE之前,count变量设置为3,但每次执行WHILE循环时,count的值都会减去1。然后循环再次从顶部开始,并重新检查条件表达式,看它是否仍然等效于true。经过三次迭代后,循环计数等于0,因为每次迭代的计数都会减去1。因此,逻辑表达式[[ $count...
如果你有过POSIX编程经验(比如Linux下C编程),你会知道一个errno的东西。你也会知道大量的if语句用来测试一个函数的调用结果,每个函数基本上都是返回0时表示操作成功,而如果返回非0则出错,此时你也要exit(0)。 下面言归正传 测试整数 基本规则 整数的test就是大小关系的比较,与其他语言不同,Bash中没有使用<,>来...
How to check if a string is in an array? How to use the Bash ternary operator? How to negate an if condition in a Bash if statement? (if not command or if not equal) How to use the BASH_REMATCH variable with the Regular Expression Operator =~?
Code:#!/bin/bash # File to check file_to_check="temp.txt" # Check if file exists if [ -e "$file_to_check" ]; then echo "File exists" exit 0 # Exit with code 0 indicating success else echo "File not found" exit 1 # Exit with code 1 indicating failure fi CopyOutput:...
if [ $? -eq 0 ]; then ... else ... fi: This construct checks the exit status of the previous command. If the exit status is 0 (indicating success), it prints a success message; otherwise, it prints a failure message. 6.
count=0 while IFS= read -r _; do ((count++)) done < "$1" printf '%s\n' "$count" } 1. 2. 3. 4. 5. 6. 7. 8. 用法示例: $ lines ~/.bashrc 48 $ lines_loop ~/.bashrc 48 1. 2. 3. 4. 5. 计算目录中的文件或目录 ...
If the exit status code is not equal to zero, an error message is printed. Otherwise, a success message is printed.#!/bin/bash #Take a Linux command name echo -n "Enter a command: " read cmd_name #Run the command $cmd_name #Check whether the command is valid or invalid if [ ...
i=0 while [ $i -lt 5 ] do i=$(( $i+1 )) if [ $i -eq 2 ] then continue fi echo $i done In the above script, anifcondition is specified to tell the program tocontinueandresetthe loop if variableiis equal to 2. Bash while Loop break Statement ...