echo "a + b : $val" val=`expr $a - $b` echo "a - b : $val" val=`expr $a \* $b` echo "a * b : $val" val=`expr $b / $a` echo "b / a : $val" val=`expr $b % $a` echo "b % a : $val" if [ $a == $b ] then echo "a == b" fi if [ $a !=...
21[ -S FILE ] 如果 FILE 存在且是一个套接字则为真。22[ FILE1 -nt FILE2 ] 如果 FILE1 has been changedmorerecently than FILE2, or 如果 FILE1 exists and FILE2 does not则为真。23[ FILE1 -ot FILE2 ] 如果 FILE1 比 FILE2 要老, 或者 FILE2 存在且 FILE1 不存在则为真。24[ FILE1...
file=$1if[-e $file]then echo-e"File $file exists"elseecho-e"File $file doesnt exists"fi $./exist.sh/usr/bin/boot.ini File/usr/bin/boot.ini exists 请参阅之前的文章以了解各种bash if 语句类型。 Bash 示例 2. 比较数字 下面的脚本从用户那里读取两个整数,并检查这两个数字是否相等或大于或...
When bash is invoked as an interactive login shell, or as a non-interactive shell with the –login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in...
# Check if a file exists if [ -f $file ] then echo "File exists" else echo "File does not exist" fi # Check if a command is successful if ls then echo "Command succeeded" else echo "Command failed" fi ``` 通过使用if-else语句,用户可以根据不同的条件执行不同的操作。这使得Bash脚本...
#!/bin/bash if [ -z $1 ];then echo "you entered nothing" exit 1 else if [ -e $1 ]; then echo "the file exists" else echo "the file doesn't exist" fi fi 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 练习13:写一个脚本,传递一个文件路径参数给脚本 (1) 如果脚本无参数,则...
This is the job of the test command, which can check if a file exists and its type. Since only the check is completed, the test command sets the exit code to 0 or 1 (either false or true, respectively) whether the test is successful or not. ...
The result of bash's regex matching can be used to replace sed for a large number of use-cases.CAVEAT: This is one of the few platform dependent bash features. bash will use whatever regex engine is installed on the user's system. Stick to POSIX regex features if aiming for ...
[student@studentvm1 testdir]$ touch TestFile1 在这个简短的 CLI 程序中,修改$File变量的值相比于在多个地方修改表示文件名的字符串的值要容易: [student@studentvm1 testdir]$ File="TestFile1" ; if [ -e $File ] ; then echo "The file $File exists." ; else echo "The file $File does not...
Python，perl，C++ bash:脚本解释器 编程能力： 脚本编程 变量：内存空间，命名的内存空间（可以...