#!/bin/bash # if [ $# -ge 1 ]; then if ! id $1 &>/dev/null;then useradd $1 fi fi 1. 2. 3. 4. 5. 6. 7. 方法二: #!/bin/bash if !id $1 & >> null;then useradd $1 else echo "the user exists" fiif可以嵌套: if CONDITION1; then if CONDITION2; then CMD fi fi...
DIRECTORY=$1if["`ls -A$DIRECTORY`"=""]thenecho"$DIRECTORYis indeed empty"elseecho"$DIRECTORYis not empty"fi shell中[ ]和[[]]的区别 探索shell中[ ]和[[]]的区别_chen1415886044的博客-CSDN博客 多数情况下[ ]和[[]]是可以通用的,单中括号 [ ],bash 的内部命令,[和test是等同的。双中括号[...
以下是一个简单的Bash脚本示例,使用if语句判断一个文件是否存在: bash #!/bin/bash file="example.txt" if [ -e "$file" ]; then echo "File $file exists." else echo "File $file does not exist." fi 4. Bash if语句中的逻辑运算符 Bash中的逻辑运算符包括: &&:逻辑与,例如[ "$...
#!/bin/bash if test –d ~/tmp then echo “the directory already exists” else mkdir ~/tmp fi 试说明该代码段主要实现了什么功能?相关知识点: 试题来源: 解析 答:该代码段主要实现的功能为:判断用户主目录下的子目录tmp是否存在,并根据判断结果做出如下处理: 存在: 显示“the directory already exists”...
How do I check if a directory exists in a Bash shell script?, A directory won't mind the extra slash. A file will evaluate to false. Empty will remain empty, so false. And a symlink will be resolved to its destination. Of course, it depends on your goal. If you want to go there...
/bin/bash directory="/path/to/directory" if [ -d "$directory" ]; then echo "$directory exists." else echo "$directory does not exist." fi ``` 在上述示例中,我们定义了一个变量`directory`,并赋值为指定目录的路径。然后使用`-d`参数判断目录是否存在,如果目录存在,则输出`$directory exists.`...
How to check if a directory exists? How to check if a command succeeds or failed? How to do string comparison and check if a string equals to a value? 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 sta...
“`bash if test -f “file.txt”; then echo “file.txt 存在” fi “` 2. 文件检查命令:除了test命令,还有一些特定的命令用于检查文件属性。常见的文件检查命令包括: –-e:检查文件是否存在 –-d:检查是否为目录 –-f:检查是否为普通文件 –-r:检查是否可读 ...
/bin/bash #!/bin/bash FILE=$HOME/simple.txt if [ -f '$FILE' ] then echo '$FILE exists' else echo '$FILE doesn't exist' fi 答案4:检查给定字符串是否为空 编写shell脚本,提示用户输入一个字符串,然后检查输入的字符串是否为空。 #!/bin/bash...
How do I check if a directory exists in a Bash shell script?, To check if a directory exists: if [ -d "$DIRECTORY" ]; then echo "$DIRECTORY does exist." fi. To check if a directory does not exist: if [ ! Implementing a Unix shell in C: check if file is executable ...