if[ ! -z"$variable"];thenecho"Variable is not empty"elseecho"Variable is empty"fi 在这个示例中,$variable是要检查的变量。如果它不为空,则打印"Variable is not empty";否则,打印"Variable is empty"。 使用条件表达式检查变量是否为空 除了if 语句,还可以使用条件表达式来检查变量是否为空。条件表达式可...
-z is the second supported bash string comparison operator used to check if a string is empty or not. The -z operator functions similarly like -n operator. Below is an example: Most importantly, you should add spaces around the square brackets. If there are no spaces, bash will complain ...
/bin/bash function empty_string() {iftest -n $1; then echo'(1) -n $1 :' "No quote: not empty."fiif[ -z $1]; then echo'(2) -z $1 :' "No quote: empty."fiiftest -n "$1"; then echo'(3) -n "$1":' "Quote : not empty."fiif[ -z "$1"]; then echo'(4) -z...
/bin/bashfunctionempty_string() {iftest-n$1;thenecho'(1) -n $1 :'"No quote: not empty."fiif[ -z$1];thenecho'(2) -z $1 :'"No quote: empty."fiiftest-n"$1";thenecho'(3) -n "$1":'"Quote : not empty."fiif[ -z"$1"];thenecho'(4) -z "$1":'"Quote : empty."...
TestFile1 does not exist or is empty. 向文件添加一些内容,然后再测试一次: [student@studentvm1 testdir]$ File="TestFile1" ; echo "This is file $File" > $File ; if [ -s $File ] ; then echo "$File exists and contains data." ; else echo "$File does not exist or is empty." ...
If [ ! -s 1] ;then Yes | rm 1 Else Echo “the file is not empty!” Fi Exit 0 执行:./x.sh t.txt(t存在且不空)功能是:___ 相关知识点: 试题来源: 解析 判断文件 .txt 是否为空 反馈 收藏
bash的if grep语句与 bash if and bash的基础特性: bash中的变量的种类: 根据变量的生效范围等标准: 本地变量:生效范围为当前shell进程:只对当前shell进程有效,当前shell的子shell进程均无效 环境变量:生效范围为当前shell进程及其子进程,对其他shell无效(定义:declare -x)...
print_dir_if_not_empty() { local dir=$1 is_empty $dir && \ echo "dir is empty" || \ echo "dir=$dir" } 好的例子:我们可以清晰看到行和连接符号之间的联系。 print_dir_if_not_empty() { local dir=$1 is_empty $dir \ && echo "dir is empty" \ ...
if [ -s $File ] then echo "$File exists and contains data." elif [ -e $File ] then echo "$File exists and is empty." else echo "$File does not exist." fi 图表2: 像在脚本里一样重写书写命令行程序 对于大多数 CLI 程序来说,让这些复杂的命令变得有逻辑需要写很长的代码。虽然 CLI ...
If you want to delete a subdirectory named orders that isn't empty, you can use the rm command this way:Bash Copy rm -r orders This deletes the orders subdirectory and everything in it, including other subdirectories.cp commandThe cp command copies not just files, but entire directories...