在bash中,我们可以使用if语句结合条件判断来判断一个变量是否为空。具体的语法如下: ```bash if [ -z "$var" ]; then echo "Variable is empty" else echo "Variable is not empty" fi ``` 在上面的示例中,-z表示判断变量是否为空,$var是我们要判断的变量。如果变量var为空,则输出“Variable is empty...
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...
echo 'not enough disk space' fi 注意,if [ check_space ]并没有做你认为它做的事情:函数check_space根本不会被调用。check_space只是test([)命令的字符串。[ string ]检查字符串的长度:如果字符串为non-empty,则返回true,否则返回false。 您还可以考虑将路径和大小作为参数传递给函数: #!/bin/bash check_...
bash command if a string is not empty examples of the check when DiskInternals can help you Are you ready? Let's read! Variables that are set and not empty A variable is either defined or not defined. However, when a variable is defined but has no value, then the variable is “Not ...
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
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 "$1"]; then ...
If -F is given, shell-command is not executed but considered success if neither empty nor zero (after formats are expanded). Note that tmux shell-command expansion will expand variables of the form #{pane_current_path} but otherwise will leave the command alone. More impo...
bash的if grep语句与 bash的基础特性: bash中的变量的种类: 根据变量的生效范围等标准: 本地变量:生效范围为当前shell进程:只对当前shell进程有效,当前shell的子shell进程均无效 环境变量:生效范围为当前shell进程及其子进程,对其他shell无效(定义:declare -x) ...
TestFile1 does not exist or is empty. 向文件添加一些内容,然后再测试一次: [student@studentvm1 testdir]$ 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 test -z "not empty";then echo "YES"; else echo "NO"; fiNO $ if test -z "";then echo "YES"; else echo "NO"; fiYES $ if test -n "";then echo "YES"; else echo "NO"; fiNO 文件测试 $ if test -f /bin/bash; then echo "YES"; else echo "NO"; fiYES ...