if [[ -z $String ]]; then echo "The variable String is an empty string." fi 输出: The variable String is an empty string. 在这个程序中,string 是一个空变量。由于 -z 运算符返回 true,如果 string 的长度是 0,因此我们得到 The variable String is an empty string. 作为给定程序的输出。 St...
and we have initialized a string variable “v” with the value “Hello” in it. Then, we started the “if-else” statement to check whether the string is empty. For this, we have used the “-z” option within the square brackets...
Sometimes, it is required to check if a string variable is non-empty or if it contains a string value more than zero length. There are many options in Bash to do this task. Using the “-n” option with the “if” statement is one of the ways to check whether a variable is non-em...
Test if string has non whitespace characters in Bash, The backquotes execute the command within; bash line parsing convert tabs and newlines to blanks and joins double blanks. The echo command re-emits this string, which is shrunk to an empty string for the final test by [[ ]]. I think...
if [ -z "$variable"]; then echo "The variable is empty." else echo "The variable is not empty." fi OUTPUT 1 2 3 The variable is empty. Now, assign any value as demonstrated below. Again, you can set any value: a string, integer, or float value. Use -z Option 1 2 3...
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 ...
STRING Trueifstring is not empty. 即,test命令使用-z STRING操作符来判断STRING字符串的长度是否为 0。 如果为 0,就是空字符串,会返回 true。 具体写法是test -z STRING,使用[命令则写为[ -z STRING ]。 -n STRING操作符判断STRING字符串的长度是否为 0。
string1 = string2 若两个字符串相等,则为真 string1 != string2 若两个字符串不相等,则为真 int1 -eq int2 若int1等于int2,则为真 int1 -ne int2 若int1不等于int2,则为真 int1 -lt int2 若int1小于int2,则为真 int1 -le int2 若int1小于等于int2,则为真 ...
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 [ $count -gt 0 ] then echo "Count is positive." else echo "Count is zero or negative." fi Example 2: String Comparison !/bin/bash name="Alice" if [ "$name" == "Alice" ] then echo "Hello, Alice!" else echo "You are not Alice." ...