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 ...
Checks if a String is not empty ("") and not null. StringUtils.isNotEmpty(null) = false StringUtils.isNotEmpty("") = false StringUtils.isNotEmpty(" ") = true StringUtils.isNotEmpty("bob") = true StringUtils.isNotEmpty(" bob ") = true Parameters: str - the String to check, may ...
Check if the string is not empty The-nflag checks if the string length is non-zero. It returns true if the string is non-empty, else it returns false if the string is empty: $ [ -n "sam" ] && echo "True" || echo "False" Check if the string is empty The-zflag checks whethe...
Here is another option, “-n”, to check whether the specified string is empty or not. It works on the rule of checking the length of a string by counting the string characters in it. If the length of a particular string turns out to be other than zero, it will return “true”; o...
if [ ${#array1[@]} -eq 0 ]; then This time, we got the size of the array and test it with the number zero. Let's see both methods with sample examples. Check empty bash array with string comparison We are going to use two elements to check if bash array is empty or not. On...
In both examples, we used the if statement with the -z option to check if the variable is empty. Here, the -z option is a unary test operator that checks if the string is empty. This operator accepts one argument that is a string to be tested; it returns true (0 exist status) if...
In this example, the substitution command is used with $() to capture the output of grep, and then the -z option of the test command is used to check if the resulting string is empty or not. Here, the grep command searches for the pattern pattern in the file dummy.txt. The output...
代码语言:txt 复制 str="" if [ "$str" == "" ]; then echo "String is empty" else echo "String is not empty" fi 字符串长度比较:可以使用大于号(>)、小于号(<)来比较两个字符串的长度。例如: 代码语言:txt 复制 str1="Hello" str2="World" if [ ${#str1} -gt ${#str2} ]; the...
Using the “If -N” Statement 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 che...
I would like to check if a string begins with "node" e.g. "node001". Something likeif [ $HOST == node* ] then echo yes fi How can I do it correctly?I further need to combine expressions to check if HOST is either "user1" or begins with "node":...