-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 ...
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...
Afterdeclaring a string variable, use the-zoperator in anif statementto check whether a string is empty or not: MY_STRING="" if [ -z $MYSTRING ] then echo "String is empty" else echo "String is not empty" fi For more Shell scripting tips,check out or Bash/Shell scripting articles!
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" ...
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 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...
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...
is readable-s FILE_NAM # TrueifFILE_NAM existsandisnotempty-w FILE_NAM # TrueifFILE_NAM has write permission-x FILE_NAM # TrueifFILE_NAM is executable#字符串测试操作-z STRING # TrueifSTRING is empty-n STRING # TrueifSTRING isnotemptySTRING1...
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 int1 -gt int2 若int1大于int2,则为真 ...
$ nano ifnot.sh Example 1 Within the first Bash example of this article, we will be using the “if-not” operator to check which one of the two strings is less than the other. For this, we have added the Bash support within the file and added two new string variables v1 and v2...