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...
The script above stores the first command-line argument in a variable and then tests the argument in the next statement. This script will print the first argument because it is not empty. However, the output would be “First argument is empty” if nothing is contained in the argument. How ...
echo "The first or second number is empty." else #Calculate the sum sum=$(($n1+$n2)) #Print the summation value echo "The sum of $n1 and $n2 is $sum." fi Output: The following output appears if the script is executed without any argument: The following output appears if the scri...
$ ./checkarg'''./checkarg: line5:1: A non-empty argument is required $ ./checkarg x''./checkarg: line5:2: Two non-empty arguments are required $ ./checkarg x x Thank you. (5) ${#var}: 变量内容的长度 readpasswdif[ ${#passwd} -lt8]thenprintf"Password is too short: %d c...
How to check if a directory exists? How to check if a command succeeds or failed? How to do string comparison and check if a string equals to a value? How to check if a string is in an array? How to use the Bash ternary operator? How to negate an if condition in a Bash if sta...
By using the -e option, shuf would treat each argument as a separate input line. Do not forget to use the double-quote otherwise elements with whitespaces will be split. Once the array is shuffled we can reassign its new value to the same variable....
Example-3: Check the variable is empty or not Create a bash file named “check_var3.sh” and add the following script. The script will store the first command-line argument into a variable,$argvthat is tested in the next statement. The output will be “First argument is empty” if no...
} while (0)/* If there is no search string, try to use the previous search string, if one exists. If not, fail immediately. */if(*temp =='\0'&& substring_okay) {if(search_string) {free(temp); temp = savestring (search_string); ...
elif [ -d $file ]; then echo "$file is a directory." else echo "$file does not exist" fi I improved the script a little by adding a check on number of arguments. If there are no arguments or more than one argument, the script will output a message and exit without running rest...
# stdin replaced with a file supplied as a first argument exec < $1 let count=0 while read LINE; do ARRAY[$count]=$LINE ((count++)) done echo Number of elements: ${#ARRAY[@]} # echo array's content echo ${ARRAY[@]} # restore stdin from filedescriptor 10 ...