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!
str - the String to check, may be null Returns: true if the String is empty or null isNotEmpty public static boolean isNotEmpty(String str) Checks if a String is not empty ("") and not null. StringUtils.isNotEmpty(null) = false StringUtils.isNotEmpty("") = false StringUtils.isNotE...
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 ...
# remove the last character in string and return it in $rval if [ -z "$1" ]; then # empty string rval="" return fi # wc puts some space behind the output this is why we need sed: numofchar=`echo -n "$1" | wc -c | sed 's/ //g' ` if [ "$numofchar" = "1" ]...
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...
echo "INT is empty." >&2 exit 1 fi if [ $INT -eq 0 ]; then echo "INT is zero." else if [ $INT -lt 0 ]; then echo "INT is negative." else echo "INT is positive." fi if [ $((INT % 2)) -eq 0 ]; then echo "INT is even." else echo "INT is odd." fi fi上面...
A null or empty ("") String will return false. StringUtils.contains(null, *) = false StringUtils.contains("", *) = false StringUtils.contains("abc", 'a') = true StringUtils.contains("abc", 'z') = false Parameters: str - the String to check, may be null ...
# empty string rval="" return fi # wc puts some space behind the output this is why we need sed: numofchar=`echo -n "$1" | wc -c | sed 's/ //g' ` if [ "$numofchar" = "1" ]; then # only one char in string
值并发生重复赋值时,bash会覆盖该键。这 允许我们有效地删除数组重复。 CAVEAT:需要bash4+ 示例功能: remove_array_dups() { # Usage: remove_array_dups "array" declare -A tmp_array for i in "$@"; do [[ $i ]] && IFS=" " tmp_array["${i:- }"]=1 ...
The -n and -z will also check for a string length. The -n option check for a non-zero length and the -z option check for a zero-length string. Those primaries may be useful if you intend is to check if a variable is empty or not. Though be careful if your shell script runs wi...