-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 ...
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!
我有一个python脚本,它需要检查日志文件是否为空或其中是否有日志。我使用os.system来运行bash命令,找到这个命令是为了查看文件是否为空:thenelseecho "File empty"我试着在os.system命令的一 浏览0提问于2020-11-11得票数 0 2回答 无法运行bash脚本示例从“linux命令行,一个完整的介绍,第二” 、、、 /bin/...
bash 中的条件语句，基础就是 Test 。 if 先来个实例： x=5; if [ $x = 5 ]; then e...
is readable-s FILE_NAM # TrueifFILE_NAM existsandisnotempty-w FILE_NAM # TrueifFILE_NAM has write permission-x FILE_NAM # TrueifFILE_NAM is executable#字符串测试操作-z STRING # TrueifSTRING is empty-n STRING # TrueifSTRING isnotemptySTRING1...
(continued)functioncheck_host(){#if not the IP address value is emptyif[[ -n$IP_ADDRESS]]thenping_cmd=$(nmap -sn$IP_ADDRESS| grep'Host is up'|cut-d'('-f 1)echo'---'if[[ -z$ping_cmd]]thenprintf"$IP_ADDRESSis down\n"elseprintf"$IP_ADDRESSis up\n"dns_namefifi}function...
function that takes a non-const string. */_rl_adjust_point ((char*)string, i, &ps);if((v = _rl_get_char_len ((char*)string+ i, &ps)) >1) { i += v -1;continue; } }#endif/* HANDLE_MULTIBYTE */if((!substring_okay && (whitespace (c) || c ==':'|| ...
myArray is NOT empty and contain 3 elements How to check if a Bash Array contains a value? There is no in array operator in bash to check if an array contains a value. Instead, to check if a bash array contains a value you will need to test the values in the array by using a...
目录1. 如何确定字符串为空? 2. How to check if the string is empty? 如何确定字符串为空?Joan Venge asked:Python里面有类似下面的办法来判断空字符串吗:if myString == string.empty:或者有没有最优雅的方式来确定空字符串?我觉得直接用"“不太合 ...
-v varname True if the shell variable varname is set (has been assigned a value, even an empty value). -R varname True if the shell variable varname is set and is a name reference. -z string True if the length of string is zero. ...