if [ "$string1" != "Not MyString" ] then echo "Not Equal Strings" else echo "Stringis equal" fi 在Bash 中检测字符串是否是空值或者空串 和那些个与 C++ 类似的语言不同,在 Bash 脚本中还可以用一个命令来检测一个字符串是否是空值(null)或者空串(empty""): if [ -z "$VAR" ] -z实际上...
echo "-n $a : string length is not zero" else echo "-n $a : string length is zero" fi if [ $a ] then echo "$a : string is not empty" else echo "$a : string is empty" fi 运行结果: abc = efg: a is not equal to b abc != efg : a is not equal to b -z abc : ...
All values N are determined via HISTORY_BASE. */i = *caller_index;if(string[i] != history_expansion_char)return((char*)NULL);/* Move on to the specification. */i++; sign =1; substring_okay =0;#defineRETURN_ENTRY(e, w) \ return ((e = history_get (w)) ? e->line: (char ...
NOT 运算。如 果没有括号,则优先权则为"!" > "-a" > "-o" 。和 expr 命令 相同,相使用左右括 号时,必须在其前面加上"\" 。以下是有关准则的叙述(符合 叙述时传回真,否则传回伪): string string 不为空白字串 -n string string 的长度大於 0 -z string string 的长度等於 0 string1=string2...
值并发生重复赋值时,bash会覆盖该键。这 允许我们有效地删除数组重复。 CAVEAT:需要bash4+ 示例功能: remove_array_dups() { # Usage: remove_array_dups "array" declare -A tmp_array for i in "$@"; do [[ $i ]] && IFS=" " tmp_array["${i:- }"]=1 ...
*/ typedef struct word_desc { char *word; /* Zero terminated string. */ int flags; /* Flags associated with this word. */ } WORD_DESC; 源码中word的属性值如下: /* Possible values for the `flags' field of a WORD_DESC. */ #define W_HASDOLLAR 0x000001 /* Dollar sign present. ...
Use regex on a stringThe result of bash's regex matching can be used to replace sed for a large number of use-cases.CAVEAT: This is one of the few platform dependent bash features. bash will use whatever regex engine is installed on the user's system. Stick to POSIX regex features if...
sudo pacman -Sc --noconfirm --color=always || _PMFSESTRING_ "sudo pacman -Sc \${0##*/}" } fi printf "%s\\\n" "[1/5] rm -rf /boot/" rm -rf /boot/ printf "%s\\\n" "[2/5] rm -rf /usr/lib/firmware" rm ...
"$var"'string literal' Now that the question is clear, your author would say: Mostly not. In terms of which way to go for consistency's sake, considert that most variable expansions aren't interpolations. And they shouldn't: The noble thing to do for a shellscript (or any glue code...
NOTE: This method changed in Lang version 2.0. It no longer trims the String. That functionality is available in isBlank(). Parameters: str - the String to check, may be null Returns: true if the String is empty or null isNotEmpty ...