= operators are used, the string to the right of the operator is considered a pattern and matched according to the rules described below under Pattern Matching. The return value is 0 if the string matches or does not match the pattern, respectively, and 1 otherwise. Any part of the pattern...
the string matching the entire regular expression. The element of BASH_REMATCH with index n is the por- tion of the string matching the nth parenthesized subexpression. 在Bash中二元操作符 =~ 进行扩展的正则表达式匹配。如果匹配,返回值为0,否则1,如果正则表达式错误,返回2。如果shell选项nocasematch没...
string1 == string2如果所给的两个字符串相等,返回 true,否则返回 false string1 != string2如果所给的两个字符串不相等,返回 true,否则返回 false string1 < string2如果string1字符串在词典上的顺序早于string2字符串,返回 true,否则返回 false string1 > string2如果string1字符串在词典上的顺序晚于string2...
操作符时,操作符右边的字符串被认为是一个模式,根 据下面 Pattern Matching(模式匹配) 章节中的规则进行匹配。如果匹配 则返回值是 0,否则返回 1。模式的任何部分可以被引用,强制使它作为 一个字符串而被匹配。 表达式可以用下列操作符结合起来。根据优先级的降序列出如下: ( expression ) 返回表达式 expression ...
tion of the string matching the nth parenthesized subexpression. 在Bash 中二元操作符 =~ 进行扩展的正则表达式匹配。如果匹配,返回值为 0, 否则1,如果正则表达式错误,返回2。如果shell 选项nocasematch 没有开启, 那么匹配时 区分大小写。在正则表达式中小括号包围的子表达式的匹配结果保 存在BASH_REMATCH ...
This expansion modifies the case of alphabetic characters in parameter. The pattern is expanded to produce a pattern just as in pathname expansion. The ^ operator converts lowercase letters matching pattern to uppercase; the , operator converts matching uppercase letters to lowercase. ...
3. Pattern Matching and Substitution 3.1. Length We can access the length of a string using the hash (#) operator inside parameter expansion before the variable name: $ NAME=Baeldung $ echo ${#NAME} 8 3.2. Substrings We can extract a substring using the colon (:) operator inside the pa...
The next type of string operator is used to match portions of a variable’s string value against patterns. Patterns, as we saw in Chapter 1, are strings that can contain wildcard characters (*, ?, and [] for character sets and ranges). Table 4-2 lists bash’s pattern-matching ...
${1%%"$2"*}表示将将子串匹配后的所以字符全部删除,保留之前未匹配部分。有兴趣的伙伴可以利用man bash,查看“${parameter%%word}”的解释(“Remove matching suffix pattern”)。(感受下“A="hello"; echo "${A%%ll*}"”这条命令) 然后返回剩余部分的字符串的长度,这样变相知道了整个子串的偏移位置 ...
-o, --only-matching Show only the part of a matching line that matches PATTERN. [root@jfht ~]#echo "$STR" | grep -o "[^ ]\+\( \+[^ ]\+\)*" any string 使用expr match去除前后的空白 错误:expr match "$STR" "[[:space:]]*\(.*\)[[:space:]]*" ...