Flavor Of Regular Expression
2018-04-05
POSIX
It’s POSIX specification for regular expression in UNIX-like environment tools,such as vim,sed,awk,grep.
BRE
|Metacharacters|Meaning|
|:–|:–|
|.
|match any one character|
|\\
|escape character|
|[
||
|^
|anchor for start of characters,complement set in backet expression|
|$
|anchor for end of characters|
|*
||
note:in GNU implement,you can use ERE special metacharacters by \\
.
BRE tools:sed,grep
ERE
|Metacharacters|Meaning|
|:–|:–|
|(
||
|)
||
|{
||
|}
||
|+
||
|?
||
|\|
||
note:ERE include all BRE metachatacters. ERE tools:awk,egrep,sed -E
POSIT character class
example: [:digit:]
PCRE
PCRE include all ERE metacharacters. PCRE used in most common program language.