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Perl 5 expression
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Description
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.
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Matches exactly one character, regardless of what the character is.
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?
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The preceding item is optional and matched at most once (error if no preceding item).
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*
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The preceding item will be matched zero or more times (error if no preceding item).
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+
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The preceding item will be matched one or more times (error if no preceding item).
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^
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Match at beginning of a line.
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$
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Match at end of a line.
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{n}
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The preceding item is matched exactly n times (error if no preceding item).
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{n, }
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The preceding item is matched n or more times (error if no preceding item).
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{,m}
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The preceding item is optional and is matched at most m times (error if no preceding item).
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{n,m}
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The preceding item is matched at least ntimes, but not more than m times (error if no preceding item).
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[abc]
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Matches the characters a OR b OR c.
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[a-z]
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Matches any character from a to z.
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[^abc]
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Matches any character EXCEPT a, b, or c.
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\d
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Matches exactly one digit.
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\D
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Matches any character EXCEPT a digit.
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\w
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Matches exactly one letter, number, or the underscore character(_).
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\W
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Matches any one character EXCEPT a letter, number, or the underscore character.
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\s
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Matches exactly one character of white space (for example, spaces, tabs, newlines, or any character that would not use ink if printed on a printer).
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\S
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Matches any character that is NOT a white space.
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\
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Dereferences metacharacters (called "quoting").
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Separates two or more choices such as either|or behavior.
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Example
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Description
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^error
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Matches the exact word error only when it appears at the beginning of a line.
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\(9239\)$
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Matches the exact entry (9239) only when it appears at the end of a line.
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da.*e
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Matches the exact words date, daze, database, and dattape. This Perl 5 regular expression, .*, is similar to the wild card * on UNIX.
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abc|abd|abe
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Matches abc, abd, and abe.
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b.d
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Matches bad, bud, and bid, but not bald.
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da.....e
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Matches database and dattape, but not date and daze.
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3.14
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Matches 3.14, 3f14, and 3814.
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3\.14
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Matches 3.14, but not 3f14 and 3814.
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ab?c
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Matches ac and abc.
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ab*c
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Matches ac, abc, abbc, abbbc, and so forth.
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ab+c
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Matches abc, abbc, and so forth, but not ac.
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d\.*z
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Matches dz, d.z, d..z, d...z, and so forth.
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d.\*z
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Matches da*z, db*z, dc*z, and so forth.
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1\.\d\d
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Matches any three-digit floating point number from 1.00 to 1.99******.
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a\Dc
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Matches abc, a&c, and aFc, but not a2c or a8c.
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a\wc
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Matches abc, aGc, and a_c, but not a%c.
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a\Wc
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Matches a%c, a?c, and a c, but not abc, aGc, or a_c.
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a\sc
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Matches any three-character string starting with a and ending with c whose second character is a space, tab, or newline.
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a\Sc
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Matches any three-character string starting with a and ending with c whose second character is not a space, tab, or newline.
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ab{3,5}c
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Matches abbbc, abbbbc, abbbbbc, only.
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.{3,5} pentane
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Matches cyclopentane, neopentane, and isopentane, but not n-pentane.
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a[bc]d
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Matches abd and acd, only.
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a[a-z]c
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Matches any three-character string starting with a and ending with c, and whose second character is any letter from a to z, inclusive.
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