Regex Syntax: Egrep Patterns
The escape character is a backslash (\
). You can use it to escape metacharacters to
use them in their plain character form.
In the following examples, literal E
and F
denote any expression, whether a pattern or a character:
(
Start a capturing
subexpression.
)
End a capturing
subexpression.
E
|F
Disjunction, match either
E
orF
(inclusive).E
is preferred if both match.E*
Act as Kleene star, match
E
zero or more times.E+
Closure, match
E
one or more times.E?
Option, match
E
optionally once.
.
Match any character except
for newline characters (\n
, \f
, \r
) and
the NULL byte.
E{
n
}
Match
E
exactlyn
times.E{
n
,}
orE{
n
,0}
Match
E
n
or more times.E{,
n
}
orE{0,
n
}
Match
E
at mostn
times.E{
n
,
m
}
Match
E
no less thann
times and no more thanm
times.
[
Start a character set. See
"Character Sets for Egrep and
ZSH_FILEGLOB.”
$
Match the empty string at the
end of the input or at the end of a line.
^
Match the empty string at the
start of the input or at the beginning of a line.
Escaped Tokens for Regex Syntax Egrep
The following list describes the tokens:
\0
n
..
n
The literal byte with octal value
n
..
n
.\0
The NULL byte.
\[1-9]..
x
The literal byte with decimal value
[1-9]..
x
.\x
n
..
n
or\0x
n
..
n
The literal byte with hexadecimal value
n
..
n
.\<
Match the empty string at the beginning of a word.
\>
Match the empty string at the end of a word.
\b
Match the empty string at a word boundary.
\B
Match the empty string provided it is not at a word boundary.
\w
Match a word-constituent ...
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