1-18
z
Input the keyword
begin
,
exclude
, or
include
as well as the regular expression at the command
line to filter the output information.
z
Input slash (/), minus (-), or plus (+) as well as the regular expression to filter the rest output
information. Slash (/) is equal to the keyword
begin
, minus (-) is equal to the keyword
exclude
, and
plus (+) is equal to the keyword
include
.
Keywords
begin
,
exclude
, and
include
have the following meanings:
z
begin
: Displays the line that matches the regular expression and all the subsequent lines.
z
exclude
: Displays the lines that do not match the regular expression.
z
include
: Displays only the lines that match the regular expression.
The regular expression is a string of 1 to 256 characters, case sensitive. It also supports special
characters as shown in
Table 1-5
.
Table 1-5
Special characters in a regular expression
Character
Meaning
Remarks
^
string
Starting sign,
string
appears only at the
beginning of a line.
For example, regular expression “^user”
only matches a string beginning with
“user”, not “Auser”.
string
$
Ending sign,
string
appears only at the
end of a line.
For example, regular expression "user$”
only matches a string ending with “user”,
not “userA”.
.
Full stop, a wildcard used in place of any
character, including single character,
special character and blank.
For example, “.l” can match “vlan” or
“mpls”.
*
Asterisk, used to match a character or
character group before it zero or multiple
times.
For example, “zo*” can match “z” and
“zoo”; (zo)* can match “zo” and “zozo”.
+
Addition, used to match a character or
character group one or multiple times
before it
For example, “zo+” can match “zo” and
“zoo”, but not “z”.
|
Vertical bar, used to match the whole
string on the left or right of it
For example, “def|int” can only match a
character string containing “def” or “int”.
_
Underline. If it is at the beginning or the
end of a regular expression, it equals ^ or
$; in other cases, it equals comma,
space, round bracket, or curly bracket.
For example, “a_b” can match “a b” or
“a(b”; “_ab” can only match a line
starting with “ab”; “ab_” can only match a
line ending with “ab”.
-
Hyphen. It connects two values (the
smaller one before it and the bigger one
after it) to indicate a range together with
[ ].
For example, “1-9” means numbers from
1 to 9 (inclusive); “a-h” means from a to h
(inclusive).
[ ]
A range of characters, Matches any
character in the specified range.
For example, [16A] can match a string
containing any character among 1, 6,
and A; [1-36A] can match a string
containing any character among 1, 2, 3,
6, and A (with - being a hyphen).
“]” can be matched only when it is put at
the beginning of [ ] if it is used as a
common character in [ ], for example
[ ]
string
]. There is no such limit on “[”.
