Shulou(Shulou.com)06/01 Report--

Regular expression metacharacters:

. Match any single character

*: match the preceding characters any number of times

? Match the preceding characters once or 0 times

\ {mdirection n\}: match the preceding characters at least m times and n times at most

Position Anchor:

^: anchor the beginning of the line, and the content after this character must appear at the beginning of the line

$: anchor the end of the line, and the content after this character must appear at the end of the line

^ $: blank line

\

The content after it must appear as the end of the word

[]: any character in the specified range. Egrep [q,w] / tmp/test

Regular expression of extension:

. Match any single character

*: match the preceding characters any number of times

? Match the preceding characters once or 0 times

+: match the preceding characters at least once

{m,n}:

C | Cat! = c | (Cat)

Example: ifconfig | egrep-o "(\\.) {3}\" you can get all the IP

Integer judgment

-eq equals

-ne is not equal to

-gt is greater than

-ge greater than or equal to

-lt less than

-le is less than or equal to

Document judgment

-e: whether the file exists

-f: test whether the file is a normal file

-d: test whether it is a directory

-r

-w read and write execution is for the current user

-x

String test

=, =: [string1 = string2] or [string1 = = string2]

! =: test whether two strings are not equal to

-n string: tests whether the specified string is empty

-z string: tests whether the specified string is not empty

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