Shell programming for Linux systems-the normal form

Shell programming is in the form of:

1: meta-character []. *  ?

+ ( )  | {  }  ^  $

2: [a-z0-9] Represents a random number and letter match

3: [^a-z] matches the random one except the letter

4:ab+c + represents a character that matches one or more of the preceding + numbers

5:ab*c * indicates that no or more characters are preceded by the * number

6:ab?c? Represents a match? Character preceding the number

7: (AB) {2}c represents a character that matches two ab characters.

8: (AB) *c (AB) +c (AB)? c the same rules as 4,5,6, just the characters that match all the brackets in the face.

9:^ab matches characters that begin with AB. and [^ab] means that the match except for the character AB

: \<title\> only matches the word title, with a space or newline as the delimiter

fgrep grep egrep command grep in Linux (global regular expression and printing)

The fgrep command does not use the regular form. Match all characters as normal characters at the time of lookup

The grep command supports only normal, regular forms, and does not support the extended regular

The EGREP command supports all extended regularization forms.

Several common ways to use grep:

1:grep-v matches characters not included in the regular table grep-v ' ^ab '/etc/passwd characters that do not start with AB

2:grep--color to mark the matching characters in color

3:grep-o only displays matching characters after filtering.

4:GREP-A2 ' abc '/etc/passwd displays the matching characters and the top two lines of the matching word lines

5:GREP-B2 ' abc '/etc/passwd displays the matching characters and the following two lines of the matching word lines

6:GREP-C3 ' abc '/etc/passwd displays the following and two lines of matching characters and matching word lines

                                                     7:  grep -f/etc/shadow/etc/passwd   includes

in matching/etc/passwd based on content in the/etc/shadow file

                                                                          characters in/etc/shadow

8:GREP-E indicates support for extending the normal form. Equivalent to Egrep

9:

Shell programming for Linux systems-the normal form