The grep command usage for Shell Scripting Learning notes

grep Basic Usage

grep [Options] [mode] [file:]

Options

-C outputs only the number of matching rows

-I ignore case when searching

-H does not display file names when querying multiple files

-L searches only for matching file names, not specific matching rows

-n Lists all matching rows and displays line numbers

-S does not display error messages that do not exist or have no matching text

-V Displays all lines that do not contain matching text

-W Match Whole word

-X matches an entire row

-R recursive search that not only belongs to the current working directory, but also searches subdirectories

-Q Disables the storage of any results to postpone status indicating whether the owning is successful

-B Prints the offset of the header that matches the leading file, in bytes

-O with the-B option to print the offset of the matched word from the head of the file, in bytes

-E supports extended regular expressions

-F does not support regular expressions, the literal meaning of the installation string is matched

Mode

String

Variable

Regular expressions

1.grep search for files or characters with spaces that need to be enclosed in quotation marks

2.grep You can use wildcards when searching multiple files

grep combined with regular expressions

1. Match the beginning of the line

Example:

grep ^a file finds lines beginning with a in text

Example: grep-c ^$ file Find the number of blank lines in text

Grep-c ^[^$] The number of non-blank lines in the file lookup text

2. Setting case

grep-n [Cc] file case-insensitive lookup of rows with C

Grep-n-I. C file

3. Match repeating characters

grep ^/..../file matches a total of six characters with or ending with any four characters in the middle

grep ^-*b See the beginning of a line with 0 "-" or any "-" matches with B end

4. Escape character

Example 1: Escaping "."

grep www\.example\.com search for rows containing www.example.com

Example 2: Escape "-"

grep ' \-{5\} file

5.POSIX characters

[: Upper:] denotes uppercase [A-z]

[: lower:] = lowercase letter [A-z]

[:d igit:] means number [0-9]

[: Alnum:] denotes uppercase and lowercase letters and numbers [0-9A-Z-A-Z]

[: Space:] Indicates a space or TAB key

[: Alpha:] denotes uppercase and lowercase letters [a-z-a-z]

[: Cntrl:] represents the CTRL key

[: Graph:] or [:p rint:] denotes ASCII 33-126 characters

[: xdigit:] = 16 binary number [0-9a-f-a-f]

Example:

grep ^[[:upper:]] file finds lines beginning with uppercase letters in a line character

POSIX characters need to be enclosed in [].

6. Exact match

grep "\<the\> matches the line containing the word

Must have a quoted number

7. Or character (extended regular expression character)

Grep-e "Ou|se" matches rows with OUs or SE

8.egrep and Fgrep

Egrep "Ou|se" file

Egrep "^-+b" file match begins with a "-" or "-" and a line containing B is followed

Fgrep CA file only matches characters

[0-9]*. [A-za-z] [A-z-a-z]

*.doc *.txt *.ppt *.docx *.pptx

Grep-n-I chapter *.doc.

Grep-n [CC][HH][AA][PP][TT][EE][RR] *.doc ...

Grep-r-C ^$ *

Grep-c ^$ *

GREP-E: $| [^[:alpha]]

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The grep command usage for Shell Scripting Learning notes