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Preface

In the Linux system to search and find the contents of the file, generally the most commonly used is the grep command, in addition, there is an egrep command, while the vi command also supports file content retrieval. Let's take a look at the details of how Linux uses the grep command to retrieve the contents of a file.

The methods are as follows:

1. Search for whether a file contains a string

Command format: grep "found string" filename1

For example:

Grep "0101034175" / data/transaction.20170118.log

2. Retrieve a string in multiple files

Command format:

Grep "found string t" filename1 filename2 filename3... grep "found string" * .log

3. Display the number of lines of the retrieved content in the file. You can use the parameter-n

Command format: grep-n "found string" * .log

4. The case problem needs to be ignored when searching, and the parameter "- I" can be used.

Command format: grep-I "found string" * .log

5. Find lines that do not match the specified string from the contents of the file

Command format: grep-v "found string" file name

6. Search and find the number of matching rows:

Command format:

Grep-c "found string" file name "grep" found string "file name | wc-l

7. Recursively search for all files in a directory and subdirectories

Command format: grep-r "found string" file directory

8. Get which files contain the contents of the search, and list the file names

Command format: grep-H-r "found string" file directory | cut-d:-F1 [| uniq]

For example:

Grep-H-r "v\ $temp_space_header" / u01/app/Oracle/product/11.1.0/dbhome_1/rdbms/admin/ | cut-d:-f1grep-H-r "v\ $temp_space_header" / u01/app/oracle/product/11.1.0/dbhome_1/rdbms/admin/ | cut-d:-F1 | uniq

9. Get the content that matches the entire search character

Command format: grep-w "found string" filename

10. The combination of grep command and find command to realize joint retrieval.

Command format: find. -name'* .sql'- exec grep-I 'retrieved content' {}\;-print

For example:

Find. -name'* .SQL'- exec grep-I'v\ $temp_space_header' {}\;-print

The difference between Linux grep and find

These are two different commands about grep:

Grep command is a powerful text search tool in Linux system. It can use regular expressions to search text and print matching lines. The full name of grep is Global Regular Expression Print, which represents the global regular expression version, and its permission is for all users.

And find under linux (for more information, please see here: https://www.jb51.net/article/108198.htm)

Function: search for files in the directory structure and perform specified operations. This command provides quite a number of search criteria and is very powerful.

Syntax: find start directory search condition operation

Description: the find command starts from the specified starting directory, recursively searches its subdirectories, finds files that meet the search criteria and takes relevant actions on them.

So to put it simply, grep is a line to find matching criteria, and find is a file to search for matching criteria.

Summary

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