How to find files in Linux

How to find files in Linux: 1. Use the find command to search according to the attributes of the file, such as file name, file size, owner, group to which it belongs, whether it is empty, access time, modification time, etc. 2. Use the locate command to check the file location with the database. Use the whereis command to find specific files. It can only be used to find binary files, source code files, and man pages. 4. Use the which command to view the location of the executable file. 5. Use the type command to search. 6. Use grep command to search.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

find command to find files

Using the Linux find command, you can use different search criteria such as name, type, owner, size Wait to search the directory tree. The basic syntax is as follows:

# find path expression search-term

The following is an example of using the find command to find a specific file based on the file name:

# find -name test.file

The command will search the entire directory tree to find a file named test.file, And its storage location will be provided. You can try it using an existing filename on your Linux.
The find command can sometimes take several minutes to find the entire directory tree, especially if there are many files and directories in the system. To significantly reduce time, you can specify the directories to search. For example, if you know that test.file exists in /var, there is no need to search other directories. In this way, you can use the following command:

# find /var -name test.file

find You can also search for files based on options such as time, size, owner, permissions, and more. To learn more about these options, you can view the manual of the Linux find command.

# man find

locate command finds files

To use the locate command in Linux, you first need to install it.

If you are using Ubuntu, run the following command to install locate:

# apt-get update# apt-get install mlocate

If you are using CentOS, run the following command to install locate:

# yum install mlocate

locate is a faster way than find because it looks for the file in the database. To update the search database, run the following command:

# updatedb

Syntax for finding files using locate:

# locate test.file

Just like the find command, locate also has many options for filtering the output. To learn more you can check the manual of Linux Locate command.

# man locate

whereis command searches for files

whereis command can only be used to search for program names, and only binary files (parameter -b) , man description file (parameter -m) and source code file (parameter -s). If parameters are omitted, all information is returned.

Usage examples of whereis command:

　　$ whereis grep

Description: whereis looks for specific files and can only be used to find binary files, source code files and man manual pages

which command searches for files

which checks the location of the executable file. Only programs with environment variables set can use the

which command. Yes, in the path specified by the PATH variable, search for the location of a certain system command and return the first search result. In other words, using the which command, you can see whether a certain system command exists and where the command is executed.

Usage examples of which command:

　　$ which grep

type command to find files

type command is not actually a search command, it It is used to distinguish whether a command comes with the shell or is provided by an independent binary file outside the shell. If a command is an external command, then using the -p parameter will display the path of the command, which is equivalent to the which command.

Usage examples of type command:

　　$ type cd

The system will prompt that cd is the shell’s built-in command (build-in).

　　$ type grep

The system will prompt that grep is an external command and display the path of the command.

　　$ type -p grep

After adding the -p parameter, it is equivalent to the which command.

The grep command searches for files

grep searches based on the contents of the file, and will match each line of the file according to the given pattern (patter ) to perform a matching search.

Basic format:

find [options] expression

Main parameters:

[options]Main parameters:

• -c: Output only matching lines count.

• -i: Case-insensitive

• -h: File names are not displayed when querying multiple files.

• -l: When querying multiple files, only the file names containing matching characters are output.

• -n: Display matching lines and line numbers.

• -s: Do not display error messages that do not exist or have no matching text.

• -v: Display all lines that do not contain matching text.

pattern Main parameters of regular expression:

• \: Ignore the original meaning of special characters in the regular expression.

• ^: Matches the starting line of the regular expression.

• $: Matches the end line of the regular expression.

• \<: Start from the line matching the regular expression.

• \>: To the end of the line matching the regular expression.

• [ ]: A single character, such as [A], that is, A meets the requirements.

• [ - ]: Range, such as [A-Z], that is, A, B, C to Z all meet the requirements.

• .: All single characters.

• *: There are characters, and the length can be 0.

Example:

grep -r "string" is very convenient

1)grep 'test' d*　# Display the lines containing test in all files starting with d

2)grep 'test' aa bb cc　 #Display the lines containing test in the aa, bb, cc files

3)grep '[a-z]\{5\}' aa　#Display all lines containing strings with at least 5 consecutive lowercase characters per line of string

4 )grep magic /usr/src　#Display the files in the /usr/src directory (excluding subdirectories) containing magic lines

5)grep -r magic /usr /src　#Display files in the /usr/src directory (including subdirectories) containing magic lines

6)grep -w pattern files: Only match the entire word, and Not part of the string (such as matching 'magic', not 'magical'),

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