How to search for specific content within a Linux file?

To search for specific content in a Linux file, you can use the following command:

1. The grep command is used to search for specified content in a file and print out the lines that contain that content. For example, grep “specified content” filename.
2. The find command is used to search for files in a specified directory and its subdirectories, and then perform a specified operation on them. For example, you can use the find command with options like -name to specify the file name and -exec to execute grep with a specified content on the files found.
3. Ack command: Ack command is a replacement for grep, which is more convenient and faster when searching for content. For example: ack “specified content” filename.
4. ag command: The ag command is an improved version of ack and is also a fast search tool.
   For example: ag “specified content” file name
5. SED command: The SED command is used to manipulate text streams by searching and replacing specific content.
   For example: SED ‘/specified content/!d’ filename

The above are several common methods, the specific method you choose depends on your needs and preferences.