Overview
As its name 'less is more' suggests, `less` was created to overcome the shortcomings of the `more` command. While `more` can only scroll file content forward, `less` allows free movement up and down pages. It also offers powerful search functions similar to the `vi` editor and real-time file content updates (via the `F` key). `less` does not load the entire file into memory but reads only the necessary parts, allowing quick viewing of large files, even those several gigabytes (GB) in size.
Key Features
The main features of the `less` command are as follows:
- Can freely scroll file content forwards and backwards.
- Efficiently uses memory even when viewing large files.
- Provides powerful search and navigation functions similar to `vi`.
- Can monitor files with continuously added content, such as log files, in real-time.
- Included by default in most Linux distributions.
Difference between less and more
`less` includes all the features of `more` and provides even more advanced functionalities.
- less: Allows free scrolling of files forwards and backwards. Provides various editor-like functionalities in addition to scrolling.
- more: Can only scroll files forward. Once content has passed, it cannot be viewed again.
Main Options
The `less` command controls output methods through various options. However, most are controlled via keyboard shortcuts in interactive mode.
1) Execution Options
2) Interactive Mode Keyboard Shortcuts
Generated command:
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Description:
`less` Executes the command.
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Usage Examples
Learn the features of the `less` command through various usage examples.
Explore file content
less /var/log/syslogFreely explores the content of a large file, `/var/log/syslog`.
Use with pipe (|)
dmesg | lessPipes the output of the `dmesg` command to `less` to view it page by page, navigating forwards and backwards.
Start from end of file
less +G /var/log/nginx/access.logThe `+G` option is useful for starting at the end of a file to immediately see the latest logs.
Output with line numbers
less -N /etc/fstabUses the `-N` option to output each line prefixed with its number.
Tips & Cautions
Here are some points to note when using the `less` command.
Tips
- `less` uses many shortcuts similar to `vi`. For example, `g` moves to the very beginning of the file, and `G` moves to the very end.
- When viewing files where content is continuously added, such as log files, open it with `less` and then press the `F` key to switch to real-time monitoring mode, similar to `tail -f`. To exit this mode, press `Ctrl+C`.