less

1. Less Command – Search Navigation

Once you’ve opened a log file (or any file) using less file-name, use the following keys to search. Please note that the match will be highlighted automatically by default.

Forward Search

• / – search for a pattern which will take you to the next occurrence.
• n – for next match in forward
• N – for previous match in backward

Backward Search

• ? – search for a pattern which will take you to the previous occurrence.
• n – for next match in backward direction
• N – for previous match in forward direction
Tip: If you dont bother about which direction the search is happening, and you want to search file path, or URL, such as “/home/ramesh/”, you can use backward search (?pattern) which will be handy as you don’t want to escape slashes each time.
Search Path
In forward: /\/home\/ramesh\/
In backward: ?/home/ramesh/

2. Less Command – Screen Navigation

Use the following screen navigation commands while viewing large log files.
• CTRL+F – forward one window
• CTRL+B – backward one window
• CTRL+D – forward half window
• CTRL+U – backward half window

3. Less Command – Line navigation

In a smaller chunk of data, where you want to locate particular error, you may want to navigate line by line using these keys:
• j – navigate forward by one line
• k – navigate backward by one line

4. Less Command – Other Navigations

The following are other navigation operations that you can use inside the less pager.
• G – go to the end of file
• g – go to the start of file
• q or ZZ – exit the less pager

5. Simulate tail -f inside less pager – Press F

Once you’ve opened a file using less command, any content that is appended to the file after that will not be displayed automatically. However, you can press F less command will show the status ‘waiting for data‘. This is as similar to ‘tail -f’.
Also, refer to our earlier article about how to view multiple logs files using tail -f.

6. Less Command – Count magic

Similar to Vim editor navigation command, you can give 10j to scroll 10 lines down, or 10k to go up by 10 lines.
• 10j – 10 lines forward.
• 10k – 10 lines backward.
• CTRL+G – show the current file name along with line, byte and percentage statistics.

7. Other useful Less Command Operations

• v – using the configured editor edit the current file.
• h – summary of less commands
• &pattern – display only the matching lines, not all.

8. Open any types of files using less command

As we discussed in our earlier article, you can use less command to Open & view 10 different file types.

9. Less Command – Marked navigation

When you are viewing a large log file using less command, you can mark a particular position and return back to that place again by using that mark.
• ma – mark the current position with the letter ‘a’,
• ‘a – go to the marked position ‘a’.

10. Less Command – Multiple file paging

Method 1: You can open multiple files by passing the file names as arguments.
$ less file1 file2Method 2: While you are viewing file1, use :e to open the file2 as shown below.
$ less file1
:e file2Navigation across files: When you opened more than two files ( for e.g – less * ), use the following keys to navigate between files.
• :n – go to the next file.
• :p – go to the previous file.