To view files instead of opening the file to
view in an editor, Less is similar to more command, but less allows both
forward and backward movements. Moreover, less don’t require to load the whole
file before viewing. Try opening a large log file in Vim editor and less —
you’ll see the speed difference.
The navigation keys in less command are similar
to Vim editor. In this article, let us look at few less command navigation and
other operations which will make you a better command line warrior.
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 file2
Method 2: While you are viewing file1, use :e
to open the file2 as shown below.
# less file1
:e file2
Navigation 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.
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