Paging Through Files (less)

The less command lets you page through files one screen at a time. It's perfect for reading large files.

Basic Usage

less filename

Why "less"?

The name comes from the phrase "less is more" - less is an improved version of an older command called more.

Navigation in less

Key	Action
Space / f	Forward one page
b	Back one page
d	Forward half page
u	Back half page
g	Go to beginning
G	Go to end
q	Quit

Searching in less

Key	Action
/pattern	Search forward
?pattern	Search backward
n	Next match
N	Previous match

Example:

1. Open file with less file.txt
2. Type /error to search for "error"
3. Press n to find next occurrence

less Options

Option	Description
-N	Show line numbers
-S	Chop long lines (no wrap)
-i	Case-insensitive search
-F	Quit if file fits on screen
+G	Start at end of file

Exercise: Page Through a File

Use less to view a log file:

less vs cat vs more

Feature	cat	more	less
Scroll back	No	No	Yes
Search	No	Limited	Yes
Large files	Bad	OK	Best
Navigation	None	Forward	Both

Useful less Commands

Line Numbers

less -N file.txt

Follow File (like tail -f)

less +F /var/log/syslog

Start at Pattern

less +/error logfile.txt

Multiple Files

less file1.txt file2.txt
# :n - next file
# :p - previous file

Viewing Piped Output

cat /var/log/*.log | less
history | less
ps aux | less

Common Patterns

View Logs

less /var/log/syslog
less -N +G /var/log/auth.log    # With line numbers, at end

Read Documentation

man ls | less                    # Actually uses less

Key Takeaways

• less is ideal for viewing large files
• Navigate with Space, b, g, G
• Search with /pattern
• Press q to quit
• Better than cat for anything over one screen