$ less <filename>

Navigation

SPACE or CTRL+F forward one window
b or CTRL+B backward one window
d or CTRL+D forward half window
u CTRL+U backward half window
j navigate forward by one line
10j 10 lines forward.
k navigate backward by one line
10k 10 lines backward.
G go to the end of the file
g go to the start of the file
q or ZZ exit the less pager

Forward search

/ search forward for a pattern
n move forward for the next occurrence.
N move backward for the previous occurrence

Backward search

? search backward for a pattern
n move backward for the next occurrence.
N move forward for the previous occurrence

Other commands

F Follow the end of the file as more lines are added, similar to tail -f.
m<any-lower-letter> Mark the current position with the letter the specified lower letter,
‘<lower-letter> go to the marked position marked with the specified lower letter.
&pattern display only the matching lines, not all.
v Open the current file in the default editor.
CTRL+G or = show the current file name along with line, byte, and percentage statistics.
h display help
:e filename While viewing a file with less this command allows you to open/examine a.
:n go to the next file
:p go to the previous file

Options