<s>
less	O
is	O
a	O
terminal	B-General_Concept
pager	I-General_Concept
program	B-Application
on	O
Unix	B-Application
,	O
Windows	B-Application
,	O
and	O
Unix-like	B-Operating_System
systems	I-Operating_System
used	O
to	O
view	O
(	O
but	O
not	O
change	O
)	O
the	O
contents	O
of	O
a	O
text	B-General_Concept
file	I-General_Concept
one	O
screen	O
at	O
a	O
time	O
.	O
</s>
<s>
Unlike	O
most	O
Unix	B-Application
text	O
editors/viewers	O
,	O
does	O
not	O
need	O
to	O
read	O
the	O
entire	O
file	O
before	O
starting	O
,	O
allowing	O
for	O
immediate	O
viewing	O
regardless	O
of	O
file	O
size	O
.	O
</s>
<s>
Mark	O
Nudelman	O
initially	O
wrote	O
less	O
during	O
1983	O
–	O
85	O
,	O
in	O
the	O
need	O
of	O
a	O
version	O
of	O
more	B-Device
able	O
to	O
do	O
backward	O
scrolling	O
of	O
the	O
displayed	O
text	O
.	O
</s>
<s>
The	O
name	O
came	O
from	O
the	O
joke	O
of	O
doing	O
"	O
backwards	O
more.	O
"	O
</s>
<s>
Originally	O
,	O
less	O
was	O
developed	O
for	O
Unix	B-Application
,	O
but	O
it	O
has	O
been	O
ported	O
to	O
a	O
number	O
of	O
other	O
operating	O
systems	O
,	O
including	O
MS-DOS	B-Application
,	O
Microsoft	B-Application
Windows	I-Application
,	O
OS/2	B-Application
,	O
and	O
OS-9	B-Operating_System
,	O
as	O
well	O
as	O
Unix-like	B-Operating_System
systems	I-Operating_System
such	O
as	O
Linux	B-Application
.	O
</s>
<s>
To	O
help	O
remember	O
the	O
difference	O
between	O
less	O
and	O
more	B-Device
,	O
a	O
common	O
joke	O
is	O
to	O
say	O
,	O
"	O
,	O
"	O
implying	O
that	O
less	O
has	O
greater	O
functionality	O
than	O
.	O
</s>
<s>
A	O
similar	O
saying	O
is	O
that	O
"	O
less	O
is	O
more	B-Device
,	O
more	B-Device
or	O
less	O
"	O
.	O
</s>
<s>
If	O
the	O
file	O
name	O
argument	O
is	O
omitted	O
,	O
it	O
displays	O
the	O
contents	O
from	O
standard	O
input	O
(	O
usually	O
the	O
output	O
of	O
another	O
command	O
through	O
a	O
pipe	B-Operating_System
)	O
.	O
</s>
<s>
If	O
the	O
output	O
is	O
redirected	O
to	O
anything	O
other	O
than	O
a	O
terminal	B-General_Concept
,	O
for	O
example	O
a	O
pipe	B-Operating_System
to	O
another	O
command	O
,	O
behaves	O
like	O
.	O
</s>
<s>
The	O
"	O
lesspipe	O
"	O
extension	O
can	O
automatically	O
determine	O
file	O
types	O
such	O
as	O
PDF	B-Application
,	O
multimedia	O
,	O
and	O
compressed	B-Application
archives	I-Application
,	O
and	O
automatically	O
determines	O
which	O
program	B-Application
to	O
launch	O
display	O
the	O
file	O
's	O
information	O
with	O
,	O
such	O
as	O
text	O
from	O
a	O
PDF	B-Application
file	I-Application
,	O
metadata	O
of	O
photos	O
,	O
lists	O
of	O
files	O
in	O
a	O
compressed	B-Application
archive	I-Application
,	O
and	O
content	O
of	O
a	O
single	O
file	O
in	O
a	O
compressed	B-Application
archive	I-Application
.	O
</s>
<s>
The	O
command-syntax	O
is	O
:	O
</s>
<s>
-m	O
:	O
Show	O
more	B-Device
detailed	O
prompt	O
,	O
including	O
file	O
position	O
.	O
</s>
<s>
Text	O
is	O
interpreted	O
as	O
a	O
regex	B-Language
.	O
</s>
<s>
Backward	O
Search	O
like	O
grep	B-Application
like	O
filter	O
Next	O
Search	O
Match	O
Previous	O
Search	O
Match	O
Turn	O
off	O
Match	O
Highlighting	O
(	O
see	O
-g	O
command	O
line	O
option	O
)	O
Toggle	O
option	O
,	O
e.g.	O
,	O
toggles	O
option	O
to	O
match	O
case	O
in	O
searches	O
Set	O
Mark	O
Go	O
to	O
Mark	O
or	O
File	O
information	O
Next	O
file	O
Previous	O
file	O
Help	O
.	O
</s>
<s>
This	O
is	O
most	O
relevant	O
when	O
less	O
is	O
directly	O
accessing	O
a	O
named	O
file	O
that	O
is	O
modified	O
or	O
deleted	O
while	O
less	O
is	O
still	O
running	O
,	O
and	O
when	O
less	O
is	O
receiving	O
data	O
from	O
a	O
pipe	B-Operating_System
and	O
the	O
data	O
can	O
not	O
be	O
randomly	O
accessed	O
or	O
regenerated	O
.	O
</s>
