<s>
The	O
command	B-Application
in	O
Unix	B-Application
,	O
Plan	B-Application
9	I-Application
,	O
Inferno	B-Operating_System
,	O
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
is	O
used	O
to	O
format	O
natural	O
language	O
text	O
for	O
humans	O
to	O
read	O
.	O
</s>
<s>
The	O
command	B-Application
has	O
been	O
traditionally	O
used	O
to	O
reformat	O
email	O
messages	O
after	O
composition	O
and	O
prior	O
to	O
delivery	O
.	O
</s>
<s>
Its	O
syntax	O
is	O
similar	O
among	O
various	O
Unixes	B-Application
,	O
but	O
not	O
identical	O
.	O
</s>
<s>
attempts	O
to	O
break	O
,	O
fill	O
and	O
join	O
input	O
lines	O
to	O
produce	O
globally	O
optimal	O
,	O
balanced	O
output	O
with	O
the	O
lengths	O
of	O
each	O
line	O
approaching	O
the	O
target	O
width	O
as	O
closely	O
as	O
possible	O
,	O
rather	O
than	O
wrapping	O
the	O
input	O
lines	O
exactly	O
as	O
(	O
from	O
GNU	B-Application
Core	I-Application
Utilities	I-Application
)	O
does	O
.	O
</s>
<s>
In	O
most	O
implementations	O
of	O
,	O
the	O
word	B-Algorithm
wrap	I-Algorithm
optimization	O
procedure	O
usually	O
requires	O
two	O
criteria	O
:	O
the	O
target	O
output	O
line	O
width	O
,	O
and	O
the	O
maximum	O
acceptable	O
line	O
width	O
(	O
which	O
should	O
be	O
larger	O
than	O
the	O
previous	O
one	O
to	O
give	O
room	O
for	O
optimization	O
)	O
.	O
</s>
<s>
For	O
example	O
,	O
early	O
versions	O
of	O
GNU	B-Operating_System
can	O
only	O
accept	O
the	O
maximum	O
width	O
option	O
,	O
which	O
is	O
given	O
by	O
switch	O
,	O
or	O
directly	O
as	O
the	O
first	O
command	B-Application
line	O
option	O
for	O
compatibility	O
(	O
later	O
versions	O
use	O
to	O
specify	O
the	O
goal	O
width	O
and	O
for	O
the	O
maximum	O
width	O
)	O
.	O
</s>
<s>
See	O
the	O
Solaris	B-Application
man	B-Protocol
page	I-Protocol
for	O
and	O
FreeBSD	B-Operating_System
manual	O
entry	O
for	O
for	O
detailed	O
examples	O
,	O
and	O
compare	O
with	O
the	O
latest	O
documentation	O
of	O
GNU	B-Operating_System
utility	O
included	O
by	O
most	O
Linux	B-Application
distributions	I-Application
.	O
</s>
<s>
See	O
also	O
the	O
Plan	B-Application
9	I-Application
man	B-Protocol
page	I-Protocol
.	O
</s>
<s>
The	O
command	B-Application
is	O
available	O
as	O
a	O
separate	O
package	O
for	O
Microsoft	B-Application
Windows	I-Application
as	O
part	O
of	O
the	O
UnxUtils	B-Application
collection	O
of	O
native	B-Language
Win32	B-Library
ports	O
of	O
common	O
GNU	B-Operating_System
Unix-like	B-Operating_System
utilities	O
.	O
</s>
