<s>
pax	B-Device
is	O
an	O
archiving	B-Application
utility	I-Application
available	O
for	O
various	O
operating	B-General_Concept
systems	I-General_Concept
and	O
defined	O
since	O
1995	O
.	O
</s>
<s>
Rather	O
than	O
sort	O
out	O
the	O
incompatible	O
options	O
that	O
have	O
crept	O
up	O
between	O
tar	B-Application
and	O
cpio	B-Application
,	O
along	O
with	O
their	O
implementations	O
across	O
various	O
versions	O
of	O
Unix	B-Application
,	O
the	O
IEEE	O
designed	O
new	O
archive	O
utility	O
pax	B-Device
that	O
could	O
support	O
various	O
archive	O
formats	O
with	O
useful	O
options	O
from	O
both	O
archivers	O
.	O
</s>
<s>
The	O
pax	B-Device
command	B-Application
is	O
available	O
on	O
Unix	B-Application
and	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
and	O
on	O
IBM	B-Application
i	I-Application
,	O
and	O
Microsoft	B-Device
Windows	I-Device
NT	I-Device
until	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
In	O
2001	O
,	O
IEEE	O
defined	O
a	O
new	O
pax	B-Device
format	O
which	O
is	O
basically	O
tar	B-Application
with	O
additional	O
extended	O
attributes	O
.	O
</s>
<s>
The	O
format	O
is	O
not	O
supported	O
by	O
pax	B-Device
commands	O
in	O
most	O
Linux	B-Application
distributions	I-Application
and	O
in	O
FreeBSD	B-Operating_System
,	O
but	O
it	O
is	O
supported	O
by	O
tar	B-Application
commands	I-Application
from	O
GNU	O
and	O
FreeBSD	B-Operating_System
;	O
the	O
format	O
is	O
further	O
supported	O
by	O
pax	B-Device
commands	O
in	O
AIX	O
,	O
Solaris	O
and	O
HP-UX	B-Application
.	O
</s>
<s>
The	O
name	O
"	O
pax	B-Device
"	O
is	O
an	O
acronym	O
for	O
portable	B-Device
archive	I-Device
exchange	I-Device
.	O
</s>
<s>
The	O
command	B-Application
invocation	O
and	O
structure	O
is	O
somewhat	O
a	O
unification	O
of	O
both	O
tar	B-Application
and	O
cpio	B-Application
.	O
</s>
<s>
The	O
first	O
public	O
implementation	O
of	O
pax	B-Device
was	O
written	O
by	O
Mark	O
H	O
.	O
Colburn	O
in	O
1989	O
.	O
</s>
<s>
Colburn	O
posted	O
it	O
to	O
as	O
Usenix/IEEE	O
POSIX	O
replacement	O
for	O
TAR	B-Application
and	O
CPIO	B-Application
.	O
</s>
<s>
Manual	O
pages	O
for	O
pax	B-Device
on	O
HP-UX	B-Application
,	O
IRIX	B-Operating_System
,	O
and	O
SCO	B-Operating_System
UNIX	I-Operating_System
attribute	O
pax	B-Device
to	O
Colburn	O
.	O
</s>
<s>
As	O
early	O
as	O
POSIX.2	O
draft	O
10	O
from	O
July	O
1990	O
covers	O
pax	B-Device
command	B-Application
.	O
</s>
<s>
Furthermore	O
,	O
POSIX.2	O
and	O
IEEE	O
1003.1b	O
drafts	O
in	O
1991	O
cover	O
pax	B-Device
command	B-Application
,	O
featuring	O
cpio	B-Application
and	O
ustar	O
archive	O
formats	O
.	O
</s>
<s>
Another	O
version	O
of	O
the	O
pax	B-Device
program	O
was	O
created	O
by	O
Keith	O
Muller	O
in	O
1992	O
–	O
1993	O
.	O
</s>
<s>
Pax	B-Device
command	B-Application
appeared	O
in	O
X/Open	O
issue	O
4	O
(	O
Single	O
Unix	B-Application
Specification	O
version	O
1	O
)	O
in	O
1995	O
,	O
featuring	O
cpio	B-Application
and	O
ustar	O
archive	O
formats	O
,	O
which	O
were	O
also	O
the	O
only	O
two	O
formats	O
featuring	O
in	O
the	O
1997	O
Single	O
Unix	B-Application
Specification	O
.	O
</s>
<s>
This	O
method	O
was	O
accepted	O
for	O
the	O
POSIX.1-2001	O
standard	O
as	O
the	O
new	O
pax	B-Device
file	O
format	O
.	O
</s>
<s>
pax	B-Device
has	O
four	O
general	O
modes	O
that	O
are	O
invoked	O
by	O
a	O
combination	O
of	O
the	O
(	O
"	O
read	O
"	O
)	O
and	O
(	O
"	O
write	O
"	O
)	O
options	O
.	O
</s>
<s>
This	O
model	O
is	O
similar	O
to	O
cpio	B-Application
,	O
which	O
has	O
a	O
similar	O
set	O
of	O
basic	O
operations	O
.	O
</s>
<s>
By	O
default	O
,	O
pax	B-Device
uses	O
the	O
standard	O
input/output	O
for	O
archive	O
and	O
listing	O
operations	O
.	O
</s>
<s>
This	O
can	O
be	O
changed	O
with	O
the	O
"	O
tar-style	O
"	O
option	O
that	O
specifies	O
the	O
archive	O
file	O
.	O
</s>
<s>
Pax	B-Device
differs	O
from	O
cpio	B-Application
by	O
recursively	O
considering	O
the	O
content	O
of	O
a	O
directory	O
;	O
to	O
disable	O
this	O
behavior	O
,	O
POSIX	O
pax	B-Device
has	O
an	O
option	O
to	O
disable	O
it	O
.	O
</s>
<s>
The	O
command	B-Application
is	O
a	O
mish-mash	O
of	O
and	O
features	O
.	O
</s>
<s>
Like	O
,	O
processes	O
directory	O
entries	O
recursively	O
,	O
a	O
feature	O
that	O
can	O
be	O
disabled	O
with	O
for	O
cpio-style	O
behavior	O
.	O
</s>
<s>
The	O
handling	O
of	O
file	O
input/outputs	O
is	O
also	O
a	O
mix	O
:	O
when	O
a	O
list	O
of	O
file	O
names	O
is	O
specified	O
on	O
the	O
command	B-Application
line	O
,	O
they	O
are	O
taken	O
as	O
shell	B-Language
globs	I-Language
for	O
file	O
input	O
or	O
listing	O
(	O
tar-like	O
)	O
;	O
otherwise	O
takes	O
the	O
-style	O
behavior	O
of	O
using	O
the	O
standard	O
input	O
for	O
a	O
file	O
list	O
.	O
</s>
<s>
Finally	O
,	O
supports	O
reading/writing	O
to	O
a	O
named	O
archive	O
file	O
using	O
tar	B-Application
's	O
option	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
one	O
desires	O
a	O
cpio-style	O
archiving	O
of	O
the	O
current	O
directory	O
,	O
can	O
be	O
used	O
with	O
just	O
like	O
one	O
does	O
using	O
cpio	B-Application
:	O
</s>
<s>
The	O
command	B-Application
for	O
extracting	O
the	O
contents	O
for	O
an	O
archive	O
is	O
the	O
same	O
as	O
:	O
</s>
<s>
It	O
is	O
possible	O
to	O
invoke	O
these	O
commands	O
in	O
a	O
tar-like	O
syntax	O
as	O
well	O
:	O
</s>
<s>
Most	O
implementations	O
of	O
pax	B-Device
use	O
the	O
(	O
gzip	B-Application
)	O
and	O
(	O
bzip2	B-Application
)	O
switches	O
for	O
compression	O
;	O
this	O
feature	O
however	O
,	O
is	O
not	O
specified	O
by	O
POSIX	O
.	O
</s>
<s>
It	O
is	O
important	O
to	O
note	O
that	O
pax	B-Device
cannot	O
append	O
to	O
compressed	O
archives	O
.	O
</s>
<s>
As	O
in	O
tar	B-Application
and	O
cpio	B-Application
,	O
pax	B-Device
output	O
can	O
be	O
piped	O
to	O
another	O
compressor/decompressor	O
program	O
.	O
</s>
<s>
As	O
an	O
example	O
xz	B-Language
is	O
used	O
here	O
:	O
</s>
<s>
and	O
listing	O
an	O
xz-compressed	O
archive	O
as	O
the	O
input	O
:	O
</s>
<s>
POSIX.1-2001	O
requires	O
that	O
pax	B-Device
command	B-Application
supports	O
the	O
archive	O
formats	O
cpio	B-Application
,	O
ustar	O
and	O
pax	B-Device
at	O
a	O
minimum	O
.	O
</s>
<s>
The	O
versions	O
of	O
pax	B-Device
command	B-Application
that	O
stem	O
from	O
the	O
4.4BSD	O
implementation	O
usually	O
inherit	O
the	O
formats	O
supported	O
by	O
that	O
version	O
,	O
selectable	O
via	O
the	O
option	O
:	O
</s>
<s>
cpio	B-Application
–	O
The	O
extended	O
cpio	B-Application
interchange	O
format	O
specified	O
in	O
the	O
IEEE	O
Std	O
1003.2	O
(	O
"	O
POSIX.2	O
"	O
)	O
standard	O
.	O
</s>
<s>
bcpio	O
–	O
The	O
old	O
binary	O
cpio	B-Application
format	O
.	O
</s>
<s>
sv4cpio	O
–	O
The	O
System	O
V	O
release	O
4	O
cpio	B-Application
.	O
</s>
<s>
sv4crc	O
–	O
The	O
System	O
V	O
release	O
4	O
cpio	B-Application
with	O
file	O
crc	O
checksums	O
.	O
</s>
<s>
tar	B-Application
–	O
The	O
old	O
BSD	O
tar	B-Application
format	O
as	O
found	O
in	O
BSD4.3	O
.	O
</s>
<s>
ustar	O
(	O
default	O
)	O
–	O
The	O
tar	B-Application
interchange	O
format	O
specified	O
in	O
the	O
IEEE	O
Std	O
1003.2	O
(	O
"	O
POSIX.2	O
"	O
)	O
standard	O
.	O
</s>
<s>
The	O
POSIX.1-2001	O
pax	B-Device
format	O
is	O
not	O
supported	O
by	O
this	O
BSD	O
version	O
of	O
pax	B-Device
command	B-Application
.	O
</s>
<s>
The	O
format	O
is	O
not	O
supported	O
on	O
most	O
Linux	B-Application
distributions	I-Application
(	O
whose	O
pax	B-Device
command	B-Application
is	O
from	O
the	O
MirBSD	B-Application
branch	O
of	O
MirCPIO-paxmirabilis	O
)	O
and	O
on	O
FreeBSD	B-Operating_System
.	O
</s>
<s>
The	O
format	O
is	O
supported	O
by	O
pax	B-Device
command	B-Application
in	O
AIX	O
,	O
Solaris	O
and	O
HP-UX	B-Application
.	O
</s>
<s>
It	O
is	O
further	O
supported	O
by	O
Python	O
tarfile	B-Application
module	O
,	O
by	O
BSD-licensed	O
libarchive	O
,	O
by	O
7-ZIP	O
and	O
further	O
by	O
GNU	B-Application
tar	I-Application
and	O
FreeBSD	B-Operating_System
tar	B-Application
.	O
</s>
<s>
The	O
Heirloom	B-Device
Project	I-Device
pax	B-Device
command	B-Application
,	O
developed	O
by	O
Gunnar	O
Ritter	O
in	O
2003	O
,	O
supports	O
the	O
pax	B-Device
format	O
as	O
well	O
as	O
many	O
extra	O
formats	O
.	O
</s>
<s>
pax	B-Device
supports	O
archiving	O
on	O
multiple	O
volumes	O
.	O
</s>
<s>
When	O
restoring	O
an	O
archive	O
from	O
multiple	O
media	O
,	O
pax	B-Device
asks	O
for	O
the	O
next	O
media	O
in	O
the	O
same	O
fashion	O
,	O
when	O
the	O
end	O
of	O
the	O
media	O
is	O
reached	O
before	O
the	O
end	O
of	O
the	O
archive	O
.	O
</s>
<s>
Despite	O
being	O
standardized	O
in	O
2001	O
by	O
IEEE	O
,	O
as	O
of	O
2010	O
,	O
pax	B-Device
enjoys	O
relatively	O
little	O
popularity	O
or	O
adoption	O
.	O
</s>
<s>
This	O
is	O
in	O
part	O
because	O
there	O
was	O
not	O
any	O
need	O
for	O
it	O
from	O
the	O
Unix	B-Application
users	O
;	O
it	O
was	O
just	O
the	O
POSIX	O
committee	O
that	O
wants	O
to	O
have	O
a	O
more	O
consistent	O
interface	O
.	O
</s>
<s>
Pax	B-Device
is	O
also	O
fairly	O
chatty	O
and	O
expects	O
user	O
interactions	O
when	O
things	O
go	O
wrong	O
.	O
</s>
<s>
pax	B-Device
is	O
required	O
to	O
be	O
present	O
in	O
all	O
conformant	O
systems	O
by	O
Linux	B-Application
Standard	I-Application
Base	I-Application
since	O
version	O
3.0	O
(	O
released	O
on	O
July	O
6	O
,	O
2005	O
)	O
,	O
but	O
so	O
far	O
few	O
Linux	B-Application
distributions	I-Application
ship	O
and	O
install	O
it	O
by	O
default	O
.	O
</s>
<s>
However	O
,	O
most	O
distributions	O
include	O
pax	B-Device
as	O
a	O
separately	O
installable	O
package	O
.	O
</s>
<s>
pax	B-Device
has	O
also	O
been	O
present	O
in	O
Windows	B-Device
NT	I-Device
,	O
where	O
it	O
is	O
limited	O
to	O
file	O
archives	O
(	O
tapes	O
not	O
supported	O
)	O
.	O
</s>
<s>
It	O
was	O
later	O
moved	O
to	O
the	O
Interix	B-Operating_System
subsystem	O
.	O
</s>
<s>
It	O
does	O
not	O
support	O
archiving	O
or	O
restoring	O
Win32	B-Library
ACLs	O
.	O
</s>
<s>
pax	B-Device
was	O
further	O
present	O
in	O
Windows	B-Application
2000	I-Application
.	O
</s>
<s>
Packages	O
handled	O
by	O
the	O
Installer	O
(	O
macOS	O
)	O
often	O
carry	O
the	O
bulk	O
of	O
their	O
contents	O
in	O
an	O
Archive.pax.gz	O
file	O
that	O
may	O
be	O
read	O
using	O
the	O
system	O
's	O
pax	B-Device
(	O
heirloom	O
)	O
utility	O
.	O
</s>
