<s>
In	O
the	O
Unix	B-Application
operating	I-Application
system	I-Application
,	O
shar	B-General_Concept
(	O
an	O
abbreviation	O
of	O
shell	B-General_Concept
archive	I-General_Concept
)	O
is	O
an	O
archive	B-General_Concept
format	I-General_Concept
created	O
with	O
the	O
Unix	B-Application
shar	B-General_Concept
utility	O
.	O
</s>
<s>
A	O
shar	B-General_Concept
file	O
is	O
a	O
type	O
of	O
self-extracting	B-General_Concept
archive	I-General_Concept
,	O
because	O
it	O
is	O
a	O
valid	O
shell	B-Language
script	I-Language
,	O
and	O
executing	O
it	O
will	O
recreate	O
the	O
files	O
.	O
</s>
<s>
To	O
extract	O
the	O
files	O
,	O
only	O
the	O
standard	O
Unix	B-Application
Bourne	B-Device
shell	I-Device
sh	O
is	O
usually	O
required	O
.	O
</s>
<s>
Note	O
that	O
the	O
shar	B-General_Concept
command	B-Application
is	O
not	O
specified	O
by	O
the	O
Single	O
Unix	B-Application
Specification	O
,	O
so	O
it	O
is	O
not	O
formally	O
a	O
component	O
of	O
Unix	B-Application
,	O
but	O
a	O
legacy	O
utility	O
.	O
</s>
<s>
While	O
the	O
shar	B-General_Concept
format	O
has	O
the	O
advantage	O
of	O
being	O
plain	O
text	O
,	O
it	O
poses	O
a	O
risk	O
due	O
to	O
being	O
executable	B-Application
;	O
for	O
this	O
reason	O
the	O
older	O
and	O
more	O
general	O
tar	B-Application
file	I-Application
format	I-Application
is	O
usually	O
preferred	O
even	O
for	O
transferring	O
text	O
files	O
.	O
</s>
<s>
GNU	B-Operating_System
provides	O
its	O
own	O
version	O
of	O
shar	B-General_Concept
in	O
the	O
GNU	B-Application
Sharutils	I-Application
collection	O
.	O
</s>
<s>
unshar	B-General_Concept
programs	O
have	O
been	O
written	O
for	O
other	O
operating	B-General_Concept
systems	I-General_Concept
but	O
are	O
not	O
always	O
reliable	O
;	O
shar	B-General_Concept
files	O
are	O
shell	B-Language
scripts	I-Language
and	O
can	O
theoretically	O
do	O
anything	O
that	O
a	O
shell	B-Language
script	I-Language
can	O
do	O
(	O
including	O
using	O
incompatible	O
features	O
of	O
enhanced	O
or	O
workalike	O
shells	O
)	O
,	O
limiting	O
their	O
utility	O
outside	O
the	O
Unix	B-Application
world	O
.	O
</s>
<s>
The	O
drawback	O
of	O
self-extracting	O
shell	B-Language
scripts	I-Language
(	O
any	O
kind	O
,	O
not	O
just	O
shar	B-General_Concept
)	O
is	O
that	O
they	O
may	O
rely	O
on	O
a	O
particular	O
implementation	O
of	O
programs	O
;	O
shell	B-General_Concept
archives	I-General_Concept
created	O
with	O
older	O
versions	O
of	O
makeself	O
,	O
for	O
example	O
,	O
the	O
original	O
Unreal	B-Operating_System
Tournament	I-Operating_System
for	O
Linux	O
installer	O
,	O
fails	O
to	O
run	O
on	O
bash	O
3.x	O
due	O
to	O
a	O
change	O
in	O
how	O
missing	O
arguments	O
to	O
trap	O
built-in	O
command	B-Application
are	O
handled	O
.	O
</s>
<s>
James	O
Gosling	O
is	O
credited	O
with	O
writing	O
the	O
first	O
version	O
of	O
the	O
shar	B-General_Concept
utility	O
in	O
1982	O
,	O
and	O
also	O
wrote	O
an	O
early	O
example	O
(	O
allegedly	O
1978-79	O
)	O
of	O
the	O
concept	O
in	O
the	O
form	O
of	O
this	O
simple	O
shell	B-Language
script	I-Language
:	O
</s>
<s>
The	O
following	O
variants	O
of	O
shar	B-General_Concept
are	O
known	O
:	O
</s>
<s>
shar	B-General_Concept
1.x	O
(	O
1982	O
)	O
by	O
Gosling	O
.	O
</s>
<s>
Public	O
domain	O
shell	B-Language
script	I-Language
.	O
</s>
<s>
Current	O
FreeBSD	B-Operating_System
shar	B-General_Concept
.	O
</s>
<s>
3-clause	O
BSD	O
license	O
,	O
shell	B-Language
script	I-Language
.	O
</s>
<s>
Public	O
domain	O
,	O
C	B-Language
program	I-Language
.	O
</s>
<s>
shar	B-General_Concept
3.49	O
(	O
1990	O
)	O
by	O
Richard	O
H	O
.	O
Gumpertz	O
.	O
</s>
<s>
Adds	O
uuencode	B-Device
support	O
.	O
</s>
<s>
Current	O
GNU	B-Application
sharutils	I-Application
.	O
</s>
<s>
GPLv3	O
,	O
C	B-Language
program	I-Language
.	O
</s>
<s>
C	B-Language
program	I-Language
.	O
</s>
<s>
cshar	O
(	O
1988	O
)	O
by	O
Rich	B-Application
Salz	I-Application
,	O
C	B-Language
program	I-Language
.	O
</s>
<s>
Likely	O
influenced	O
shar	B-General_Concept
3.49	O
.	O
</s>
<s>
ccshar	O
(	O
1996	O
)	O
,	O
a	O
modification	O
to	O
output	O
a	O
csh	B-Operating_System
script	O
instead	O
.	O
</s>
<s>
GNU	B-Operating_System
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>
<s>
A	O
version	O
of	O
the	O
same	O
concept	O
,	O
but	O
for	O
the	O
VMS	B-Operating_System
operating	I-Operating_System
system	I-Operating_System
,	O
was	O
written	O
in	O
1987	O
by	O
Michael	O
Bednarek	O
from	O
The	O
Melbourne	O
Institute	O
of	O
Applied	O
Economic	O
and	O
Social	O
Research	O
as	O
a	O
DCL	B-Operating_System
script	O
,	O
VMS_SHAR.COM	O
.	O
</s>
<s>
makeself	O
(	O
2001	O
)	O
is	O
a	O
shell	B-Language
script	I-Language
that	O
generates	O
self-extracting	O
tarballs	B-Application
(	O
,	O
)	O
using	O
the	O
same	O
shell	B-Language
script	I-Language
header	O
technique	O
.	O
</s>
<s>
Using	O
tar	B-Application
precludes	O
makeself	O
from	O
being	O
used	O
in	O
plain	O
text	O
directly	O
,	O
but	O
the	O
better	O
compression	O
and	O
other	O
functionalities	O
has	O
made	O
it	O
more	O
popular	O
in	O
the	O
21st	O
century	O
among	O
software	O
vendors	O
seeking	O
to	O
package	O
Linux	O
software	O
.	O
</s>
