<s>
Safe	B-Operating_System
mode	I-Operating_System
is	O
a	O
diagnostic	B-Operating_System
mode	I-Operating_System
of	O
a	O
computer	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
(	O
OS	O
)	O
.	O
</s>
<s>
It	O
can	O
also	O
refer	O
to	O
a	O
mode	O
of	O
operation	O
by	O
application	B-Application
software	I-Application
.	O
</s>
<s>
Safe	B-Operating_System
mode	I-Operating_System
is	O
intended	O
to	O
help	O
fix	O
most	O
,	O
if	O
not	O
all	O
,	O
problems	O
within	O
an	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
,	O
macOS	B-Application
,	O
Android	B-Application
and	O
Linux	B-Application
distributions	O
such	O
as	O
Ubuntu	B-Operating_System
and	O
Linux	B-Application
Mint	I-Application
are	O
examples	O
of	O
contemporary	O
operating	B-General_Concept
systems	I-General_Concept
that	O
implement	O
a	O
safe	B-Operating_System
mode	I-Operating_System
(	O
called	O
"	O
Safe	B-Operating_System
Boot	I-Operating_System
"	O
in	O
macOS	B-Application
)	O
as	O
well	O
as	O
other	O
complex	O
electronic	O
devices	B-Device
.	O
</s>
<s>
In	O
safe	B-Operating_System
mode	I-Operating_System
,	O
an	O
operating	B-General_Concept
system	I-General_Concept
has	O
reduced	O
functionality	O
,	O
but	O
the	O
task	O
of	O
isolating	O
problems	O
is	O
easier	O
since	O
many	O
non-core	O
components	O
are	O
disabled	O
,	O
such	O
as	O
sound	O
.	O
</s>
<s>
An	O
installation	O
that	O
will	O
only	O
boot	B-Operating_System
into	O
safe	B-Operating_System
mode	I-Operating_System
typically	O
has	O
a	O
major	O
problem	O
,	O
such	O
as	O
disk	O
corruption	O
or	O
the	O
installation	O
of	O
poorly-configured	O
software	O
that	O
prevents	O
the	O
operating	B-General_Concept
system	I-General_Concept
from	O
successfully	O
booting	B-Operating_System
into	O
its	O
normal	O
operating	O
mode	O
.	O
</s>
<s>
Though	O
it	O
varies	O
by	O
operating	B-General_Concept
system	I-General_Concept
,	O
safe	B-Operating_System
mode	I-Operating_System
typically	O
loads	O
only	O
essential	O
executable	O
modules	O
and	O
disables	O
devices	B-Device
except	O
for	O
those	O
necessary	O
to	O
display	O
information	O
and	O
accept	O
input	O
.	O
</s>
<s>
It	O
can	O
also	O
take	O
the	O
form	O
of	O
a	O
parallel	O
"	O
miniature	O
"	O
operating	B-General_Concept
system	I-General_Concept
that	O
has	O
no	O
configuration	O
information	O
shared	O
with	O
the	O
normal	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
on	O
Microsoft	B-Application
Windows	I-Application
,	O
the	O
user	O
can	O
also	O
choose	O
to	O
boot	B-Operating_System
to	O
the	O
Recovery	O
Console	O
,	O
a	O
small	O
text-based	O
troubleshooting	O
mode	O
kept	O
separate	O
from	O
the	O
main	O
operating	B-General_Concept
system	I-General_Concept
(	O
which	O
can	O
also	O
be	O
accessed	O
by	O
booting	B-Operating_System
the	O
install	O
CD	O
)	O
or	O
to	O
various	O
"	O
safe	B-Operating_System
mode	I-Operating_System
"	O
options	O
that	O
run	O
the	O
dysfunctional	O
OS	O
but	O
with	O
features	O
,	O
such	O
as	O
video	O
drivers	O
,	O
audio	O
,	O
and	O
networking	B-Architecture
,	O
disabled	O
.	O
</s>
<s>
Safe	B-Operating_System
mode	I-Operating_System
typically	O
provides	O
access	O
to	O
utility	O
and	O
diagnostic	O
programs	O
so	O
a	O
user	O
can	O
troubleshoot	O
what	O
is	O
preventing	O
the	O
operating	B-General_Concept
system	I-General_Concept
from	O
working	O
normally	O
.	O
</s>
<s>
Safe	B-Operating_System
mode	I-Operating_System
is	O
intended	O
for	O
maintenance	O
,	O
not	O
functionality	O
,	O
and	O
it	O
provides	O
minimal	O
access	O
to	O
features	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
 '	O
safe	B-Operating_System
mode	I-Operating_System
(	O
for	O
7/Vista	O
/XP	O
/2000/ME/98/95	O
)	O
is	O
accessed	O
by	O
pressing	O
the	O
F8	B-Application
key	I-Application
as	O
the	O
operating	B-General_Concept
system	I-General_Concept
boots	O
.	O
</s>
<s>
Also	O
,	O
in	O
a	O
multi-boot	O
environment	O
with	O
multiple	O
versions	O
of	O
Windows	O
installed	O
side	O
by	O
side	O
,	O
the	O
F8	B-Application
key	I-Application
can	O
be	O
pressed	O
at	O
the	O
OS	O
selector	O
prompt	O
to	O
get	O
to	O
safe	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
An	O
equivalently	O
minimal	O
setting	O
in	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
is	O
single-user	B-Operating_System
mode	I-Operating_System
,	O
in	O
which	O
daemons	B-Operating_System
and	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
are	O
not	O
started	O
,	O
and	O
only	O
the	O
root	B-Application
user	I-Application
can	O
log	O
in	O
.	O
</s>
<s>
In	O
macOS	B-Application
holding	O
the	O
shift	B-Device
key	I-Device
after	O
powering	O
up	O
activates	O
Safe	B-Operating_System
Boot	I-Operating_System
that	O
has	O
background	O
maintenance	O
features	O
(	O
Besides	O
the	O
mode	O
selection	O
,	O
it	O
runs	O
a	O
file	O
system	O
repair	O
,	O
and	O
in	O
Mac	B-Application
OS	I-Application
10.4	O
,	O
it	O
disables	O
all	O
fonts	O
other	O
than	O
those	O
in	O
/System/Library/Fonts	O
,	O
moves	O
to	O
the	O
Trash	O
all	O
font	O
caches	O
normally	O
stored	O
in	O
/Library/Caches/com.apple.ATS/	O
( uid	O
)	O
/	O
,	O
where	O
(	O
uid	O
)	O
is	O
a	O
user	O
ID	O
number	O
such	O
as	O
501	O
,	O
and	O
disables	O
all	O
startup	O
items	O
and	O
any	O
Login	O
Items	O
)	O
.	O
</s>
<s>
Unlike	O
in	O
Windows	O
where	O
safe	B-Operating_System
mode	I-Operating_System
with	O
networking	B-Architecture
is	O
disabled	O
by	O
default	O
and	O
requires	O
using	O
a	O
safe	B-Operating_System
mode	I-Operating_System
with	O
networking	B-Architecture
enabled	O
,	O
in	O
the	O
macOS	B-Application
Safe	B-Operating_System
Boot	I-Operating_System
always	O
includes	O
networking	B-Architecture
.	O
</s>
<s>
On	O
the	O
Classic	B-Application
Mac	I-Application
OS	I-Application
versions	O
6	O
,	O
7	B-Device
,	O
8	O
,	O
and	O
9	O
,	O
a	O
similar	O
mode	O
to	O
the	O
Unix	O
root	O
is	O
achieved	O
by	O
holding	O
down	O
the	O
shift	B-Device
key	I-Device
while	O
booting	B-Operating_System
,	O
which	O
starts	O
the	O
system	O
without	O
extensions	B-Operating_System
.	O
</s>
<s>
The	O
way	O
that	O
safe	B-Operating_System
mode	I-Operating_System
in	O
Android	B-Application
can	O
be	O
activated	O
differs	O
per	O
vendor	O
.	O
</s>
<s>
Safe	B-Operating_System
mode	I-Operating_System
can	O
be	O
disabled	O
by	O
rebooting	O
the	O
device	O
.	O
</s>
<s>
When	O
you	O
reboot	O
into	O
safe	B-Operating_System
mode	I-Operating_System
in	O
Android	B-Application
,	O
downloaded	O
apps	O
and	O
widgets	O
are	O
automatically	O
disabled	O
,	O
but	O
built-in	O
apps	O
remain	O
available	O
.	O
</s>
<s>
A	O
watermark	O
in	O
the	O
bottom-left	O
corner	O
also	O
appears	O
if	O
you	O
're	O
booted	O
to	O
either	O
normal	O
or	O
safe	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
Some	O
devices	B-Device
also	O
turn	O
their	O
radios	O
off	O
automatically	O
upon	O
booting	B-Operating_System
into	O
safe	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
Application	B-Application
software	I-Application
sometimes	O
offers	O
a	O
safe	B-Operating_System
mode	I-Operating_System
as	O
well	O
.	O
</s>
<s>
In	O
the	O
PHP	B-Application
interpreter	I-Application
,	O
prior	O
to	O
version	O
5.4	O
,	O
safe	B-Operating_System
mode	I-Operating_System
offers	O
stricter	O
security	O
measures	O
.	O
</s>
<s>
The	B-Application
Glasgow	I-Application
Haskell	I-Application
Compiler	I-Application
from	O
version	O
7.2	O
offers	O
"	O
Safe	O
Haskell	O
"	O
mode	O
,	O
restricting	O
usage	O
of	O
functions	O
such	O
as	O
unsafePerformIO	O
.	O
</s>
<s>
Mozilla	B-Application
Firefox	I-Application
's	I-Application
safe	B-Operating_System
mode	I-Operating_System
allows	O
the	O
user	O
to	O
remove	O
extensions	B-Operating_System
which	O
may	O
be	O
preventing	O
the	O
browser	O
from	O
loading	O
.	O
</s>
<s>
Internet	B-Application
Explorer	I-Application
can	O
run	O
in	O
"	O
No	O
Add-Ons	B-Operating_System
"	O
mode	O
and	O
Protected	O
Mode	O
.	O
</s>
<s>
Cydia	B-Device
's	O
MobileSubstrate	O
also	O
has	O
a	O
safe	B-Operating_System
mode	I-Operating_System
that	O
allows	O
the	O
user	O
to	O
uninstall	O
tweaks	B-Application
and	I-Application
extensions	I-Application
that	O
may	O
crash	O
the	O
SpringBoard	O
.	O
</s>
