<s>
Single-user	B-Operating_System
mode	I-Operating_System
is	O
a	O
mode	O
in	O
which	O
a	O
multiuser	B-Operating_System
computer	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
boots	B-Operating_System
into	O
a	O
single	O
superuser	B-Application
.	O
</s>
<s>
It	O
is	O
mainly	O
used	O
for	O
maintenance	O
of	O
multi-user	B-Operating_System
environments	O
such	O
as	O
network	O
servers	O
.	O
</s>
<s>
Some	O
tasks	O
may	O
require	O
exclusive	O
access	O
to	O
shared	B-General_Concept
resources	I-General_Concept
,	O
for	O
example	O
running	O
fsck	B-Device
on	O
a	O
network	B-General_Concept
share	I-General_Concept
.	O
</s>
<s>
On	O
some	O
systems	O
a	O
lost	O
superuser	B-Application
password	O
can	O
be	O
changed	O
by	O
switching	O
to	O
single-user	B-Operating_System
mode	I-Operating_System
,	O
but	O
not	O
asking	O
for	O
the	O
password	O
in	O
such	O
circumstances	O
is	O
viewed	O
as	O
a	O
security	O
vulnerability	O
.	O
</s>
<s>
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
provide	O
single-user	B-Operating_System
mode	I-Operating_System
functionality	O
either	O
through	O
the	O
System	O
V-style	O
runlevels	B-Device
,	O
BSD-style	O
boot-loader	O
options	O
,	O
or	O
other	O
boot-time	O
options	O
.	O
</s>
<s>
The	O
run-level	O
is	O
usually	O
changed	O
using	O
the	O
init	O
command	O
,	O
runlevel	B-Device
1	O
or	O
S	O
will	O
boot	B-Operating_System
into	O
single-user	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
Boot-loader	O
options	O
can	O
be	O
changed	O
during	O
startup	O
before	O
the	O
execution	O
of	O
the	O
kernel	O
.	O
</s>
<s>
In	O
FreeBSD	B-Operating_System
and	O
DragonFly	B-Application
BSD	I-Application
it	O
can	O
be	O
changed	O
before	O
rebooting	O
the	O
system	O
with	O
the	O
command	O
nextboot	O
-o	O
"	O
-s	O
"	O
-k	O
kernel	O
,	O
and	O
its	O
bootloader	O
offers	O
the	O
option	O
on	O
bootup	B-Operating_System
to	O
start	O
in	O
single-user	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
In	O
Solaris	B-Application
the	O
command	O
reboot	O
--	O
-s	O
will	O
cause	O
a	O
reboot	O
into	O
single-user	B-Operating_System
mode	I-Operating_System
.	O
</s>
<s>
macOS	B-Application
users	O
can	O
accomplish	O
this	O
by	O
holding	O
down	O
after	O
powering	O
the	O
system	O
.	O
</s>
<s>
The	O
user	O
may	O
be	O
required	O
to	O
enter	O
a	O
password	O
set	O
in	O
the	O
firmware	B-Application
.	O
</s>
<s>
In	O
OS	B-Operating_System
X	I-Operating_System
El	I-Operating_System
Capitan	I-Operating_System
and	O
later	O
releases	O
of	O
macOS	B-Application
,	O
the	O
mode	O
can	O
be	O
reversed	O
to	O
single-user	B-Operating_System
mode	I-Operating_System
with	O
the	O
command	O
sudo	O
launchctl	O
reboot	O
userspace	O
-s	O
in	O
Terminal	O
,	O
and	O
the	O
system	O
can	O
be	O
fully	O
rebooted	O
in	O
single-user	B-Operating_System
mode	I-Operating_System
with	O
the	O
command	O
sudo	O
launchctl	O
reboot	O
system	O
-s	O
.	O
Single-user	B-Operating_System
mode	I-Operating_System
is	O
different	O
from	O
a	O
safe	B-Operating_System
mode	I-Operating_System
boot	B-Operating_System
in	O
that	O
the	O
system	O
goes	O
directly	O
to	O
the	O
console	O
instead	O
of	O
starting	O
up	O
the	O
core	O
elements	O
of	O
macOS	B-Application
(	O
items	O
in	O
/System/Library/	O
,	O
ignoring	O
/Library/	O
,	O
~	O
/Library/	O
,	O
et	O
al	O
.	O
)	O
.	O
</s>
<s>
From	O
there	O
users	O
are	O
encouraged	O
by	O
a	O
prompt	O
to	O
run	O
fsck	B-Device
or	O
other	O
command	B-Application
line	I-Application
utilities	O
as	O
needed	O
(	O
or	O
installed	O
)	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
provides	O
Recovery	O
Console	O
,	O
Last	O
Known	O
Good	O
Configuration	O
,	O
Safe	B-Operating_System
Mode	I-Operating_System
and	O
recently	O
Windows	O
Recovery	O
Environment	O
as	O
standard	O
recovery	O
means	O
.	O
</s>
<s>
Also	O
,	O
bootable	B-Operating_System
BartPE-based	O
third-party	O
recovery	O
discs	O
are	O
available	O
.	O
</s>
<s>
Recovery	O
Console	O
and	O
recovery	O
discs	O
are	O
different	O
from	O
single-user	B-Operating_System
modes	I-Operating_System
in	O
other	O
operating	B-General_Concept
systems	I-General_Concept
because	O
they	O
are	O
independent	O
of	O
the	O
maintained	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
