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RUN LEVELS
Background
-Linux can boot
into various configurations (much like with what you get with Windows when
hitting F8 while booting)
-Linux has 6 boot
levels but outside of specialized situations, only levels 3 & 5 are useful
-Runlevel 3 boots
to a command prompt –this is the default Runlevel for most servers
-Runlevel 5 boots
to a GUI interface similar to Windows – this is the default Runlevel for most
workstations
Linux RunLevel Chart
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Runlevels
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Number
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Name
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Login
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Network
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Filesystems
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0
|
Halt
|
|
|
|
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1
|
Single
user
(Very Useful for Troubleshooting)
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Textual
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Down
|
Mounted
|
|
2
|
Multiuser
without NFS
(Network File System)
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Textual
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Up
(partially)
|
Mounted
|
|
3
|
Multiuser
(Standard boot level for servers) |
Textual
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Up
|
Mounted
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4
|
User
defined
|
|
|
|
|
5
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Multiuser
with X Windows/GUI
(Standard boot level for desktops) |
Graphical
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Up
|
Mounted
|
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6
|
Reboot
|
|
|
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How to change a Run Level
1. Make sure you
are logged in as root
2. init runlevel
i.e.
init 6
reboot the system
How to change The Default Run Level
NOTE: Be VERY care with this – DO NOT
set your run levels to 6 (forever rebooting) or 0 (your machine halts every
time you try and start it.
Steps:
1.
vi /etc/inittab
2.
Look for a line the ends with initdefault
i.e.:
id:3:initdefault:
3.
Change the number. Unless you are troubleshooting you should only use a value
of 3 or 5 in this line
4.
Save
5.
Reboot system to test.
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