Difference between run levels 1 and S

difference between run levels 1 and S

S:Single-user, booted to system console only, with only root filesystem mounted (as read-only)

s:Single user, identical to S except the current terminal acts as the system console

1:Single-user with local filesystems mounted (read-write)

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so far, i've established that {S,s} is *not* equivalent to 1,since run level 1 does consult /etc/inittab, while {S,s} does not.and, as far as i can tell, you're supposed to go to single-user modeby going to run level 1.  as a test, try "init s" and see whathappens.  very different from "init 1" -- with "init s", none of/etc/rc1.d is consulted, so services are *not* killed.

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 S - true single user mode usually drops you into a minimal root shell 1 - Administrative mode, you get a standard login request before access 2 - Multi-user without TCP/IP networking -- could use serial ports for other logins 3 - Multi-user with TCP/IP networking and text  4 - To be determined by the system owner 5 - Multi-User with TCP/IP networking and graphic console  6 - reboot 0 - shutdown and power down