Red Hat Bugzilla – Bug 443554
Add "s" option to boot single user mode from grub command line
Last modified: 2014-06-18 04:46:18 EDT
Description of problem: Historycally we can boot with single user mode from grub command line adding "s". But after changing to upstart, only "-s", "single" and "S" are allowed. Version-Release number of selected component (if applicable): event-compat-sysv-0.3.9-13.fc9.noarch How reproducible: always when type "s" Steps to Reproduce: 1. enter grub menu 2. append "s" to command line 3. Actual results: default runlevel (3 or 5) Expected results: single user mode (1) Additional info: Here is a proposed patch. --- /etc/event.d/rcS~ 2008-04-05 00:49:20.000000000 +0900 +++ /etc/event.d/rcS 2008-04-22 16:32:45.000000000 +0900 @@ -20,7 +20,7 @@ [ -z "$runlevel" ] && runlevel="3" for t in $(cat /proc/cmdline); do case $t in - -s|single|S) runlevel="S" ;; + -s|single|S|s) runlevel="S" ;; [1-9]) runlevel="$t" ;; esac done
I'm not sure why 's' worked before. From the init manpage: Init accepts the following flags: -s, S, single Single user mode boot. In this mode /etc/inittab is examined and the bootup rc scripts are usually run before the single user mode shell is started. From the code: if (!strcmp(argv[f], "single") || !strcmp(argv[f], "-s")) dfl_level = 'S'; So, I don't think 's' was ever really supported.
Aha, found it: if (dfl_level == 's') dfl_level = 'S'; Yay for undocumented features.
Which man page you are referring ? On F8, LANG=C man 8 init said Runlevel S or s bring the system to single user mode and do not require an /etc/inittab file. In single user mode, a root shell is opened on /dev/console. $ rpm -qf /usr/share/man/man8/init.8.gz sysvinit-2.86-18
Will be in 0.3.9-14.
Sorry. Please ignore Comment #3. And thank you for adding undocumented feature. I've been using this option for over 10 years. It's so thanksfull to keep compatibility.