On Wed, Mar 6, 2013 at 9:02 AM, W. Trevor King <[email protected]> wrote: > From: "W. Trevor King" <[email protected]> > > Starting a "login" version of Bash via `su` is tricky. The naive: > > su - ${first_user} -c startx > > fails because `su - ...` clears a number of environment variables (so > the prefixed `source /etc/profile` doesn't accomplish anything), but > Bash isn't started with the `--login` option, so it doesn't source > /etc/profile internally. From bash(1): > > A login shell is one whose first character of argument zero is a -, > or one started with the --login option. > ... > An interactive shell is one started without non-option arguments and > without the -c option whose standard input and error are both > connected to terminals (as determined by isatty(3)), or one started > with the -i option... > ... > When bash is invoked as an interactive login shell, or as a > non-interactive shell with the --login option, it first reads and > executes commands from the file /etc/profile, if that file exists. > After reading that file, it looks for ~/.bash_profile, > ~/.bash_login, and ~/.profile, in that order, and reads and executes > commands from the first one that exists and is readable. The > --noprofile option may be used when the shell is started to inhibit > this behavior. > > In order to get the login-style profile loading with a non-interactive > `su` invocation, you need to use something like: > > echo "${command}" | su - "${user}" > > This starts a login shell and pipes the command in via stdin, which > seems to fake Bash into thinking its running from an interactive > terminal. Not the most elegant, but the other implementations I can > think of are even worse: > > su - "${user}" -c "bash --login -c ${command}" > su - "${user}" -c 'source /etc/profile && > (source .bash_profile || ...) && ${command}" > > The old expression was broken anyway due to unescaped ampersands in > the sed expression. From sed(1): > > s/regexp/replacement/ > Attempt to match regexp against the pattern space. If successful, > replace that portion matched with replacement. The replacement > may contain the special character & to refer to that portion of > the pattern space which matched, and the special escapes \1 > through \9 to refer to the corresponding matching sub-expressions > in the regexp. > > This means that the old expression (with unescaped ampersands) lead > to: > > source /etc/profile ##STARTX##STARTX su - ${first_user} -c startx > > with ${first_user} expanded. This commented out startx, so it was > never run. > --- > targets/support/livecdfs-update.sh | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/targets/support/livecdfs-update.sh > b/targets/support/livecdfs-update.sh > index 77d694e..0ac41dd 100644 > --- a/targets/support/livecdfs-update.sh > +++ b/targets/support/livecdfs-update.sh > @@ -388,9 +388,7 @@ esac > # We want the first user to be used when auto-starting X > if [ -e /etc/startx ] > then > - sed -i \ > - "s:##STARTX:source /etc/profile && su - ${first_user} -c > startx:" \ > - /root/.bashrc > + sed -i "s:##STARTX:echo startx | su - '${first_user}':" /root/.bashrc > fi > > if [ -e /lib/rcscripts/addons/udev-start.sh ] > -- > 1.8.2.rc0.16.g20a599e > >
This doesn't apply after PATCH 1/2 in this series. Probably why the first PATCH wasn't labeled as 1/2. Want to confirm what you want to do here?
