> -----Original Message----- > From: David Chisnall [mailto:thera...@freebsd.org] > Sent: Sunday, February 23, 2014 10:18 AM > To: Allan Jude > Cc: FreeBSD Current > Subject: Re: libinit idea > > On 23 Feb 2014, at 18:11, Allan Jude <free...@allanjude.com> wrote: > > > sysrc solves this nicely, it is in base now, and is great for > > programmatically adding, removing and changing lines in rc.conf style > > files. It is also in ports for older versions of FreeBSD where it is > > not in base. > > The problem is, there is no such thing as an rc.conf style file. rc.conf is just a > shell script. If you only edit it with sysrc, or you are careful to preserve the > structure, then it's fine.
Actually, sysrc is well aware that rc.conf is a shell script and sysrc will actually make certain that structure is preserved (regardless of whether you've placed shell code in rc.conf or not). > There is absolutely nothing stopping you, however, > from writing arbitrarily complex shell scripts inside rc.conf. Sure, it's a terrible > idea to do so, but when has that ever stopped anyone? > When sysrc is told to make a change, it first finds where it needs to make that change (/etc/rc.conf or /etc/rc.conf.local or one of other paths mentioned in rc_conf_files setting), it will refuse to edit the file *IF* the file doesn't first (before editing) pass a shell syntax check (using "sh -n FILE"). After making the changes in a temporarily file (produced with mktemp(1)), it again performs yet another syntax check (also using "sh -n FILE") to make sure that it continues to yield clean syntax. On top of that, it makes certain not to muck with dynamic assignments. So it will leave-alone an assignment such as "foo=$( bar )" if told to edit the variable foo -- instead opting to add a foo=newvalue after the dynamic assignment (logic is simple... sysrc wasn't responsible for putting that dynamic assignment in, so it is going to leave it as-is and put the new [static] assignment further below. So Allan was absolutely correct in stating that sysrc is for editing "rc.conf style" files -- shell scripts really. In essence, sysrc is actually a shell script modifying utility that takes extreme special care to rely on the fact that rc.conf *is* a shell script. > An rc-replacement could enforce this by only accepting purely declarative files > for configuration, guaranteeing that if they were syntactically valid they would > also be machine editable, no matter what the user does to them. > sysrc does this for you. -- Devin _____________ The information contained in this message is proprietary and/or confidential. If you are not the intended recipient, please: (i) delete the message and all copies; (ii) do not disclose, distribute or use the message in any manner; and (iii) notify the sender immediately. In addition, please be aware that any message addressed to our domain is subject to archiving and review by persons other than the intended recipient. Thank you. _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
