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Don't ever change, baby

© February 2009 Anthony Lawrence

A comment at Controlling core files (Linux) set me thinking about change. You don't need to click on the link; I'll reproduce the comment and my reply here.

That post was written on March 14th, 2005. It described various methods of controlling core files in Linux, including some /proc settings that were fairly new at the time it was written and wouldn't be found in all distros. I haven't looked recently to see if there is anything new in that regard (I probably should), but it was accurate when written.

So there we are. This morning someone named ZhichangYu left this comment:

Really good guide! However It's a pity that it doesn't mention that /etc/sysctl.conf controls all settings under /proc/sys.

I really appreciate helpful comments. I had to smile a little at the "it's a pity" - I can't imagine that any serious damage could come from failing to mention that - but I do appreciate the fact that ZhichangYu was willing to take a moment to add something that might be useful to another reader. That's always helpful and I am always appreciative.

However, his comment also reminded me about change, so I added my own reply:

A pity?


I guess sysctl and sysctl.conf are fairly standard now but weren't when this was written. Not all distros used sysctl.conf then and I wouldn't bet my life that all do today.

I think it is probably true that sysctl.conf is a fairly safe assumption now, but more generally you should never assume that because you know something about one distro at one point in time that it applies to other distros or even that same distro at another point in time.

If you pawed through the thousands of posts here, you'd find lots of examples like that: things that were once true that aren't now, things that mention /proc but not sysctl, things that mention sysctl but not sysctl.conf, things that have changed, things that now don't work the way they did when the post was written - it's impossible for me to keep up with and that's why I REALLY APPRECIATE COMMENTS LIKE THIS.

Even when laced with pity :-)

This is hardly the only example. For example, if you read Shell Bashing from May 2001, you'd find an incorrect description of how .bashrc works on a current Linux system. It worked as described when that was written, but it doesn't work that way now. I've added a note to the page explaining that, but that's one page out of many thousands: things change.

The Skills Test pages here are rife with that sort of thing. When I notice something, I make a note or an addition, but I always leave the original information in place as a historical record that might help remind readers about the dangers of assumptions, especially with something as fast moving and as varied as Linux. A while back I added this warning to the beginning of the Linux tests:

February 2008: These tests are all badly in need of update. Some questions are incorrect because of changing technology and others just make no sense in today's IT world. I do intend to update these, but it's a big project..

A project that has been helped by numerous comments, of course.

I do look for this kind of thing. When I notice something has changed in the big world of Linux, I go searching here for posts that might need to be updated. I also just use random pages to find stuff that needs updating, but there is no way I'll find it all.

Change is going to happen. Information rots. Technology marches on. Please, please, PLEASE, if you see something that needs updating, leave a comment or shoot me an email. You'll be helping the next guy and we all appreciate it.

Got something to add? Send me email.

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-> Don't ever change, baby

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