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Cronic - A cure for Cron's chronic email problem

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Re: Cronic - A cure for Cron's chronic email problem

#31

Post by zarify »

there wrote: post #5

In a dozen or so years of administrating many different Unix machines, I've never had cron email be a problem and I get a few (useful) emails from various cron scripts every day. This interacts badly with many unix commands, which often send status info to standard out. Some commands have a quiet options, but that can turn off all error output too. Maybe it's that I've mostly been administrating BSD machines, and so…

I remember getting an angry email from someone because of this when I was back at uni, had just finishing installing a linux box at home, but hadn't finished configuring everything. I went to bed while it was busily running cron jobs throughout the remainder of the night and emailing the output to someone else who had the same username at my ISP as the local one I'd set up on the machine. I don't think he saw the funny side of it sadly.

Re: Cronic - A cure for Cron's chronic email problem

#32

Post by _swa8 »

joeyh wrote: post #3

I added a simplified version of chronic to moreutils a while back. http://joeyh.name/code/moreutils (also packaged in some major linux distros)

moreutils is a nice package to have installed in any case. For example, sponge is very handy at times.

(Disclaimer: I wrote isutf8, which is included in moreutils.)

Re: Cronic - A cure for Cron's chronic email problem

#33

Post by _swa8 »

zobzu wrote: post #12
there wrote: post #5

In a dozen or so years of administrating many different Unix machines, I've never had cron email be a problem and I get a few (useful) emails from various cron scripts every day. This interacts badly with many unix commands, which often send status info to standard out. Some commands have a quiet options, but that can turn off all error output too. Maybe it's that I've mostly been administrating BSD machines, and so…

I don't quite think that its a "gnuism" to do that. They generally take a --color option which of course is off by default. They did sometimes put the license everytime, a long time ago, but I don't see that anymore unless you ask the version or help.

GNU programs that show a license and copyright information at startup do so when used interactively, not when in batch mode. For example:

echo 1 + 2 | bc

That doesn't produce anything except "3", even with GNU bc.

Re: Cronic - A cure for Cron's chronic email problem

#34

Post by _swa8 »

ciupicri wrote: post #10
emmelaich wrote: post #7

Earlier quoted context omitted.

I'm guessing ls which colors; perhaps keychain (very colorful output). I see less of the license stuff these days but no doubt there's a few around.

On Red Hat based systems, ls is an alias for ls --color=auto which means that colors are used only on terminals, not pipes or files.

Debian has this as well. I do "unalias -a" whenever I log into an account I haven't configured to my liking yet (I want no ls coloring, but I do want a bash prompt in boldface).

Re: Cronic - A cure for Cron's chronic email problem

#35

Post by regularfry »

enneff wrote: post #13
there wrote: post #5

In a dozen or so years of administrating many different Unix machines, I've never had cron email be a problem and I get a few (useful) emails from various cron scripts every day. This interacts badly with many unix commands, which often send status info to standard out. Some commands have a quiet options, but that can turn off all error output too. Maybe it's that I've mostly been administrating BSD machines, and so…

You're bang on. Commands should do what you tell them and say nothing unless something unexpected occurred. (or, if you asked them to say something) Cron isn't broken. It's chatty programs that are broken.

So you can scream at the darkness or light a candle. It doesn't matter which is broken if you can only fix one.

Re: Cronic - A cure for Cron's chronic email problem

#36

Post by reidrac »

SourPatch wrote: post #15

There are many different cron implementations. Do none of them check exit status?

All of them.

cron sends a mail if: a) there's output (stdout or stderr) or b) the command exit code isn't 0.

So I really don't understand the post when it says "Now when your cron job fails, you will never know about it.".

Well, if you script fails and still returns 0, your script is broken. If you script outputs stuff when it's not supposed to, it can't run from cron.

Re: Cronic - A cure for Cron's chronic email problem

#37

Post by ibotty »

kbronson wrote: post #26

I like how the web page switches to two-column layout if it has enough screen space.

now that's nice. i did not notice, as it depends on javascript. but very nice! something to copy i guess ;).

(that alone is worth the article. the "real" content is just misunderstanding of unix i'm afraid)

Re: Cronic - A cure for Cron's chronic email problem

#39

Post by nodata »

Dobbs wrote: post #24
dfrankow wrote: post #8

I have this problem, I only want to be emailed upon failure. However, the crontab of the account is shared by several different jobs run by different people, and I don't have control over that. Perhaps I could set the email in the crontab line? * * * * * MAILTO=me@example.com blahscript.sh

blahscript.sh | mail -s "Subject" me@example.com

mail -E

Re: Cronic - A cure for Cron's chronic email problem

#40

Post by asjo »

dfrankow wrote: post #8

I have this problem, I only want to be emailed upon failure. However, the crontab of the account is shared by several different jobs run by different people, and I don't have control over that. Perhaps I could set the email in the crontab line? * * * * * MAILTO=me@example.com blahscript.sh

You can set MAILTO by itself between the job lines in the crontab; e.g.:

    MAILTO=user1@example.com
    * */10 * * * script1
    5 * * * * script2
    MAILTO=user2@example.com
    * * * * * script3
Any output from script1 and 2 will be sent to user1 and any from script3 to user2.
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