971 lines
20 KiB
HTML
971 lines
20 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
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<HTML
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><HEAD
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><TITLE
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>Frequently Asked Questions</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
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REL="HOME"
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TITLE="Documentation de fcron"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Using fcron ..."
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HREF="using-fcron.html"><LINK
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REL="PREVIOUS"
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TITLE="fcrondyn"
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HREF="fcrondyn.1.html"><LINK
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REL="NEXT"
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TITLE="GNU GENERAL PUBLIC LICENSE"
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HREF="gpl.html"></HEAD
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><BODY
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CLASS="SECT1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="40%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="LEGALNOTICE.html"
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>Copyright</A
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> © 2000-2014 <A
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HREF="mailto:fcron@free.fr"
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>Thibault Godouet</A
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></TD
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><TD
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WIDTH="20%"
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ALIGN="center"
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VALIGN="top"
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>Fcron 3.2.0 </TD
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><TD
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WIDTH="40%"
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ALIGN="right"
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VALIGN="top"
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>Web page : <A
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HREF="http://fcron.free.fr"
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>http://fcron.free.fr</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Documentation de fcron</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="fcrondyn.1.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 2. Using fcron ...</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="gpl.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECT1"
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><H1
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CLASS="SECT1"
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><A
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NAME="FAQ"
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>2.2. Frequently Asked Questions</A
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></H1
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><P
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>This FAQ intends to complement the man pages by following a more
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practical approach.</P
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><P
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>If you think a QA should be added, please mail me it!</P
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><DIV
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CLASS="QANDASET"
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><DL
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><DT
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>2.2.1. <A
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HREF="faq.html#AEN2789"
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>How does fcron handle system clock adjustments?</A
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></DT
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><DT
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>2.2.2. <A
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HREF="faq.html#AEN2799"
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>How does fcron handle daylight saving time changes?</A
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></DT
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><DT
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>2.2.3. <A
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HREF="faq.html#AEN2806"
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>What about fcron and software suspend
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(aka. suspend to RAM, to disk)?</A
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></DT
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><DT
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>2.2.4. <A
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HREF="faq.html#AEN2813"
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>How can I prevent fcrontab from considering the first
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"word" of my command line as a user name i.e. "runas(word)"?</A
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></DT
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><DT
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>2.2.5. <A
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HREF="faq.html#AEN2820"
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> I have a job which usually terminates with a non-zero status. When it
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does, I receive a mail with the exit status even if the command had no output.
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How can I avoid the mail?</A
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></DT
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><DT
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>2.2.6. <A
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HREF="faq.html#AEN2826"
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>What does "loadavg" mean anyway?</A
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></DT
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><DT
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>2.2.7. <A
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HREF="faq.html#AEN2834"
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>How can I use fcrontab in scripts?</A
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></DT
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><DT
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>2.2.8. <A
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HREF="faq.html#AEN2847"
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>Can I use fcron from time to time, for instance in a
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script?</A
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></DT
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><DT
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>2.2.9. <A
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HREF="faq.html#AEN2886"
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>Can I run fcron without root's privileges?</A
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></DT
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><DT
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>2.2.10. <A
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HREF="faq.html#AEN2913"
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>Has fcron some incompatibilities with Vixie cron?</A
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></DT
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><DT
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>2.2.11. <A
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HREF="faq.html#AEN2922"
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>How can I emulate an anacron entry?</A
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></DT
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></DL
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN2789"
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></A
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><H3
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>2.2.1. How does fcron handle system clock adjustments?</H3
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></P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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> </B
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> First, you must understand that fcron determines, for each job, its next
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time and date of execution. It then determines which of those jobs would be the
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next to run and then, sleeps until that job should be run. In other words, fcron
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doesn't wake up like Vixie cron each minute to check all job in case one should
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be run ... and it avoids some problems associated with clock adjusts.</P
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><P
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> This means that if the new time value is set into the past, fcron won't
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run a particular job again. For instance, suppose the real time and system clock
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are 3:00, so the next job cannot be scheduled to run before 3:00, as it would
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have already been run and re-scheduled.</P
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><P
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> First, suppose you set your system clock into the past, say to 2:00,
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Presuming that the last run was shortly before 3:00. then fcron will sleep until
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the next job should be executed. The execution time for a job is determined by
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identifying the last time that the job ran and computing the next scheduled
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time. This means that the next scheduled time must be on or after 3:01.
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Therefore, in this example, fcron will not run a job for at least one
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hour.</P
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><P
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> Next, if you set the system time into the future, say to 4:00, fcron will
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run every job scheduled between the old and the new time value once, regardless
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of how many times it would have been scheduled. When fcron wakes up to run a job
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after the time value has changed, it runs all the jobs which should have run
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during the interval because they are scheduled to run in a past time.</P
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><P
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> As special case is when "@xxx" style scheduling rules are involved, you
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must consider the "adjustment-interval". The "adjustment-interval" is the time
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difference between the original system time and the new system time. The concerned
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jobs will run at "adjust-interval" too
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early or too late depending of the nature of the adjust.</P
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><P
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> To conclude, fcron behaves quite well for small clock adjusts. Each job
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which should have run does so once, but not exactly at the correct time as if
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the job were scheduled within the adjustment interval. But, if you have to make
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a big change in the time and date, you should probably reset all the scheduled
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"nextexe" by running "fcrontab -z" on all the fcrontabs.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
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><P
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><A
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NAME="AEN2799"
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></A
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><H3
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>2.2.2. How does fcron handle daylight saving time changes?</H3
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></P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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> </B
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>There are two types of daylight saving time change:
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the remove-one-hour change (for instance, "at 3:00, it will be 2:00"),
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and the add-one-hour one (for instance, "at 2:00, it will be 3:00").
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In both cases, fcron will run the job only once (more precisely, it won't
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run the job twice as many as it should have).</P
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><P
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>In the first case, the official time changes as follow
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(in order of real chronological time): [x, 2:00] -> i1: [2:00, 3:00]
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-> i2: [2:00, 3:00] -> [3:00, y]. i1 and i2 are the names of the two
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intervals [2:00, 3:00]. For this kind of DST change, a job which should
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run between 2:00 and 3:00 will run either in i1 or in i2, but not both.
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Consequently, a job scheduled to run every day at 2:30 (for instance)
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will be run only once. There is no way for a user to know if the job will
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be run in i1 or i2.</P
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><P
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>In the second case, there is a gap in time:
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the official time changes as follow (in order of real chronological time):
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[x, 2:00] -> [3:00, y]. A job scheduled between 2:00 and 3:00 will get
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run once, and only once, even if it should have been run several times.
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For instance, a job which should have run every 10 minutes will run only
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once, not 6 times, between 1:59 and 3:01. A job scheduled to run at
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2:xx will run at 3:xx. For instance, if a job is scheduled to run
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every day at 2:30, it will run at 3:30 the day of this kind of DST change.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
|
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><P
|
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><A
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NAME="AEN2806"
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></A
|
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><H3
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>2.2.3. What about fcron and software suspend
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(aka. suspend to RAM, to disk)?</H3
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></P
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></DIV
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><DIV
|
|
CLASS="ANSWER"
|
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><P
|
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><B
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> </B
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>We suppose here that you are using swsusp and the hibernate
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script to do a "suspend to disk", but it should be similar
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with other methods.</P
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><P
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>When you switch on your computer after a suspend to disk,
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the system time will be incorrect, and will then be corrected
|
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by the hibernate script. Before it is corrected, fcron may
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compute the time and date of the next execution of a job:
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the computation would then be incorrect (please see the entry
|
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about system clock adjustment in the present FAQ).</P
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><P
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>So you should have the hibernate script stop fcron before
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the suspend, and then restart it when the system is switched on,
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ie. put a line like "RestartServices fcron" in your hibernate.conf
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file. That way, the system time will always be correct when
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fcron runs (assuming that fcron is started after the system time
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is corrected).</P
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></DIV
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></DIV
|
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><DIV
|
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CLASS="QANDAENTRY"
|
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><DIV
|
|
CLASS="QUESTION"
|
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><P
|
|
><A
|
|
NAME="AEN2813"
|
|
></A
|
|
><H3
|
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>2.2.4. How can I prevent fcrontab from considering the first
|
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"word" of my command line as a user name i.e. "runas(word)"?</H3
|
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></P
|
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></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
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><P
|
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><B
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> </B
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> Suppose you have an user called "echo" (weird idea ... :)) ). If you use
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the line '* * * * * echo "Hello!"' in root's fcrontab, "echo" will be
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interpreted as "runas(echo)".</P
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><P
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>To suppress that, put your command in quotes:
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>* * * * * 'echo "Hello!"'</PRE
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></TD
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></TR
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></TABLE
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> will work as
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expected as quotes are allowed for the shell command but not for the user
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name.</P
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
|
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><P
|
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><A
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NAME="AEN2820"
|
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></A
|
|
><H3
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>2.2.5. I have a job which usually terminates with a non-zero status. When it
|
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does, I receive a mail with the exit status even if the command had no output.
|
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How can I avoid the mail?</H3
|
|
></P
|
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></DIV
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><DIV
|
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CLASS="ANSWER"
|
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><P
|
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><B
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> </B
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> You could disable mail entirely by setting the "mail" option to "no". But,
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if you still want to receive the standard output as mail, you can add an command
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which always evaluates to 0, like "/bin/true", after your primary command. This
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will not affect your job nor create additional output. For example:</P
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><TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>* * * * * /a/non/zero/status/job ; /bin/true</PRE
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></TD
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></TR
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></TABLE
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></DIV
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></DIV
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><DIV
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CLASS="QANDAENTRY"
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><DIV
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CLASS="QUESTION"
|
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><P
|
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><A
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|
NAME="AEN2826"
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></A
|
|
><H3
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>2.2.6. What does "loadavg" mean anyway?</H3
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></P
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></DIV
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><DIV
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CLASS="ANSWER"
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><P
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><B
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> </B
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> The "/proc/loadavg" file provides loadavg values. These values are (in
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order): the system load averages for the past 1, 5, and 15 minutes; a count of
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the (active tasks/active processes); the pid of last process run;
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</P
|
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><P
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|
> The active task count includes those processes marked as running or
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uninterruptable. A load average is an estimate of the average number of
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processes running within a specified period. The load averages are computed from
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active task count. They are updated each time active task counts are taken.
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</P
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><P
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>
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The load average formula is: <TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>loadavg(d,n) = active_task_cnt - (active_task_cnt - old_loadavg)*(1/exp(d/n)</PRE
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></TD
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></TR
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></TABLE
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>
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where: d is the time interval between active task count readings, typically every
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5 seconds; n is the time over which the readings are averaged.
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</P
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></DIV
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></DIV
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|
><DIV
|
|
CLASS="QANDAENTRY"
|
|
><DIV
|
|
CLASS="QUESTION"
|
|
><P
|
|
><A
|
|
NAME="AEN2834"
|
|
></A
|
|
><H3
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|
>2.2.7. How can I use fcrontab in scripts?</H3
|
|
></P
|
|
></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
|
><P
|
|
><B
|
|
> </B
|
|
> You can use pipes with "<B
|
|
CLASS="COMMAND"
|
|
>fcrontab -l</B
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>" (list the
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fcrontab) and "<B
|
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CLASS="COMMAND"
|
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>fcrontab -</B
|
|
>" (read the new fcrontab from
|
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input). For example: </P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><PRE
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|
CLASS="SCREEN"
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> <B
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CLASS="COMMAND"
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|
>echo -e "`fcrontab -l | grep -v exim`\n0 * * * * /usr/sbin/exim -q" | fcrontab -</B
|
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></PRE
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|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
> can be used to add a line. Another way to do it would be to:
|
|
list the fcrontab settings into a temporary file ("<B
|
|
CLASS="COMMAND"
|
|
>fcrontab -l >
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|
tmpfile</B
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|
>"); modify the temporary file ("<B
|
|
CLASS="COMMAND"
|
|
>echo $LINE >>
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|
tmpfile</B
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|
>"); replace the original fcrontab by the temporary; and
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|
finally, remove the temporary file ("<B
|
|
CLASS="COMMAND"
|
|
>fcrontab tmpfile ; rm -f
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|
tmpfile</B
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>").
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</P
|
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></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="QANDAENTRY"
|
|
><DIV
|
|
CLASS="QUESTION"
|
|
><P
|
|
><A
|
|
NAME="AEN2847"
|
|
></A
|
|
><H3
|
|
>2.2.8. Can I use fcron from time to time, for instance in a
|
|
script?</H3
|
|
></P
|
|
></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
|
><P
|
|
><B
|
|
> </B
|
|
>Let's suppose you use fcron in your ppp-up script. Fcron
|
|
can permit you to run some jobs at connection startup, but not at each
|
|
connection, like it would be if the job was run directly by the ppp-up script:
|
|
for instance, only once every week.</P
|
|
><P
|
|
><DIV
|
|
CLASS="EXAMPLE"
|
|
><A
|
|
NAME="AEN2852"
|
|
></A
|
|
><P
|
|
><B
|
|
>Example 2-5. Using fcron in a script: running a job once
|
|
every day, week, etc, at dialup connection</B
|
|
></P
|
|
><P
|
|
>You can use a script like:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># A ppp-up script ...
|
|
# run the jobs pending, then returns:
|
|
fcron -f -y -o</PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
>in conjunction with a fcrontab file like:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># a fcrontab file ...
|
|
%random(no),weekly,stdout * * /a/command/to/download/latest/mozilla/release
|
|
%monthly,stdout * * * /update/junkbuster/config/files</PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
></P
|
|
><P
|
|
>You can also use fcron to run some jobs until the end of
|
|
the connection. For instance, you can make fetchmail retrieve mails more often
|
|
during connection: we suppose that it is configured to retrieve mails every
|
|
hour, which launches a dialup connection if necessary, and we want it to check
|
|
for mails every 5 minutes while connected.</P
|
|
><P
|
|
><DIV
|
|
CLASS="EXAMPLE"
|
|
><A
|
|
NAME="AEN2860"
|
|
></A
|
|
><P
|
|
><B
|
|
>Example 2-6. Using fcron in a script: running a job until the
|
|
end of the connection</B
|
|
></P
|
|
><P
|
|
>ppp-up script:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># A ppp-up script ...
|
|
# run fcron at the beginning of the connection:
|
|
fcron -b</PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
>ppp-down script:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># A ppp-down script ...
|
|
# stop fcron at the end of the connection:
|
|
# -- Warning: killall may have unwanted effect on non linux systems --
|
|
killall -TERM fcron</PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
><P
|
|
>the fcrontab:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="100%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="PROGRAMLISTING"
|
|
># a fcrontab file ...
|
|
@volatile,first(0) 5 fetchmail</PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
></P
|
|
><P
|
|
>If you run fcron in several scripts, or if you run fcron
|
|
as a daemon and want also to run fcron in scripts, then you should use fcron,
|
|
fcrontab and fcrondyn's <CODE
|
|
CLASS="OPTION"
|
|
>--configfile</CODE
|
|
>.</P
|
|
><P
|
|
>For more details, see fcron's options
|
|
<CODE
|
|
CLASS="OPTION"
|
|
>--once</CODE
|
|
>, <CODE
|
|
CLASS="OPTION"
|
|
>--nosyslog</CODE
|
|
>,
|
|
<CODE
|
|
CLASS="OPTION"
|
|
>--firstsleep</CODE
|
|
> and <CODE
|
|
CLASS="OPTION"
|
|
>--configfile</CODE
|
|
> in <A
|
|
HREF="fcron.8.html"
|
|
><SPAN
|
|
CLASS="APPLICATION"
|
|
>fcron</SPAN
|
|
>(8)</A
|
|
>, and fcrontab's options <A
|
|
HREF="fcrontab.5.html#FCRONTAB.5.VOLATILE"
|
|
><CODE
|
|
CLASS="VARNAME"
|
|
>volatile</CODE
|
|
></A
|
|
>,
|
|
<A
|
|
HREF="fcrontab.5.html#FCRONTAB.5.STDOUT"
|
|
><CODE
|
|
CLASS="VARNAME"
|
|
>stdout</CODE
|
|
></A
|
|
>, <A
|
|
HREF="fcrontab.5.html#FCRONTAB.5.FIRST"
|
|
><CODE
|
|
CLASS="VARNAME"
|
|
>first</CODE
|
|
></A
|
|
> in <A
|
|
HREF="fcrontab.5.html"
|
|
><SPAN
|
|
CLASS="APPLICATION"
|
|
>fcrontab</SPAN
|
|
>(5)</A
|
|
></P
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="QANDAENTRY"
|
|
><DIV
|
|
CLASS="QUESTION"
|
|
><P
|
|
><A
|
|
NAME="AEN2886"
|
|
></A
|
|
><H3
|
|
>2.2.9. Can I run fcron without root's privileges?</H3
|
|
></P
|
|
></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
|
><P
|
|
><B
|
|
> </B
|
|
>Yes, you can. To do that, see the
|
|
following instructions, but please note that fcrondyn currently does *not* work
|
|
without root privileges.</P
|
|
><P
|
|
></P
|
|
><OL
|
|
TYPE="1"
|
|
><LI
|
|
><P
|
|
>First, create a directory where you'll install fcron,
|
|
and some subdirectories:</P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="90%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="SCREEN"
|
|
><SAMP
|
|
CLASS="PROMPT"
|
|
>bash$</SAMP
|
|
> <B
|
|
CLASS="COMMAND"
|
|
>mkdir /home/thib/fcron</B
|
|
>
|
|
<SAMP
|
|
CLASS="PROMPT"
|
|
>bash$</SAMP
|
|
> <B
|
|
CLASS="COMMAND"
|
|
>cd /home/thib/fcron</B
|
|
>
|
|
<SAMP
|
|
CLASS="PROMPT"
|
|
>bash$</SAMP
|
|
> <B
|
|
CLASS="COMMAND"
|
|
>mkdir doc man spool</B
|
|
></PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></LI
|
|
><LI
|
|
><P
|
|
>Then, run configure with option
|
|
<CODE
|
|
CLASS="OPTION"
|
|
>--with-run-non-privileged</CODE
|
|
>, set all user names and groups to yours,
|
|
and set appropriately the paths:</P
|
|
><P
|
|
><DIV
|
|
CLASS="WARNING"
|
|
><P
|
|
></P
|
|
><TABLE
|
|
CLASS="WARNING"
|
|
BORDER="1"
|
|
WIDTH="90%"
|
|
><TR
|
|
><TD
|
|
ALIGN="CENTER"
|
|
><B
|
|
>Warning</B
|
|
></TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
ALIGN="LEFT"
|
|
><P
|
|
>This option allows a non privileged user to run
|
|
fcron. When used, fcron does not change its rights before running a job
|
|
(i.e., if joe runs fcron, every job will run as joe). It means that
|
|
<EM
|
|
>YOU SHOULD NOT RUN FCRON AS A PRIVILEGED USER WHEN COMPILED
|
|
WITH THIS OPTION</EM
|
|
> or you'll have a serious security
|
|
hole.</P
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
></P
|
|
><TABLE
|
|
BORDER="0"
|
|
BGCOLOR="#E0E0E0"
|
|
WIDTH="90%"
|
|
><TR
|
|
><TD
|
|
><PRE
|
|
CLASS="SCREEN"
|
|
><SAMP
|
|
CLASS="PROMPT"
|
|
>bash$</SAMP
|
|
> <B
|
|
CLASS="COMMAND"
|
|
>./configure --with-run-non-privileged --with-rootname=thib
|
|
--with-rootgroup=thib --with-username=thib --with-groupname=thib
|
|
--with-etcdir=/home/thib/fcron --with-piddir=/home/thib/fcron
|
|
--with-fifodir=/home/thib/fcron --with-spooldir=/home/thib/fcron/spool
|
|
--with-docdir=/home/thib/fcron/doc --prefix=/home/thib/fcron</B
|
|
></PRE
|
|
></TD
|
|
></TR
|
|
></TABLE
|
|
></LI
|
|
></OL
|
|
><P
|
|
>The rest of the installation is described in the
|
|
<A
|
|
HREF="install.html"
|
|
>install file</A
|
|
>.</P
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="QANDAENTRY"
|
|
><DIV
|
|
CLASS="QUESTION"
|
|
><P
|
|
><A
|
|
NAME="AEN2913"
|
|
></A
|
|
><H3
|
|
>2.2.10. Has fcron some incompatibilities with Vixie cron?</H3
|
|
></P
|
|
></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
|
><P
|
|
><B
|
|
> </B
|
|
>As far as I know, fcron supports completely the syntax of
|
|
Vixie cron's crontab, excepted the @* syntax (@annually,
|
|
@weekly, etc: if you use that, you will have to replace it
|
|
with the explicit equivalent given in crontab(5)). So you
|
|
should not have much problem with that (otherwise, please
|
|
contact me at <CODE
|
|
CLASS="EMAIL"
|
|
><<A
|
|
HREF="mailto:fcron@free.fr"
|
|
>fcron@free.fr</A
|
|
>></CODE
|
|
>).</P
|
|
><P
|
|
>The main problem is about the management of the system (f)crontab.
|
|
Vixie cron monitors the changes on /etc/crontab every minute,
|
|
and automatically takes into account the changes if any.
|
|
As for now, fcron do not do that. Fcron do not support the
|
|
/etc/cron.d/ dir too, as it is just an extension of the /etc/crontab
|
|
file.
|
|
But be reassured: /etc/cron.{daily,weekly,monthly} are supported
|
|
by fcron (in fact, those dirs are not managed by fcron directly,
|
|
but by run-parts, which is independent from fcron).</P
|
|
><P
|
|
>So if you want to replace transparently Vixie cron by fcron,
|
|
all you have to do is creating a /usr/bin/crontab link to
|
|
/usr/bin/crontab, and to reinstall the system (f)crontab
|
|
with fcrontab /etc/crontab each time you modify it
|
|
(if you find something else to do, please tell me!).</P
|
|
><P
|
|
>You can also use the script script/check_system_crontabs
|
|
to generate a system fcrontab from /etc/(f)crontab and /etc/cron.d/,
|
|
and install it automatically. If you choose to do that, take
|
|
a look at the beginning of the script: you will find insctructions
|
|
on how to use it -- and a few warnings you should pay attention to.
|
|
With this script, the behavior of fcron should be very similar
|
|
to Vixie cron's one concerning /etc/crontab and /etc/cron.d/.
|
|
</P
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="QANDAENTRY"
|
|
><DIV
|
|
CLASS="QUESTION"
|
|
><P
|
|
><A
|
|
NAME="AEN2922"
|
|
></A
|
|
><H3
|
|
>2.2.11. How can I emulate an anacron entry?</H3
|
|
></P
|
|
></DIV
|
|
><DIV
|
|
CLASS="ANSWER"
|
|
><P
|
|
><B
|
|
> </B
|
|
>You should use a line similar to the following one:</P
|
|
><P
|
|
>@volatile,first(xx) BIG-period /your/command</P
|
|
><P
|
|
>where xx is the time you would have put in your anacron line.</P
|
|
></DIV
|
|
></DIV
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="NAVFOOTER"
|
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><HR
|
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ALIGN="LEFT"
|
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WIDTH="100%"><TABLE
|
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SUMMARY="Footer navigation table"
|
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
|
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><TD
|
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WIDTH="33%"
|
|
ALIGN="left"
|
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VALIGN="top"
|
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><A
|
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HREF="fcrondyn.1.html"
|
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ACCESSKEY="P"
|
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>Prev</A
|
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></TD
|
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="gpl.html"
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ACCESSKEY="N"
|
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>Next</A
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></TD
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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>fcrondyn</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="using-fcron.html"
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><TD
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VALIGN="top"
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>GNU GENERAL PUBLIC LICENSE</TD
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