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Diffstat (limited to 'mcron.texinfo')
| -rw-r--r-- | mcron.texinfo | 87 |
1 files changed, 51 insertions, 36 deletions
diff --git a/mcron.texinfo b/mcron.texinfo index 63f4415..6f7ca24 100644 --- a/mcron.texinfo +++ b/mcron.texinfo @@ -10,12 +10,6 @@ This file documents the @code{mcron} command for running jobs at scheduled times. -IMPORTANT NOTICE: -IT IS VERY LIKELY THAT THE CRON AND CRONTAB PROGRAMS DESCRIBED IN THIS -MANUAL HAVE NOT BEEN INSTALLED IN YOUR SYSTEM (THEY ARE CURRENTLY -BROKEN). THUS, ONLY THE MCRON PERSONALITY IS CURRENTLY AVAILABLE FOR -USE. - Copyright (C) 2003 Dale Mellor This is free software. See the source files for the terms of the copyright. @@ -254,7 +248,7 @@ then run the command @code{mcron}. Alternatively (full compatibility with Vixie cron), set your environment variable @code{EDITOR} to your favorite editor, run @code{crontab -e}, put the above line into the edit buffer, save and -exit. For this to work the @code{crond} daemon must be already running +exit. For this to work the @code{cron} daemon must be already running on your system, by root. @node Syntax, Invoking, Simple examples, Top @@ -272,8 +266,9 @@ on your system, by root. @findex job In Guile-formatted configuration files each command that needs executing is introduced with the @code{job} function. This function -always takes exactly two arguments, the first a time specification, -and the second a command specification. +always takes two arguments, the first a time specification, and the +second a command specification. An optional third argument may contain +a string to display when this job is listed in a schedule. @cindex time specification, procedure @cindex procedure time specification @@ -521,23 +516,19 @@ there is a bug in the program. This section is also copied verbatim from Paul Vixie's documentation for his cron program, and his copyright notice is duly reproduced below. -@cindex /etc/crontab -@cindex system crontab -@cindex incompatibility -@cindex vixie incompatibility -There is one single exception to the above. @strong{Mcron does not -notice changes made to /etc/crontab}. If a change is made, then it is -necessary to kill the cron daemon and restart it for the change to -take effect. - There are three problems with this specification. @cindex zero'th day of month @cindex 0'th day of month 1. It is allowed to specify days of the month in the range 0-31. What -does it mean to specify day 0? Well, if I'm not mistaken mcron will -run the command on the last day of the previous month (but don't rely -on this). I don't know what Vixie cron would have done. +does it mean to specify day 0? Looking at the Vixie source code, it +seems that if this date appears as part of a list, it has no +effect. However, if it appears on its own, the effect is to say +``don't run on any particular day of the month, only take the week-day +specification into account.'' Mcron has been coded to mimic this +behaviour as a special case (unmodified mcron logic implies that this +date specification would cause jobs to run on the last day of the +previous month). @cindex thirteenth month of year @cindex 13th month of year @@ -901,21 +892,19 @@ standard output. @cindex running crond @cindex /var/cron/tabs @cindex /var/run/cron.pid -If the program runs by the name of cron or crond, then it will read -all the files in /var/cron/tabs (which should only be readable by -root) and the file /etc/crontab, and then detaches itself from the -terminal to live forever as a daemon process. Additionally, it puts -its PID into /var/run/cron.pid, and listens for SIGHUPs, in which case -it will look for a file /var/cron/update which should contain a single -username, and the program will re-read that user's crontab. This is -for correct functioning with the crontab program. - -@cindex /etc/crontab -@cindex incompatibility -@strong{NOTE} that it does not detect changes in /etc/crontab; if this file -is ever changed then it will be necessary to kill and then restart the -daemon. This is the one and only incompatibility with Vixie's cron -program. +If the program runs by the name of @code{cron} or @code{crond}, then +it will read all the files in @code{/var/cron/tabs} (which should only +be readable by root) and the file @code{/etc/crontab}, and then +detaches itself from the terminal to live forever as a daemon +process. Additionally, it creates a UNIX socket at +@code{/var/cron/socket}, and listens for messages sent to that socket +consisting of a user name whose crontabs have been changed. In this +case, the program will re-read that user's crontab. This is for +correct functioning with the crontab program. + +Further, if the @code{--noetc} option was not used, a job is scheduled +to run every minute to check if /etc/crontab has been modified +recently. If so, this file will also be re-read. The options which may be used with this program are as follows. @@ -939,6 +928,32 @@ information about the version and copyright for the current program. This causes a short but complete usage message to be displayed on standard output. +@item -s [count] +@itemx --schedule[=count] +@cindex printout of jobs schedule +@cindex schedule of jobs, listing +@cindex options, schedule +@cindex options, -s +@cindex -s option +@cindex --schedule option +With this option specified no commands are run. Instead, the program +computes the times the commands would be run and prints the +information to the screen, and then immediately exits. + +The count, if supplied, indicates the number of commands to +display. The default value is 8. + +@cindex -n option +@cindex --noetc option +@cindex options, -n +@cindex options, --noetc +@item -n +@itemx --noetc +This tells cron not to add a job to the system which wakes up every +minute to check for modifications to @code{/etc/crontab}. It is +recommended that this option be used (and further that the +@code{/etc/crontab} file be taken off the system altogether!) + @end table @node Running crontab, Exit codes, Running cron or crond, Invoking |