Originally published at: Disable cron emails (solution)
This article lists three common methods to disable cron emails and another solution to send emails only when errors occur. Cron is a daemon that executes scheduled commands. More specifically, the software utility cron is a time-based job scheduler for Unix-like operating systems like Linux. You can use cron to set up jobs to run…
couldn’t you use cron -L and follow the instructions in crontab (1 & 5) man pages?
And Debian uses it’s own version , See cron (8) man page “Debian Specific” section:
DEBIAN SPECIFIC
Debian introduces some changes to cron that were not originally avail-
able upstream. The most significant changes introduced are:
— Support for /etc/cron.{hourly,daily,weekly,monthly} via
/etc/crontab,
— Support for /etc/cron.d (drop-in dir for package crontabs),
— PAM support,
— SELinux support,
— auditlog support,
— DST and other time-related changes/fixes,
— SGID crontab(1) instead of SUID root,
— Debian-specific file locations and commands,
— Debian-specific configuration (/etc/default/cron),
— numerous other smaller features and fixes.
Support for /etc/cron.hourly, /etc/cron.daily, /etc/cron.weekly and
/etc/cron.monthly is provided in Debian through the default setting of
the /etc/crontab file (see the system-wide example in crontab(5)). The
default system-wide crontab contains four tasks: run every hour, every
day, every week and every month. Each of these tasks will execute run-
parts providing each one of the directories as an argument. These
tasks are disabled if anacron is installed (except for the hourly task)
to prevent conflicts between both daemons.
As described above, the files under these directories have to pass some
sanity checks including the following: be executable, be owned by root,
not be writable by group or other and, if symlinks, point to files
owned by root. Additionally, the file names must conform to the file-
name requirements of run-parts: they must be entirely made up of let-
ters, digits and can only contain the special signs underscores ('_')
and hyphens ('-'). Any file that does not conform to these require-
ments will not be executed by run-parts. For example, any file con-
taining dots will be ignored. This is done to prevent cron from run-
ning any of the files that are left by the Debian package management
system when handling files in /etc/cron.d/ as configuration files (i.e.
files ending in .dpkg-dist, .dpkg-orig, .dpkg-old, and .dpkg-new).
This feature can be used by system administrators and packages to in-
clude tasks that will be run at defined intervals. Files created by
packages in these directories should be named after the package that
supplies them.
Support for /etc/cron.d is included in the cron daemon itself, which
handles this location as the system-wide crontab spool. This directory
can contain any file defining tasks following the format used in
/etc/crontab, i.e. unlike the user cron spool, these files must provide
the username to run the task as in the task definition.
Files in this directory have to be owned by root, do not need to be ex-
ecutable (they are configuration files, just like /etc/crontab) and
must conform to the same naming convention as used by run-parts(8) :
they must consist solely of upper- and lower-case letters, digits, un-
derscores, and hyphens. This means that they cannot contain any dots.
If the -l option is specified to cron (this option can be setup through
/etc/default/cron, see below), then they must conform to the LSB name-
space specification, exactly as in the --lsbsysinit option in run-
parts.
The intended purpose of this feature is to allow packages that require
finer control of their scheduling than the
/etc/cron.{hourly,daily,weekly,monthly} directories to add a crontab
file to /etc/cron.d. Such files should be named after the package that
supplies them.
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