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Top Forums Shell Programming and Scripting Scheduling a command to run every 3 days through cron Post 302344992 by jim mcnamara on Tuesday 18th of August 2009 07:07:41 AM
Old 08-18-2009
The problem with using DOW is that there are 7 days - plus sunday may not be day 0 depending on your locale. 7 does not divide evenly by 3.

If you literally want every third day try setting up a daily cron entry that checks for "thirdness"
Code:
$(date +%s)/86400

is the number of days since Jan 1 1970. # of days % 3 == 0 means it is a day divisible evenly by three.
This trick works for any weird number of days that don't track well as a DOW or a fixed day in the month.


Code:
[[ $(( ($(date +%s)/86400) % 3   )) -eq 0 ]] && /home/me/myscript.sh


Last edited by jim mcnamara; 08-18-2009 at 08:21 AM..
 

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lchage(1)						      General Commands Manual							 lchage(1)

NAME
lchage - Display or change user password policy SYNOPSIS
lchage [OPTION]... user DESCRIPTION
Displays or allows changing password policy of user. OPTIONS
-d, --date=days Set the date of last password change to days after Jan 1 1970. Set days to -1 to disable password expiration (i.e. to ignore --mindays, and --maxdays and related settings). Set days to 0 to enforce password change on next login. (This also disables password expiration until the password is changed.) -E, --expire=days Set the account expiration date to days after Jan 1 1970. Set days to -1 to disable account expiration. -i, --interactive Ask all questions when connecting to the user database, even if default answers are set up in libuser configuration. -I, --inactive=days Disable the account after days after password expires (after the user is required to change the password). Set days to -1 to keep the account enabled indefinitely after password expiration. -l, --list Only list current user's policy and make no changes. -m, --mindays=days Require at least days days between password changes. Set days to 0 or -1 to disable this requirement. If this value is larger than the value set by --maxdays, the user cannot change the pasword. -M, --maxdays=days Require changing the password after days since last password change. Set days to -1 to disable password expiration. -W, --warndays=days Start warning the user days before password expires (before the user is required to change the password). Set days to 0 or -1 to disable the warning. EXIT STATUS
The exit status is 0 on success, nonzero on error. NOTES
Note that "account expiration" (set by --expire) is distinct from "password expiration" (set by --maxdays). Account expiration happens on a fixed date regardless of password changes. Password expiration is relative to the date of last password change. libuser Nov 8 2012 lchage(1)
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