Hi All,
I want to run a cron job to run on the first saturday of each month at 1:30am. Would the following entry suffice this condition
30 1 6 * 6 wall %Will this work%
Appreciate your time.
Might depend on your environment (OS). Here is the man page for crontab in Linux:
www# man crontab
CRONTAB(1) CRONTAB(1)
NAME
crontab - manipulate per-user crontabs (Dillon's Cron)
SYNOPSIS
crontab file [-u user] - replace crontab from file
crontab - [-u user] - replace crontab from stdin
crontab -l [user] - list crontab for user
crontab -e [user] - edit crontab for user
crontab -d [user] - delete crontab for user
crontab -c dir - specify crontab directory
DESCRIPTION
crontab manipulates the crontab for a particular user. Only the superuser may specify
a different user and/or crontab directory. Generally the -e option is used to edit
your crontab. crontab will use /usr/bin/vi or the editor specified by your VISUAL
environment variable to edit the crontab.
Unlike other crond/crontabs, this crontab does not try to do everything under the sun.
Frankly, a shell script is much more able to manipulate the environment then cron and
I see no particular reason to use the user's shell (from his password entry) to run
cron commands when this requires special casing of non-user crontabs, such as those
for UUCP. When a crontab command is run, this crontab runs it with /bin/sh and sets
up only three environment variables: USER, HOME, and SHELL.
crond automatically detects changes in the time. Reverse-indexed time changes less
then an hour old will NOT re-run crontab commands already issued in the recovered
period. Forward-indexed changes less then an hour into the future will issue missed
commands exactly once. Changes greater then an hour into the past or future cause
crond to resynchronize and not issue missed commands. No attempt will be made to
issue commands lost due to a reboot, and commands are not reissued if the previously
issued command is still running. For example, if you have a crontab command 'sleep
70' that you wish to run once a minute, cron will only be able to issue the command
once every two minutes. If you do not like this feature, you can run your commands in
the background with an '&'.
The crontab format is roughly similar to that used by vixiecron, but without complex
features. Individual fields may contain a time, a time range, a time range with a
skip factor, a symbolic range for the day of week and month in year, and additional
subranges delimited with commas. Blank lines in the crontab or lines that begin with
a hash (#) are ignored. If you specify both a day in the month and a day of week, the
result is effectively ORd... the crontab entry will be run on the specified day of
week and on the specified day in the month.
# MIN HOUR DAY MONTH DAYOFWEEK COMMAND
# at 6:10 a.m. every day
10 6 * * * date
# every two hours at the top of the hour
0 */2 * * * date
# every two hours from 11p.m. to 7a.m., and at 8a.m.
0 23-7/2,8 * * * date
# at 11:00 a.m. on the 4th and on every mon, tue, wed
0 11 4 * mon-wed date
# 4:00 a.m. on january 1st
0 4 1 jan * date
# once an hour, all output appended to log file
0 4 1 jan * date >>/var/log/messages 2>&1
The command portion of the line is run with /bin/sh -c <command> and may therefore
contain any valid bourne shell command. A common practice is to run your command with
exec to keep the process table uncluttered. It is also common to redirect output to a
log file. If you do not, and the command generates output on stdout or stderr, the
result will be mailed to the user in question. If you use this mechanism for special
users, such as UUCP, you may want to create an alias for the user to direct the mail
to someone else, such as root or postmaster.
Internally, this cron uses a quick indexing system to reduce CPU overhead when looking
for commands to execute. Several hundred crontabs with several thousand entries can
be handled without using noticable CPU resources.
BUGS
Ought to be able to have several crontab files for any given user, as an organiza-
tional tool.
AUTHOR
Matthew Dillon (dillon@apollo.west.oic.com)
Maybe try:
# MIN HOUR DAY MONTH DAYOFWEEK COMMAND
# at 1:30 a.m. between the 1st and 7th day of the month on Sat.
30 1 1-7 * sat your_command