为什么我的crontab无法正常工作，如何解决它？

#1 楼

 # Example of job definition:
 # .---------------- minute (0 - 59)
 # |  .------------- hour (0 - 23)
 # |  |  .---------- day of month (1 - 31)
 # |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
 # |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7)
 # |  |  |  |  |
 # *  *  *  *  *   command to be executed

 # Example of job definition:
 # .---------------- minute (0 - 59)
 # |  .------------- hour (0 - 23)
 # |  |  .---------- day of month (1 - 31)
 # |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
 # |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7)
 # |  |  |  |  |
 # *  *  *  *  * user-name  command to be executed

MAILTO=user@somehost.tld
1 2 * * * /path/to/your/command

1 2 * * * /path/to/your/command &>/tmp/mycommand.log
1 2 * * * /path/to/your/command >/tmp/mycommand.log 2>&1

grep CRON /var/log/syslog 

ps -ef | grep cron | grep -v grep

root    1224   1  0 Nov16 ?    00:00:03 cron

root    2018   1  0 Nov14 ?    00:00:06 crond

/sbin/service cron start

/sbin/service crond start

 1 2 * * * /path/to/your/command

 PATH=/bin:/usr/bin:/path/to/something/else
 1 2 * * * command 

# cron entry
* * * * * cat >$HOME/cron.out%foo%bar%baz

foo
bar
baz

* * * * * /path/to/command --day "$(date "+\%Y\%m\%d")"

crontab -e

#2 楼

#3 楼

#4 楼

*/5 * * * * /path/to/your/command

*/7 * * * * /path/to/your/command

# The following lines create a batch that runs every 40 minutes i.e.

# runs on   0:00, 0:40,        02:00, 02:40         04:00 etc to 22:40
0,40 */2 * * * /path/to/your/command

# runs on               01:20,               03:20,       etc to 23:20
20 1/2 * * * /path/to/your/command

# Combined: 0:00, 0:40, 01:20, 02:00, 02:40, 03:20, 04:00 etc.

* * * * * /usr/bin/flock -n /tmp/fcj.lockfile /usr/local/bin/frequent_cron_job 

#!/bin/bash
# seven-minute-job
# This batch will only run when 420 seconds (7 min) have passed
# since the file /tmp/lastrun was either created or updated

if [ ! -f /tmp/lastrun ] ; then
    touch /tmp/lastrun
fi

if [ $(( $(date +%s) - $(date -r /tmp/lastrun +%s) )) -lt 420 ] ; then
     # The minimum interval of 7 minutes between successive batches hasn't passed yet.
    exit 0
fi

####  Start running your actual batch job below
  
/path/to/your/command

#### actual batch job is done, now update the time stamp
date > /tmp/lastrun
#EOF

* * * * * /path/to/your/seven-minute-job

#!/bin/bash
# first-monday-of-the-month-housekeeping-job

# exit if today is not a Monday (and prevent locale issues by using the day number) 
if [ $(date +%u) != 1 ] ; then
  exit 0
fi

# exit if today is not the first Monday
if [ $(date +%d) -gt 7 ] ; then
  exit 0
fi

####  Start running your actual batch job below
  
/path/to/your/command

#EOF

#5 楼

#6 楼

$ ./certbot ... 

*/10 * * * * ./certbot ....

 0 22 * * * /path/to/certbot .....
 

$ nano ~/envtst.sh

 #!/bin/sh 
/bin/echo "env report follows for user "$USER >> /home/you/envtst.sh.out 
/usr/bin/env >> /home/you/envtst.sh.out 
/bin/echo "env report for user "$USER" concluded" >> /home/you/envtst.sh.out
/bin/echo " " >> /home/you/envtst.sh.out
 

 $ chmod a+rx ~/envtst.sh
 

 $ ./envtst.sh $$ cat /home/you/envtst.sh.out
 

 $ crontab -e -u root
 

 * * * * *  /home/you/envtst.sh >> /home/you/envtst.sh.err 2>&1