Analysis and solution of the reasons why crontab scheduled tasks are not executed

Preface

The following are the ways to implement Linux scheduled tasks: cron, anacron, at, etc. cron is the service name, crond is the background process, and crontab is a customized scheduled task table.

However, I learned a lot today. I have been using crontab for so long and I just realized that I need to start it.

Added a scheduled task but it doesn't work well

[root@dev-gl-lh1 ApiAgent]# cat /etc/crontab 
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
HOME=/

# For details see man 4 crontabs

# 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) OR sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * user-name command to be executed

# Cache coin mapping data */5 * * * * root /usr/bin/php /data/application/SwooleMoney/script/bin/cli.php CacheData cacheCoinMap

# Cache transaction pair information*/1 * * * * root /usr/bin/php /data/application/SwooleMoney/script/bin/cli.php CacheData cacheSymbol

# Delete depth data*/1 * * * * root /usr/bin/php /data/application/SwooleMoney/script/bin/cli.php CacheData clearExchangeDepths >/tmp/clearExchangeDepths.log
~          
~

The script is executed every minute, but the log is not displayed until the flowers are all gone.

# Check crontab status [root@dev-gl-lh1 ApiAgent]# /etc/init.d/crond status 
crond dead but pid file exists
# Start crontab service [root@dev-gl-lh1 ApiAgent]# /etc/init.d/crond start
Starting crond:

OK, the log output shows that the script was successfully executed, and I learned a lot.

Reference address: https://www.jb51.net/article/154290.htm

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