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

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

Summarize

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You may also be interested in:
  • Reasons why crontab scheduled tasks are not executed in Linux
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  • How to use crontab to execute a scheduled task once a second in Linux
  • How to use Linux Crontab to execute PHP scripts regularly
  • Detailed explanation of using crontab to execute tasks regularly under CentOS 7
  • How to execute tasks regularly under Linux and instructions on how to use crontab (collected and sorted)
  • Detailed explanation of using Crontab command to execute PHP files regularly in Ubuntu system
  • Detailed explanation of at and crontab commands for scheduled execution of tasks in Linux
  • Detailed explanation of crontab scheduled execution command under Linux
  • Solution to Linux crontab timing execution of Shell scripts when specific commands need to be executed

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