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
[root@nagios ~]# ll /var/spool/cron/
total 8
-rw------- 1 root root 60 Apr 2 01:33 root
-rw------- 1 zwhset zwhset 68 Apr 2 01:51 zwhset
[root@nagios ~]# tail -5 /var/log/cron
Apr 2 17:24:01 nagios CROND[20544]: (root) CMD (/bin/sh ~/hello)
Apr 2 17:25:01 nagios CROND[20549]: (root) CMD (/bin/sh ~/hello)
Apr 2 17:25:01 nagios CROND[20550]: (root) CMD (/bin/sh ~/hello)
Apr 2 17:25:01 nagios CROND[20551]: (zwhset) CMD (echo "hello" >> ~/1.txt)
Apr 2 17:25:01 nagios CROND[20552]: (zwhset) CMD (echo "hello" >> ~/1.txt)
[root@nagios ~]# ps aux |grep cron
root 2074 0.0 0.5 117212 1316 ? Ss 01:40 0:04 crond
root 20641 0.0 0.6 139684 1468 pts/1 S+ 17:30 0:00 crontab -e
zwhset 20642 0.0 0.7 119284 1756 pts/1 S+ 17:30 0:00 /bin/vi /tmp/crontab.YphQpH
root 20663 0.0 0.3 103236 856 pts/0 S+ 17:31 0:00 grep cron
[root@nagios ~]# lsof -c crontab
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
crontab 20641 root cwd DIR 253,0 4096 130818 /root
crontab 20641 root rtd DIR 253,0 4096 2 /
crontab 20641 root txt REG 253,0 47520 401259 /usr/bin/crontab
crontab 20641 root mem REG 253,0 5952 261889 /lib64/security/pam_deny.so
crontab 20641 root mem REG 253,0 18592 261891 /lib64/security/pam_env.so
crontab 20641 root mem REG 253,0 18592 261903 /lib64/security/pam_limits.so
crontab 20641 root mem REG 253,0 10224 261901 /lib64/security/pam_keyinit.so
crontab 20641 root mem REG 253,0 10240 261906 /lib64/security/pam_loginuid.so
