Crontab routine work arrangement for Linux

Routine work arrangement for crontab in Linux

1. What is crontab?

Periodically process the daemons for to-do items, and the class dead task schedule.

2.crontab command resolution.

Example:

0 0 * * 1-5 cd/home/hiperry;/shutdwon.sh >/logs/shutdwon.log 2>&1

--Executes a custom shutdown script at 12 o'clock every night and writes log information to the specified log file.

Command resolution:

#----------------minutes (0-59)

# |-------------hours (0-23)

The day of the month of the----------(1-31)

# | | | |-------month (1-12) OR jan,feb,mar,apr ...

# | | | | |-----WEEK (0-6) (sunday=0 or 7) or Sun,mon,tue,wed,thu,fri,sat

# | | | | |

* * * * * * * The command to be executed

> represents where to redirect, for example: echo "123" >/home/123.txt

1 indicates stdout standard output, the system default is 1, so ">/dev/null" is equivalent to "1>/dev/null"

2 indicates stderr standard error

& means equal to, 2>&1, indicating 2 output redirection equals 1

2>&1 indicates that all standard output and error output will be redirected to a file called Out.file

3.crontab Common operation

Listing crontab files: crontab-l

Edit crontab File: crontab-e

Delete crontab file: crontab-r