Linux package management and scheduled tasks, Linux package management tasks

Linux package management and scheduled tasks, Linux package management tasks
Chapter 4 software query 1st check whether the software is installed

Rpm-qa | grep cron to check whether the software is installed.

[Root @ znix ~] # Rpm-qa | grep cron

Crontabs-1.10-33.el6.noarch

Cronie-1.4.4-16.el6_8.2.x86_64

Cronie-anacron-1.4.4-16.el6_8.2.x86_64

[Root @ znix ~] #

1.2 check whether the query is running

[Root @ znix ~] # Ps-ef | grep crond

Root 1570 1 0 Sep02? 00:00:00 crond

Root 14941 14780 0 00:00:00 pts/0 grep -- color = auto crond

1.3 How to install crond 1.3.1 where does crond belong?

Crond, which cannot be installed separately, is a feature included in the software package.

Yum needs to be installed during installation,

[Root @ znix ~] # Yum install crond

Loaded plugins: fastestmirror, security

Setting up Install Process

Loading mirror speeds from cached hostfile

* Base: mirrors.btte.net

* Extras: mirrors.btte.net

* Updates: mirrors.sohu.com

Base | 3.7 kB

Extras | 3.4 kB: 00

Updates | 3.4 kB: 00

No package crond available.

Error: Nothing to do

1.3.2 query the Software Package

[Root @ znix ~] # Rpm-qf 'which crond'

Cronie-1.4.4-16.el6_8.2.x86_64

1.3.3 how to view the content in the Software Package

Rpm-ql displays the information in the software package. The names must be consistent.

[Root @ znix ~] # Rpm-ql cronie

/Etc/cron. d

/Etc/cron. d/0 hourly

/Etc/cron. deny

/Etc/pam. d/crond

/Etc/rc. d/init. d/crond

/Etc/sysconfig/crond

/Usr/bin/crontab

/Usr/sbin/crond

/Usr/share/doc/cronie-1.4.4

/Usr/share/doc/cronie-1.4.4/AUTHORS

/Usr/share/doc/cronie-1.4.4/COPYING

/Usr/share/doc/cronie-1.4.4/ChangeLog

/Usr/share/doc/cronie-1.4.4/INSTALL

/Usr/share/doc/cronie-1.4.4/README

/Usr/share/man/man1/crontab.1.gz

/Usr/share/man/man5/crontab.5.gz

/Usr/share/man/man8/cron.8.gz

/Usr/share/man/man8/crond.8.gz

/Var/spool/cron

1.3.4 how to view an installed software

How does rpm query the content of a software package?

Yum cannot be installed. It may be part of the software package.

Check which software package crond belongs and use the absolute path when querying

1.4 query the software package of ifconfig

[Root @ znix ~] #

[Root @ znix ~] # Rpm-qf 'which ifconfig'

Net-tools-1.60-114.el6.x86_64

[Root @ znix ~] # Rpm-ql net-tools

/Bin/dnsdomainname

/Bin/domainname

Chapter 2 scheduled tasks 2nd what is a scheduled task

Execute commands or scripts at the same time ).

2.2 scheduled tasks in the system

[Root @ znix ~] # Ls-ld/etc/cron *

Drwxr-xr-x. 2 root 4096 Aug 10/etc/cron. d

Drwxr-xr-x. 2 root 4096 Aug 10/etc/cron. daily

-Rw -------. 1 root 0 Aug 24 2016/etc/cron. deny

Drwxr-xr-x. 2 root 4096 Aug 10/etc/cron. hourly

Drwxr-xr-x. 2 root 4096 Aug 10/etc/cron. monthly

-Rw-r --. 1 root 457 Sep 27 2011/etc/crontab

Drwxr-xr-x. 2 root 4096 Sep 27 2011/etc/cron. weekly

/Etc/cron. deny prohibit users from using scheduled tasks and put the user name in it

2.2.1 log cutting-log polling

Separate logs at intervals

[Root @ znix ~] # Ls/var/log/messages *

/Var/log/messages-20170828

/Var/log/messages-20170814/var/log/messages-20170904

/Var/log/messages-20170821

2.2.2 scheduled tasks for log polling

[Root @ znix cron. daily] # cat/etc/logrotate. d/syslog

/Var/log/cron

/Var/log/maillog

/Var/log/messages

/Var/log/secure

/Var/log/spooler

{

Sharedscripts

Postrotate

/Bin/kill-HUP 'cat/var/run/syslogd. pid 2>/dev/null' 2>/dev/null | true

Endscript

}

2.3 use crontab 2.3.1

-E Edit

-L view

-U: Set scheduled tasks for the specified user.

[Root @ znix cron. daily] # crontab -- help

Crontab: invalid option --'-'

Crontab: usage error: unrecognized option

Usage: crontab [-u user] file

Crontab [-u user] [-e |-l |-r]

(Default operation is replace, per 1003.2)

(Edit user's crontab)

(List user's crontab)

-R (delete user's crontab)

-I (prompt before deleting user's crontab)

-S (selinux context)

2.3.2 specify a user's scheduled task

-U indicates the user

[Root @ znix ~] # Crontab-u oldboy-l

# Oldboy

[Root @ znix ~] # Ll/var/spool/cron/

Total 8

-Rw ------- 1 root 8 Sep 7 :23 oldboy

-Rw ------- 1 root 77 Sep 4 20:43 root

2.4 use of scheduled tasks-2.4.1 check whether the software of the scheduled task can be used

[Root @ znix ~] # Ps-ef | grep cron

Root 1570 1 0 Sep02? 00:00:00 crond

[Root @ znix ~] # Service crond status

Crond (pid 1570) is running...

[Root @ znix ~] #/Etc/init. d/crond status

Crond (pid 1570) is running...

2.4.2 check whether the scheduled task is automatically started upon startup

[Root @ znix ~] # Chkconfig | grep cron

Crond 0: off 1: off 2: on 3: on 4: on 5: on 6: off

2.4.3 linux daemon (service)

[Root @ znix ~] # Chkconfig | egrep "crond | network | rsyslog | sshd | sysstat"

Crond 0: off 1: off 2: on 3: on 4: on 5: on 6: off scheduled task

Network 0: off 1: off 2: on 3: on 4: on 5: on 6: off network SERVICE

Rsyslog 0: off 1: off 2: on 3: on 4: on 5: on 6: off System Log

Sshd 0: off 1: off 2: on 3: on 4: on 5: on 6: off remote connection Server

Sysstat 0: off 1: on 2: on 3: on 4: on 5: on 6: off monitoring system performance and efficiency

2.5 timing task-related files 2.5.1 timing task logs

[Root @ znix ~] # Tail-2/var/log/cron

Sep 7 10:23:42 znix crontab [15409]: (root) LIST (oldboy)

Sep 7 10:25:01 znix CROND [15412]: (root) CMD (/usr/sbin/ntpdate ntp1.aliyun.com>/dev/null 2> & 1)

2.5.2 directory of the scheduled task

[Root @ znix ~] # Ls/var/spool/cron

2.5.3 prohibit users from using scheduled tasks

[Root @ znix ~] # Cat/etc/cron. deny

2.6 command logs viewed in linux

When viewing large files, try not to cat them. Use other commands to quickly find the desired content.

Grep/egrep

Less

Tail/tail-f

Head

2.7 basic format of scheduled tasks

* *** CMD

CMD

* Indicates that

/N Interval

2.7.1 time in a scheduled task

[Root @ znix ~] # 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

2.7.2 scheduled task-Synchronize the system time every five minutes

1. What command is used? First, test the command. If there is no error, write it to the scheduled task.

[Root @ znix ~] # Ntpdate ntp1.aliyun.com

7 Sep 10:52:57 ntpdate [15460]: adjust time server 182.92.12.11 offset 0.479762 sec

2. Write a scheduled task-use an absolute path to write a scheduled task. Add 2> & 1 to the end to indicate that the task is correct. All errors are output to the same file.

[Root @ znix ~] # Crontab-e

### Time tongbu

*/5 */usr/sbin/ntpdate ntp1.aliyun.com>/dev/null 2> & 1

3. Check the result. You can view the log or the command execution result.

[Root @ znix ~] # Tail-1/var/log/cron

Sep 7 10:55:01 znix CROND [15466]: (root) CMD (/usr/sbin/ntpdate ntp1.aliyun.com>/dev/null 2> & 1)

Instance 2-1 append its name to/oldboy/oldboy.txt every minute

* ***/Bin/echo clsn>/oldboy/oldboy.txt

Run the tail command to view the command execution status. The file content is displayed.

[Root @ znix ~] # Tail-f/oldboy/oldboy.txt

Clsn

Clsn

Clsn

View the log and view the command execution time.

[Root @ znix ~] # Tail-3/var/log/cron

Sep 7 12:05:01 znix CROND [15674]: (root) CMD (/bin/echo clsn>/oldboy/oldboy.txt 2> & 1)

Sep 7 12:06:01 znix CROND [15678]: (root) CMD (/bin/echo clsn>/oldboy/oldboy.txt 2> & 1)

Sep 7 12:07:01 znix CROND [15681]: (root) CMD (/bin/echo clsn>/oldboy/oldboy.txt 2> & 1)

2.8 note

Error:

* ***/Bin/echo "oldboy">/oldboy/oldboy.txt>/dev/null 2> & 1

Instance 2-2 cannot be used at the same time.

Commands/scripts in scheduled tasks are directed to null

/Dev/null 2> & 1

Commands/scripts in scheduled tasks are appended to files.

/Oldboy/oldboy.txt 2> & 1