7.17 10.23-10.27

Posted 2020-12-05

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10.23 linux任务计划cron

linux任务计划配置文件

[[email protected] ~]# cat /etc/crontab

SHELL=/bin/bash 文件中定义的shell

PATH=/sbin:/bin:/usr/sbin:/usr/bin 定义的环境变量（命令的路径）

MAILTO=root 给哪个用户发送邮件

# For details see man 4 crontabs

以下是任务计划的格式

# Example of job definition:

# .---------------- minute (0 - 59) 时间的分钟

# | .------------- hour (0 - 23) 时间的小时

# | | .---------- day of month (1 - 31) 一个月中的日期

# | | | .------- month (1 - 12) OR jan,feb,mar,apr ... 某个月（可以写数字或英文简写）

# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat 星期几（0或7均表示周日）

# | | | | |

# * * * * * user-name command to be executed 用户要执行的命令

定义一个任务计划

[[email protected] ~]# crontab –e 用法同vim

no crontab for root - using an empty one

0 3 * * * /bin/bash /usr/local/sbin/123.sh>>/tmp/123.log 2>>/tmp/123.log

解释：在每月每周每日的3点执行shell脚本123.sh，将执行结果中正确的内容追加重定向到123.log文件，将执行结果中错误的内容也追加重定向到123.log文件

[[email protected] ~]# crontab –e

no crontab for root - using an empty one

0 3 1-10 */2 2,5 /bin/bash /usr/local/sbin/123.sh>>/tmp/123.log 2>>/tmp/123.log

解释：在偶数月的1到10号的周二和周五的凌晨3点执行shell脚本

如何指定年份执行脚本？

每年的同一个日期的星期一定是不一样的，可以基于此确定脚本执行的年份

启动任务计划cron

[[email protected] ~]# ps aux|grep cron

root 503 0.0 0.1 126264 1696 ? Ss 03:48 0:00 /usr/sbin/crond -n

root 6833 0.0 0.0 112676 984 pts/0 S+ 20:45 0:00 grep --color=auto cron

有上面的进程则说明服务已经启动

[[email protected] ~]# systemctl status crond

● crond.service - Command Scheduler

Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)

Active: active (running) since 日 2018-07-15 22:05:31 CST; 1 day 22h ago

Main PID: 503 (crond)

CGroup: /system.slice/crond.service

└─503 /usr/sbin/crond -n

7月 15 22:05:31 hyc-01-01 systemd[1]: Started Command Scheduler.

7月 15 22:05:31 hyc-01-01 systemd[1]: Starting Command Scheduler...

7月 15 22:05:31 hyc-01-01 crond[503]: (CRON) INFO (RANDOM_DELAY will be scaled....)

7月 15 22:05:32 hyc-01-01 crond[503]: (CRON) INFO (running with inotify support)

Hint: Some lines were ellipsized, use -l to show in full.

以上active为active（running）且为绿色说明服务正常启动

[[email protected] ~]# systemctl stop crond

[[email protected] ~]# systemctl status crond

● crond.service - Command Scheduler

Loaded: loaded (/usr/lib/systemd/system/crond.service; enabled; vendor preset: enabled)

Active: inactive (dead) since 二 2018-07-17 20:50:11 CST; 2s ago

Main PID: 503 (code=exited, status=0/SUCCESS)

7月 15 22:05:31 hyc-01-01 systemd[1]: Started Command Scheduler.

7月 15 22:05:31 hyc-01-01 systemd[1]: Starting Command Scheduler...

7月 15 22:05:31 hyc-01-01 crond[503]: (CRON) INFO (RANDOM_DELAY will be scaled....)

7月 15 22:05:32 hyc-01-01 crond[503]: (CRON) INFO (running with inotify support)

7月 17 20:50:11 hyc-01-01 systemd[1]: Stopping Command Scheduler...

7月 17 20:50:11 hyc-01-01 systemd[1]: Stopped Command Scheduler.

Hint: Some lines were ellipsized, use -l to show in full.

此时crond服务未启动

crond任务计划中的脚本未执行的原因

有时脚本中用到的命令不在crond配置文件（/etc/crontab）定义的PATH路径中，导致找不到命令无法执行：

解决办法：

1 在配置文件的PATH路径中加入对应命令的路径

2 写任务计划时直接写命令的绝对路径

建议写任务计划时将执行的正确和错误结果重定向到文件，这样使执行过程有据可查，可以清楚的知道任务是否正确执行

-l 查看系统当前用户的任务计划

[[email protected] ~]# crontab -l

0 3 * * * /bin/bash /usr/local/sbin/123.sh>>/tmp/123.log 2>>/tmp/123.log

crontab文件

[[email protected] ~]# cat /var/spool/cron/root

0 3 * * * /bin/bash /usr/local/sbin/123.sh>>/tmp/123.log 2>>/tmp/123.log

该文件存放crontab –l命令显示的内容

10.24 chkconfig工具

chkconfig工具在centos6及更早的版本中常用，centos7不常用

查看当前系统中使用chkconfig工具的服务

[[email protected] ~]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:开 3:开 4:开 5:开 6:关

centos6及更早版本使用的服务管理机制叫SysV，centos7使用的服务管理机制为systemd；

centos7中的服务管理进程为systemd，centos6的服务管理进程为init；

[[email protected] ~]# ls /etc/init.d 以上两个服务脚本的存放位置

functions netconsole network README

关闭network服务

[[email protected] ~]# chkconfig network off

[[email protected] ~]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:关 3:关 4:关 5:关 6:关

以上0-6的开关表示在0-6的7个级别分别是什么状态，数字对应的开关表示开机启动或关闭

几个级别的状态：

0 关机状态

1 单用户模式

2 比3级别少了NFS服务

3 无图形化界面的多用户模式

4 保留级别

5 多用户带图形

6 重启

centos6及更早的版本通过修改/etc/inittab定义服务的运行级别，centos7中已不再使用

指定某一级别时关闭或开启服务

[[email protected] ~]# chkconfig --level 3 network on

[[email protected] ~]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:关 3:开 4:关 5:关 6:关

[[email protected] ~]# chkconfig --level 234 network on

[[email protected] ~]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:开 3:开 4:开 5:关 6:关

一般0/1/6级别服务关闭，其他级别服务可以选择性开启

将某个服务/脚本加入chkconfig列表

[[email protected] init.d]# cp network 123 123作为新的脚本/服务

[[email protected] init.d]# ls

123 functions netconsole network README

[[email protected] init.d]# chkconfig --add 123 将123加入chkconfig服务列表

[[email protected] init.d]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

123 0:关 1:关 2:开 3:开 4:开 5:开 6:关

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:开 3:开 4:开 5:关 6:关

加入服务列表的要求：

1 将指定的脚本放到/etc/init.d目录下

2 文件名称无要求

3 文件内容为shell脚本

4 文件中必须有红字内容才能被识别

#! /bin/bash

# network Bring up/down networking

# chkconfig: 2345 10 90

# description: Activates/Deactivates all network interfaces configured to

# start at boot time.

### BEGIN INIT INFO

…

从列表中删除某服务

[[email protected] init.d]# chkconfig --del 123

[[email protected] init.d]# chkconfig --list

注：该输出结果只显示 SysV 服务，并不包含

原生 systemd 服务。SysV 配置数据

可能被原生 systemd 配置覆盖。

要列出 systemd 服务，请执行 'systemctl list-unit-files'。

查看在具体 target 启用的服务请执行

'systemctl list-dependencies [target]'。

netconsole 0:关 1:关 2:关 3:关 4:关 5:关 6:关

network 0:关 1:关 2:开 3:开 4:开 5:关 6:关

10.25 systemd管理服务

systemd是centos7的服务管理机制

列出systemd中的service

[[email protected] ~]# systemctl list-units --all --type=service

UNIT LOAD ACTIVE SUB DESCRIPTION

auditd.service loaded active running Security Auditing Service

brandbot.service loaded inactive dead Flexible Branding Service

chronyd.service loaded active running NTP client/server

cpupower.service loaded inactive dead Configure CPU power relate

crond.service loaded active running Command Scheduler

dbus.service loaded active running D-Bus System Message Bus

● display-manager.service not-found inactive dead display-manager.service

dracut-shutdown.service loaded inactive dead Restore /run/initramfs

ebtables.service loaded inactive dead Ethernet Bridge Filtering

emergency.service loaded inactive dead Emergency Shell

● exim.service not-found inactive dead exim.service

firewalld.service loaded active running firewalld - dynamic firewa

[email protected] loaded active running Getty on tty1

ip6tables.service loaded inactive dead IPv6 firewall with ip6tabl

● ipset.service not-found inactive dead ipset.service

iptables.service loaded inactive dead IPv4 firewall with iptable

irqbalance.service loaded inactive dead irqbalance daemon

● kdump.service loaded failed failed Crash recovery kernel armi

kmod-static-nodes.service loaded active exited Create list of required st

microcode.service loaded inactive dead Load CPU microcode update

network.service loaded active exited LSB: Bring up/down network

NetworkManager-wait-online.service loaded active exited Network Manager Wait

NetworkManager.service loaded active running Network Manager

● ntpd.service not-found inactive dead ntpd.service

● ntpdate.service not-found inactive dead ntpdate.service

plymouth-quit-wait.service loaded inactive dead Wait for Plymouth Boot Scr

plymouth-quit.service loaded inactive dead Terminate Plymouth Boot Sc

plymouth-read-write.service loaded inactive dead Tell Plymouth To Write Out

plymouth-start.service loaded inactive dead Show Plymouth Boot Screen

polkit.service loaded active running Authorization Manager

postfix.service loaded active running Postfix Mail Transport Age

rc-local.service loaded inactive dead /etc/rc.d/rc.local Compati

rescue.service loaded inactive dead Rescue Shell

rhel-autorelabel-mark.service loaded inactive dead Mark the need to relabel

rhel-autorelabel.service loaded inactive dead Relabel all filesystems, i

rhel-configure.service loaded inactive dead Reconfigure the system on

rhel-dmesg.service loaded active exited Dump dmesg to /var/log/dme

rhel-import-state.service loaded active exited Import network configurati

rhel-loadmodules.service loaded inactive dead Load legacy module configu

rhel-readonly.service loaded active exited Configure read-only root s

rsyslog.service loaded active running System Logging Service

[email protected] loaded inactive dead M

● sendmail.service not-found inactive dead sendmail.service

● sntp.service not-found inactive dead sntp.service

sshd-keygen.service loaded inactive dead OpenSSH Server Key Generat

sshd.service loaded active running OpenSSH server daemon

● syslog.service not-found inactive dead syslog.service

systemd-ask-password-console.service loaded inactive dead Dispatch Password

systemd-ask-password-plymouth.service loaded inactive dead Forward Password

systemd-ask-password-wall.service loaded inactive dead Forward Password Requ

systemd-binfmt.service loaded inactive dead Set Up Additional Binary F

systemd-firstboot.service loaded inactive dead First Boot Wizard

systemd-fsck-root.service loaded inactive dead File System Check on Root

systemd-hwdb-update.service loaded inactive dead Rebuild Hardware Database

systemd-initctl.service loaded inactive dead /dev/initctl Compatibility

systemd-journal-catalog-update.service loaded inactive dead Rebuild Journal

systemd-journal-flush.service loaded active exited Flush Journal to Persiste

systemd-journald.service loaded active running Journal Service

systemd-logind.service loaded active running Login Service

systemd-machine-id-commit.service loaded inactive dead Commit a transient ma

systemd-modules-load.service loaded inactive dead Load Kernel Modules

● systemd-random-seed-load.service not-found inactive dead systemd-random-seed-lo

systemd-random-seed.service loaded active exited Load/Save Random Seed

systemd-readahead-collect.service loaded inactive dead Collect Read-Ahead Da

systemd-readahead-done.service loaded inactive dead Stop Read-Ahead Data Col

systemd-readahead-replay.service loaded inactive dead Replay Read-Ahead Data

systemd-reboot.service loaded inactive dead Reboot

systemd-remount-fs.service loaded active exited Remount Root and Kernel Fi

systemd-shutdownd.service loaded inactive dead Delayed Shutdown Service

systemd-sysctl.service loaded active exited Apply Kernel Variables

● systemd-sysusers.service not-found inactive dead systemd-sysusers.service

● systemd-timesyncd.service not-found inactive dead systemd-timesyncd.service

systemd-tmpfiles-clean.service loaded inactive dead Cleanup of Temporary Dir

systemd-tmpfiles-setup-dev.service loaded active exited Create Static Device

systemd-tmpfiles-setup.service loaded active exited Create Volatile Files an

systemd-udev-trigger.service loaded active exited udev Coldplug all Devices

systemd-udevd.service loaded active running udev Kernel Device Manager

systemd-update-done.service loaded inactive dead Update is Completed

systemd-update-utmp-runlevel.service loaded inactive dead Update UTMP about

systemd-update-utmp.service loaded active exited Update UTMP about System B

systemd-user-sessions.service loaded active exited Permit User Sessions

systemd-vconsole-setup.service loaded active exited Setup Virtual Console

tuned.service loaded active running Dynamic System Tuning Daem

vgauthd.service loaded active running VGAuth Service for open-vm

vmtoolsd.service loaded active running Service for virtual machin

LOAD = Reflects whether the unit definition was properly loaded.

ACTIVE = The high-level unit activation state, i.e. generalization of SUB.

SUB = The low-level unit activation state, values depend on unit type.

85 loaded units listed.

To show all installed unit files use 'systemctl list-unit-files'.

lines 78-93/93 (END)

DESCRIPTION：描述信息

SUB:是否running

ACTIVE:是否active

LOAD：是否load

不加—all则不会列出inactive（未激活状态）的service

[[email protected] ~]# systemctl list-units --type=service

UNIT LOAD ACTIVE SUB DESCRIPTION

auditd.service loaded active running Security Auditing Service

chronyd.service loaded active running NTP client/server

crond.service loaded active running Command Scheduler

dbus.service loaded active running D-Bus System Message Bus

firewalld.service loaded active running firewalld - dynamic firewall d

[email protected] loaded active running Getty on tty1

● kdump.service loaded failed failed Crash recovery kernel arming

kmod-static-nodes.service loaded active exited Create list of required static

network.service loaded active exited LSB: Bring up/down networking

NetworkManager-wait-online.service loaded active exited Network Manager Wait Onli

NetworkManager.service loaded active running Network Manager

polkit.service loaded active running Authorization Manager

postfix.service loaded active running Postfix Mail Transport Agent

rhel-dmesg.service loaded active exited Dump dmesg to /var/log/dmesg

rhel-import-state.service loaded active exited Import network configuration f

rhel-readonly.service loaded active exited Configure read-only root suppo

rsyslog.service loaded active running System Logging Service

sshd.service loaded active running OpenSSH server daemon

systemd-journal-flush.service loaded active exited Flush Journal to Persistent St

systemd-journald.service loaded active running Journal Service

systemd-logind.service loaded active running Login Service

systemd-random-seed.service loaded active exited Load/Save Random Seed

systemd-remount-fs.service loaded active exited Remount Root and Kernel File S

systemd-sysctl.service loaded active exited Apply Kernel Variables

systemd-tmpfiles-setup-dev.service loaded active exited Create Static Device Node

systemd-tmpfiles-setup.service loaded active exited Create Volatile Files and Dir

systemd-udev-trigger.service loaded active exited udev Coldplug all Devices

systemd-udevd.service loaded active running udev Kernel Device Manager

systemd-update-utmp.service loaded active exited Update UTMP about System Boot/

systemd-user-sessions.service loaded active exited Permit User Sessions

systemd-vconsole-setup.service loaded active exited Setup Virtual Console

tuned.service loaded active running Dynamic System Tuning Daemon

vgauthd.service loaded active running VGAuth Service for open-vm-too

vmtoolsd.service loaded active running Service for virtual machines h

LOAD = Reflects whether the unit definition was properly loaded.

ACTIVE = The high-level unit activation state, i.e. generalization of SUB.

SUB = The low-level unit activation state, values depend on unit type.

34 loaded units listed. Pass --all to see loaded but inactive units, too.

To show all installed unit files use 'systemctl list-unit-files'.

lines 27-42/42 (END)

这里显示的内容包含了target、service、socket，不仅是service

[[email protected] ~]# systemctl list-unit-files

UNIT FILE STATE

proc-sys-fs-binfmt_misc.automount static

dev-hugepages.mount static

dev-mqueue.mount static

proc-sys-fs-binfmt_misc.mount static

sys-fs-fuse-connections.mount static

sys-kernel-config.mount static

sys-kernel-debug.mount static

tmp.mount disabled

brandbot.path disabled

systemd-ask-password-console.path static

systemd-ask-password-plymouth.path static

…

指定服务是否开机启动

[[email protected] ~]# systemctl enable crond.service 开机启动

[[email protected] ~]# systemctl disable crond.service 开机不启动

Removed symlink /etc/systemd/system/multi-user.target.wants/crond.service.

查看服务的状态

[[email protected] ~]# systemctl status crond.service

● crond.service - Command Scheduler

Loaded: loaded (/usr/lib/systemd/system/crond.service; disabled; vendor preset: enabled)

Active: active (running) since 二 2018-07-17 20:51:53 CST; 10h ago

Main PID: 6851 (crond)

CGroup: /system.slice/crond.service

└─6851 /usr/sbin/crond -n

7月 17 20:51:53 hyc-01-01 systemd[1]: Started Command Scheduler.

7月 17 20:51:53 hyc-01-01 systemd[1]: Starting Command Scheduler...

7月 17 20:51:53 hyc-01-01 crond[6851]: (CRON) INFO (RANDOM_DELAY will be scale....)

7月 17 20:51:53 hyc-01-01 crond[6851]: (CRON) INFO (running with inotify support)

7月 17 20:51:53 hyc-01-01 crond[6851]: (CRON) INFO (@reboot jobs will be run a....)

7月 17 21:04:01 hyc-01-01 crond[6851]: (root) RELOAD (/var/spool/cron/root)

Hint: Some lines were ellipsized, use -l to show in full.

启动和停止服务

[[email protected] ~]# systemctl stop crond 停止服务

[[email protected] ~]# systemctl start crond 启动服务

[[email protected] ~]# systemctl restart crond 重启服务

检测service是否开机启动

[[email protected] ~]# systemctl is-enabled crond

disabled

crond实际为一个软链接，源文件在/usr/lib下，链接文件在/etc/systemd

[[email protected] ~]# systemctl is-enabled crond

disabled

[[email protected] ~]# ls /etc/systemd/system/multi-user.target.wants/crond.service

ls: 无法访问/etc/systemd/system/multi-user.target.wants/crond.service: 没有那个文件或目录

[[email protected] ~]# systemctl enable crond

Created symlink from /etc/systemd/system/multi-user.target.wants/crond.service to /usr/lib/systemd/system/crond.service.

[[email protected] ~]# ls /etc/systemd/system/multi-user.target.wants/crond.service

/etc/systemd/system/multi-user.target.wants/crond.service

10.26 unit介绍

10.27 target介绍