目录
1 linux任务计划cron
Linux任务计划功能的操作都是通过crontab命令来完成的，常用的参数有：
-u：表示指定某个用户，不加-u选项则为当前用户
-e：表示制定计划任务
-l：表示列出计划任务
-r：表示删除计划任务
- 编写任务计划的格式
[root@linux01 ~]# cat /etc/crontab
SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root
# 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格式：分 时 日 月 周 user command
分范围0-59，时范围0-23，日范围1-31，月范围1-12，周1-7
可用格式1-5表示一个范围1到5
可用格式1,2,3表示1或者2或者3
可用格式*/2表示被2整除的数字，比如小时，那就是每隔2小时
- 命令crontab -e打开任务计划编写的配置文件
[root@linux01 ~]# crontab -e
59 16 * * * echo "hello world!" > /tmp/testcron.log
[root@linux01 ~]# date
Sun Oct 28 16:58:41 CST 2018
[root@linux01 ~]# ll /tmp/
total 8
-rwx------. 1 root root 836 Oct 25 08:52 ks-script-wgZ0hw
-rw-r--r-- 1 root root 13 Oct 28 16:59 testcron.log
-rw-------. 1 root root 0 Oct 25 08:45 yum.log
[root@linux01 ~]# cat /tmp/testcron.log
hello world!命令crontab -e实际上是打开了/var/spool/cron/username文件（如果用户是root，则打开的是/var/spool/cron/root）。打开这个文件使用了vim编辑器，所以保存时在命令行模式下输入:wq即可。但是请千万不要直接去编辑那个文件，否则会出错，所以一定要使用命令crontab -e来编辑文件/var/spool/cron/username
- 命令crontab -e -u user，指定user用户打开任务计划编写的配置文件
[root@linux01 ~]# useradd user
[root@linux01 ~]# crontab -e -u user
添加以下命令
10 17 * * * echo "hello world!" > /tmp/usercron.log
[root@linux01 ~]# ll /tmp/
total 12
-rwx------. 1 root root 836 Oct 25 08:52 ks-script-wgZ0hw
-rw-r--r-- 1 root root 13 Oct 28 16:59 testcron.log
-rw-r--r-- 1 user user 13 Oct 28 17:10 usercron.log
-rw-------. 1 root root 0 Oct 25 08:45 yum.log
[root@linux01 ~]# cat /tmp/usercron.log
hello world!- 命令crontab -l，查看任务计划列表（默认是当前用户）
[root@linux01 ~]# crontab -l
59 16 * * * echo "hello world!" > /tmp/testcron.log- 命令crontab -l -u user，查看user用户任务计划列表
[root@linux01 ~]# crontab -l -u user
10 17 * * * echo "hello world!" > /tmp/usercron.log- 命令crontab -r，清空任务计划列表（默认是当前用户）
[root@linux01 ~]# crontab -l
59 16 * * * echo "hello world!" > /tmp/testcron.log
[root@linux01 ~]# crontab -r
[root@linux01 ~]# crontab -l
no crontab for root- 命令crontab -r -u user，清空user用户任务计划列表
[root@linux01 ~]# crontab -l -u user
10 17 * * * echo "hello world!" > /tmp/usercron.log
[root@linux01 ~]# crontab -r -u user
[root@linux01 ~]# crontab -l -u user
no crontab for user- crond服务启动：systemctl start crond.service
[root@linux01 ~]# systemctl start crond.service- 查看crond服务是否启动：systemctl status crond.service
[root@linux01 ~]# systemctl status crond.service
2 chkconfig工具
CentOS 6上的服务管理工具为chkconfig，Linux系统所有的预设服务都可以通过查看/etc/init.d/目录得到
[root@linux01 ~]# ls /etc/init.d/
functions netconsole network README因为CentOS 7已经不再延续CentOS 6版本的服务管理方案了。但是我们依然可以继续使用chkconfig这个命令，系统的预设服务都可以通过这样的命令实现：service 服务名 start|stop|restart；可以使用命令/etc/init.d/服务名 start
- 命令chkconfig --list列出所有的服务及其每个级别的开启状态
[root@linux01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off- 因为chkconfig命令是centos6以前的命令，其中以上的数字0-6代表系统运行级别：
0 - halt (Do NOT set initdefault to this)
运行级别0：系统停机状态，系统默认运行级别不能设为0，否则不能正常启动
1 - Single user mode
运行级别1：单用户工作状态，root权限，用于系统维护，禁止远程登陆
2 - Multiuser, without NFS (The same as 3, if you do not have networking)
运行级别2：多用户状态(没有NFS)
3 - Full multiuser mode
运行级别3：完全的多用户状态(有NFS)，登陆后进入控制台命令行模式
4 - unused
运行级别4：系统未使用，保留
5 - X11
运行级别5：X11控制台，登陆后进入图形GUI模式
6 - reboot (Do NOT set initdefault to this)
运行级别6：系统正常关闭并重启，默认运行级别不能设为6，否则不能正常启动
- 关闭运行级别3的network服务
[root@linux01 ~]# chkconfig --level 3 network off
[root@linux01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:off 4:on 5:on 6:off- 关闭运行级别345的network服务
[root@linux01 ~]# chkconfig --level 345 network off
[root@linux01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:off 4:off 5:off 6:off- 把network服务从系统服务删除
[root@linux01 ~]# chkconfig --del network
[root@linux01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off- 将network服务加到系统服务
[root@linux01 ~]# chkconfig --add network
[root@linux01 ~]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off- /etc/init.d下自定义一个启动脚本
[root@linux01 init.d]# cp network test
[root@linux01 init.d]# chkconfig --add test
[root@linux01 init.d]# chkconfig --list
Note: This output shows SysV services only and does not include native
systemd services. SysV configuration data might be overridden by native
systemd configuration.
If you want to list systemd services use 'systemctl list-unit-files'.
To see services enabled on particular target use
'systemctl list-dependencies [target]'.
netconsole 0:off 1:off 2:off 3:off 4:off 5:off 6:off
network 0:off 1:off 2:on 3:on 4:on 5:on 6:off
test 0:off 1:off 2:on 3:on 4:on 5:on 6:off3 systemd管理服务
CentOS 7不使用SysV而改为systemd了，这是因为systemd支持多个服务并发启动，而SysV只能一个一个地启动，这样最终导致的结果是systemd方式启动会快很多
- systemctl list-units --all --type=service列出系统服务
[root@linux01 ~]# systemctl list-units --all --type=service
UNIT LOAD ACTIVE SUB DESCRIPTION
auditd.service loaded active running Security Auditing Service
cpupower.service loaded inactive dead Configure CPU power related setti
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 tables
emergency.service loaded inactive dead Emergency Shell
● exim.service not-found inactive dead exim.service
firewalld.service loaded active running firewalld - dynamic firewall daem
[email protected] loaded active running Getty on tty1
● ip6tables.service not-found inactive dead ip6tables.service
● ipset.service not-found inactive dead ipset.service
● iptables.service not-found inactive dead iptables.service
irqbalance.service loaded active running irqbalance daemon
kdump.service loaded active exited Crash recovery kernel arming
kmod-static-nodes.service loaded active exited Create list of required static de
microcode.service loaded inactive dead Load CPU microcode update
network.service loaded active exited LSB: Bring up/down networking
NetworkManager-wait-online.service loaded active exited Network Manager Wait Online几个常用的服务相关的命令
- systemctl enable crond.service //让服务开机启动
[root@linux01 ~]# systemctl enable crond.service- systemctl disable crond //禁止开机启动
[root@linux01 ~]# systemctl disabledcrond.service- systemctl status crond //查看状态
[root@linux01 ~]# systemctl status crond.service
- systemctl stop crond //停止服务
[root@linux01 ~]# systemctl stop crond.service
- systemctl start crond与 //启动服务
[root@linux01 ~]# systemctl startcrond.service
- systemctl restart crond //重启服务
[root@linux01 ~]# systemctl restart crond.service- systemctl is-enabled crond //检查服务是否开机启动
[root@linux01 ~]# systemctl is-enabled crond.service
enabled4 unit介绍
- ls /usr/lib/systemd/system //系统所有unit，分为以下类型
[root@linux01 ~]# ls /usr/lib/systemd/system
- ls -l runlevel* 列出0-6的级别
[root@linux01 ~]# ls -l /usr/lib/systemd/system/runlevel*
每种类型的文件都为一个unit，正是这些unit才组成了系统的各个资源（各个服务、各个设备等）
service 系统服务
target 多个unit组成的组
device 硬件设备
mount 文件系统挂载点
automount 自动挂载点
path 文件或路径
scope 不是由systemd启动的外部进程
slice 进程组
snapshot systemd快照
socket 进程间通信套接字
swap swap文件
timer 定时器
unit相关的命令
- systemctl list-units //列出正在运行的unit
[root@linux01 ~]# systemctl list-units
UNIT LOAD ACTIVE SUB DESCRIPTION
proc-sys-fs-binfmt_misc.automount loaded active waiting Arbitrary Executable File Formats
sys-devices-pci0000:00-0000:00:07.1-ata2-host2-target2:0:0-2:0:0:0-block-sr0.device loaded a
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda-sda1.device loaded a
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda-sda2.device loaded a
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda-sda3.device loaded a
sys-devices-pci0000:00-0000:00:10.0-host0-target0:0:0-0:0:0:0-block-sda.device loaded active
sys-devices-pci0000:00-0000:00:11.0-0000:02:01.0-net-ens33.device loaded active plugged 82
sys-devices-pci0000:00-0000:00:11.0-0000:02:02.0-sound-card0.device loaded active plugged
sys-devices-platform-floppy.0-block-fd0.device loaded active plugged /sys/devices/platform
sys-devices-platform-serial8250-tty-ttyS2.device loaded active plugged /sys/devices/platfo
sys-devices-platform-serial8250-tty-ttyS3.device loaded active plugged /sys/devices/platfo
sys-devices-pnp0-00:06-tty-ttyS0.device loaded active plugged /sys/devices/pnp0/00:06/tty/
sys-devices-pnp0-00:07-tty-ttyS1.device loaded active plugged /sys/devices/pnp0/00:07/tty/
sys-module-configfs.device loaded active plugged /sys/module/configfs
sys-subsystem-net-devices-ens33.device loaded active plugged 82545EM Gigabit Ethernet Cont
-.mount loaded active mounted /- systemctl list-units --all //列出所有，包括失败的或者inactive的
[root@linux01 ~]# systemctl list-units --all
UNIT LOAD ACTIVE SUB DESCRIPTION
proc-sys-fs-binfmt_misc.automount loaded active waiting Arbitrary Executable File F
dev-cdrom.device loaded active plugged VMware_Virtual_IDE_CDROM_Driv
dev-disk-by\x2did-ata\x2dVMware_Virtual_IDE_CDROM_Drive_10000000000000000001.device loaded
dev-disk-by\x2dlabel-CentOS\x5cx207\x5cx20x86_64.device loaded active plugged VMwar
dev-disk-by\x2dpath-pci\x2d0000:00:07.1\x2data\x2d2.0.device loaded active plugged
dev-disk-by\x2dpath-pci\x2d0000:00:10.0\x2dscsi\x2d0:0:0:0.device loaded active plugg
dev-disk-by\x2dpath-pci\x2d0000:00:10.0\x2dscsi\x2d0:0:0:0\x2dpart1.device loaded activ
dev-disk-by\x2dpath-pci\x2d0000:00:10.0\x2dscsi\x2d0:0:0:0\x2dpart2.device loaded activ
dev-disk-by\x2dpath-pci\x2d0000:00:10.0\x2dscsi\x2d0:0:0:0\x2dpart3.device loaded activ
dev-disk-by\x2duuid-2018\x2d05\x2d03\x2d21\x2d07\x2d04\x2d00.device loaded active plu
dev-disk-by\x2duuid-36a0e938\x2d9ce7\x2d4057\x2dbe14\x2d67b1a1901480.device loaded acti
dev-disk-by\x2duuid-6acf1896\x2d1b81\x2d471a\x2db278\x2d828cab45c8ed.device loaded acti
dev-disk-by\x2duuid-df1a0773\x2d646a\x2d4743\x2dbede\x2d08f050362dc4.device loaded acti
dev-fd0.device loaded active plugged /dev/fd0
dev-sda.device loaded active plugged VMware_Virtual_S
dev-sda1.device loaded active plugged VMware_Virtual_S 1
dev-sda2.device loaded active plugged VMware_Virtual_S 2
dev-sda3.device loaded active plugged VMware_Virtual_S 3
dev-sr0.device loaded active plugged VMware_Virtual_IDE_CDROM_Driv
dev-ttyS0.device loaded active plugged /dev/ttyS0
dev-ttyS1.device loaded active plugged /dev/ttyS1
dev-ttyS2.device loaded active plugged /dev/ttyS2
dev-ttyS3.device loaded active plugged /dev/ttyS3- systemctl list-units --all --state=inactive //列出inactive的unit
[root@linux01 ~]# systemctl list-units --all --state=inactive
UNIT LOAD ACTIVE SUB DESCRIPTION
proc-sys-fs-binfmt_misc.mount loaded inactive dead Arbitrary Executable File Forma
sys-fs-fuse-connections.mount loaded inactive dead FUSE Control File System
systemd-ask-password-console.path loaded inactive dead Dispatch Password Requests to C
cpupower.service loaded inactive dead Configure CPU power related set
● 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 table
emergency.service loaded inactive dead Emergency Shell
● exim.service not-found inactive dead exim.service
● ip6tables.service not-found inactive dead ip6tables.service
● ipset.service not-found inactive dead ipset.service
● iptables.service not-found inactive dead iptables.service
microcode.service loaded inactive dead Load CPU microcode update
plymouth-quit-wait.service loaded inactive dead Wait for Plymouth Boot Screen t
plymouth-quit.service loaded inactive dead Terminate Plymouth Boot Screen
plymouth-read-write.service loaded inactive dead Tell Plymouth To Write Out Runt
plymouth-start.service loaded inactive dead Show Plymouth Boot Screen
rc-local.service loaded inactive dead /etc/rc.d/rc.local Compatibilit
rescue.service loaded inactive dead Rescue Shell
rhel-autorelabel.service loaded inactive dead Relabel all filesystems, if nec
rhel-configure.service loaded inactive dead Reconfigure the system on admin
rhel-loadmodules.service loaded inactive dead Load legacy module configuratio
[email protected] loaded inactive dead Migrate loca
● sendmail.service not-found inactive dead sendmail.service
sshd-keygen.service loaded inactive dead OpenSSH Server Key Generation
● syslog.service not-found inactive dead syslog.service- systemctl list-units --type=service//列出状态为active的service
[root@linux01 ~]# systemctl list-units --type=service
UNIT LOAD ACTIVE SUB DESCRIPTION
auditd.service loaded active running Security Auditing Service
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 daemon
[email protected] loaded active running Getty on tty1
irqbalance.service loaded active running irqbalance daemon
kdump.service loaded active exited Crash recovery kernel arming
kmod-static-nodes.service loaded active exited Create list of required static devi
network.service loaded active exited LSB: Bring up/down networking
NetworkManager-wait-online.service loaded active exited Network Manager Wait Online
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-domainname.service loaded active exited Read and set NIS domainname from /e
rhel-import-state.service loaded active exited Import network configuration from i
rhel-readonly.service loaded active exited Configure read-only root support
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 Storage
systemd-journald.service loaded active running Journal Service- systemctl is-active crond.service //查看某个服务是否为active
[root@linux01 ~]# systemctl is-active crond.service
active- systemctl is-enable crond.service //查看某个服务是否为enable
[root@linux01 ~]# systemctl is-enabled crond.service
enabled5 target介绍
系统为了方便管理用target来管理unit
- systemctl list-unit-files --type=target 查看当前系统的所有 target
[root@linux01 ~]# systemctl list-unit-files --type=target
- systemctl list-dependencies multi-user.target //查看指定target下面有哪些unit
[root@linux01 ~]# systemctl list-dependencies multi-user.target
- systemctl get-default 查看系统默认的target
[root@linux01 ~]# systemctl get-default
multi-user.target- systemctl set-default multi-user.target 设置默认的target
[root@linux01 ~]# systemctl set-default multi-user.target
Removed symlink /etc/systemd/system/default.target.
Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target.上面提到的multi-user.target等同于CentOS 6的运行级别3，其实还有其他几个target对应0~6运行级别
一个service属于一种类型的unit
多个unit组成了一个target
一个target里面包含了多个service，可以查看文件/usr/lib/systemd/system/sshd.service里面[install]部分的内容，它就定义了该service属于哪一个target
cat /usr/lib/systemd/system/sshd.service //看[install]部分
[root@linux01 ~]# systemctl set-default multi-user.target
Removed symlink /etc/systemd/system/default.target.
Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target.[root@linux01 ~]# cat /usr/lib/systemd/system/sshd.service
[Unit]
Description=OpenSSH server daemon
Documentation=man:sshd(8) man:sshd_config(5)
After=network.target sshd-keygen.service
Wants=sshd-keygen.service
[Service]
Type=notify
EnvironmentFile=/etc/sysconfig/sshd
ExecStart=/usr/sbin/sshd -D $OPTIONS
ExecReload=/bin/kill -HUP $MAINPID
KillMode=process
Restart=on-failure
RestartSec=42s
[Install]
WantedBy=multi-user.target扩展
1. anacron http://blog.csdn.net/strikers1982/article/details/4787226
2. xinetd服(默认机器没有安装这个服务，需要yum install xinetd安装）http://blog.sina.com.cn/s/blog_465bbe6b010000vi.html
3. systemd自定义启动脚本 http://www.jb51.net/article/100457.htm