本文介绍了如何使用vmstat、dmesg等命令监控Linux系统的CPU、内存等资源使用情况，并展示了如何通过crond服务管理和配置用户的定时任务。
一、系统资源查看
1.vmstat命令监控系统资源
###监控系统资源，每两秒刷新一次，监控三次
###主要关注空余内存和cpu的空闲率两个指标
[root@wenhaijin ~]# vmstat 2 3
procs -----------memory---------- ---swap-- -----io---- --system-- -----cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
0 0 0 374888 136028 368312 0 0 2 18 12 6 2 2 96 0 0
0 0 0 374764 136032 368340 0 0 0 38 1231 569 2 2 96 0 0
0 0 0 368484 136032 371100 0 0 0 0 1268 612 1 2 97 0 0
[root@wenhaijin ~]#
2.开机时内核检测信息
###系统启动信息非常多，一般使用管道符进行查看
###查看系统CPU的详细信息
[root@wenhaijin ~]# dmesg | grep CPU
SMP: Allowing 1 CPUs, 0 hotplug CPUs
NR_CPUS:4096 nr_cpumask_bits:1 nr_cpu_ids:1 nr_node_ids:1
PERCPU: Embedded 30 pages/cpu @ffff880002200000 s91224 r8192 d23464 u2097152
mce: CPU supports 10 MCE banks
CPU0: Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz stepping 04
Performance Events: unsupported p6 CPU model 62 no PMU driver, software events only.
Brought up 1 CPUs
microcode: CPU0 sig=0x306e4, pf=0x1, revision=0x1
CPU 0: hi: 0, btch: 1 usd: 0
CPU 0: hi: 186, btch: 31 usd: 70
###查看系统网卡信息
[root@wenhaijin ~]# dmesg | grep eth03.free命令查看内存使用状态
###free查看内存使用状况，以字节为单位
[root@wenhaijin ~]# free
total used free shared buffers cached
Mem: 1922244 1560212 362032 0 136092 371392
-/+ buffers/cache: 1052728 869516
Swap: 0 0 0
###习惯性地，加-m 转化为MB,人性化显示
[root@wenhaijin ~]# free -m
total used free shared buffers cached
Mem: 1877 1517 360 0 132 359
-/+ buffers/cache: 1024 852
Swap: 0 0 0
缓冲和缓存的区别
4.查看cpu信息
cat /proc/cpuinfo
比dmesg | grep CPU详细
###cpu主频（2.60GHz）和二级缓存大小（cache size: 20480 KB）比较具有参考意义，参数越大，cpu越好
[root@wenhaijin ~]# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 62
model name : Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz
stepping : 4
microcode : 1
cpu MHz : 2599.996
cache size : 20480 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss syscall nx pdpe1gb rdtscp lm constant_tsc up rep_good unfair_spinlock pni pclmulqdq ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm xsaveopt
bogomips : 5199.99
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
power management:
5.uptime命令
uptime命令显示系统启动时间和平均负载，也就是top命令的第一行。w命令也可以看到这个信息
###top命令
[root@wenhaijin ~]# top
top - 22:31:58 up 25 days, 23:08, 17 users, load average: 0.05, 0.07, 0.10
Tasks: 227 total, 1 running, 182 sleeping, 0 stopped, 44 zombie
Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 1922244k total, 1557164k used, 365080k free, 136136k buffers
Swap: 0k total, 0k used, 0k free, 371420k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1 root 20 0 19356 388 88 S 0.0 0.0 6:16.70 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0
4 root 20 0 0 0 0 S 0.0 0.0 0:00.55 ksoftirqd/0
5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 stopper/0
6 root RT 0 0 0 0 S 0.0 0.0 0:03.00 watchdog/0
7 root 20 0 0 0 0 S 0.0 0.0 1:56.05 events/0
8 root 20 0 0 0 0 S 0.0 0.0 0:00.00 events/0
9 root 20 0 0 0 0 S 0.0 0.0 0:00.00 events_long/0
10 root 20 0 0 0 0 S 0.0 0.0 0:00.00 events_power_ef
11 root 20 0 0 0 0 S 0.0 0.0 0:00.00 cgroup
12 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khelper
13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 netns
14 root 20 0 0 0 0 S 0.0 0.0 0:00.00 async/mgr
15 root 20 0 0 0 0 S 0.0 0.0 0:00.00 pm
16 root 20 0 0 0 0 S 0.0 0.0 0:05.08 sync_supers
17 root 20 0 0 0 0 S 0.0 0.0 0:05.77 bdi-default
###w命令
[root@wenhaijin ~]# w
22:32:01 up 25 days, 23:08, 17 users, load average: 0.05, 0.07, 0.10
USER TTY FROM LOGIN@ IDLE JCPU PCPU WHAT
root pts/0 220.231.189.27 22Apr17 25days 0.08s 0.00s -bash
root pts/1 113.87.160.169 23Apr17 24days 0.02s 0.02s -bash
root pts/2 113.87.163.128 24Apr17 22days 0.02s 0.02s -bash
root pts/3 113.87.160.227 25Apr17 21days 9:32 0.01s mysql -uroot -p
root pts/4 220.231.189.27 03May17 14days 0.09s 0.09s -bash
root pts/5 220.231.189.27 03May17 14days 0.03s 0.03s -bash
root pts/6 113.87.162.197 03May17 13days 0.03s 0.03s -bash
root pts/7 220.231.189.27 05May17 12days 0.02s 0.02s -bash
root pts/8 113.87.163.32 05May17 11days 0.02s 0.02s -bash
root pts/9 220.231.189.27 06May17 11days 0.10s 0.10s -bash
root pts/10 220.231.189.27 06May17 11days 0.01s 0.01s -bash
root pts/11 220.231.189.27 06May17 11days 0.02s 0.02s -bash
root pts/13 220.231.189.27 11May17 6days 0.04s 0.04s -bash
root pts/14 183.39.156.22 Sun08 3days 0.11s 0.03s ntsysv
root pts/17 183.39.156.22 Sun22 2days 0.00s 0.00s -bash
root pts/60 61.141.253.193 22:03 28:06 0.00s 0.00s -bash
root pts/62 61.141.253.193 22:21 0.00s 0.07s 0.00s w
[root@wenhaijin ~]#
###uptime命令
[root@wenhaijin ~]# uptime
22:33:43 up 25 days, 23:10, 17 users, load average: 0.24, 0.11, 0.11
[root@wenhaijin ~]#
6.查看系统与内核相关信息
###查看内核所有相关信息
[root@wenhaijin ~]# uname -a
Linux wenhaijin 2.6.32-573.22.1.el6.x86_64 #1 SMP Wed Mar 23 03:35:39 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux
###查看内核版本信息
[root@wenhaijin ~]# uname -r
2.6.32-573.22.1.el6.x86_64
###查看系统名称
[root@wenhaijin ~]# uname -s
Linux
[root@wenhaijin ~]#
7.判断当前操作系统位数
不能查看系统内部命令，只有通过file命令查询系统外部命令，然后间接地查询出操作系统位数
[root@wenhaijin ~]# file /bin/ls
/bin/ls: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped
[root@wenhaijin ~]#
8.列出进程打开或使用的文件信息
[root@wenhaijin ~]# ps aux
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.0 19356 388 ? Ss Apr21 6:16 /sbin/init
root 2 0.0 0.0 0 0 ? S Apr21 0:00 [kthreadd]
root 3 0.0 0.0 0 0 ? S Apr21 0:00 [migration/0]
root 4 0.0 0.0 0 0 ? S Apr21 0:00 [ksoftirqd/0]
root 5 0.0 0.0 0 0 ? S Apr21 0:00 [stopper/0]
root 6 0.0 0.0 0 0 ? S Apr21 0:03 [watchdog/0]
root 7 0.0 0.0 0 0 ? S Apr21 1:56 [events/0]
root 8 0.0 0.0 0 0 ? S Apr21 0:00 [events/0]
root 9 0.0 0.0 0 0 ? S Apr21 0:00 [events_long/0]
root 10 0.0 0.0 0 0 ? S Apr21 0:00 [events_power_]
root 11 0.0 0.0 0 0 ? S Apr21 0:00 [cgroup]
root 12 0.0 0.0 0 0 ? S Apr21 0:00 [khelper]
root 13 0.0 0.0 0 0 ? S Apr21 0:00 [netns]
root 14 0.0 0.0 0 0 ? S Apr21 0:00 [async/mgr]
root 15 0.0 0.0 0 0 ? S Apr21 0:00 [pm]
root 16 0.0 0.0 0 0 ? S Apr21 0:05 [sync_supers]
root 17 0.0 0.0 0 0 ? S Apr21 0:05 [bdi-default]
root 18 0.0 0.0 0 0 ? S Apr21 0:00 [kintegrityd/0]
root 19 0.0 0.0 0 0 ? S Apr21 0:09 [kblockd/0]
root 20 0.0 0.0 0 0 ? S Apr21 0:00 [kacpid]
root 21 0.0 0.0 0 0 ? S Apr21 0:00 [kacpi_notify]
root 22 0.0 0.0 0 0 ? S Apr21 0:00 [kacpi_hotplug]
root 23 0.0 0.0 0 0 ? S Apr21 0:00 [ata_aux]
root 24 0.0 0.0 0 0 ? S Apr21 0:00 [ata_sff/0]
root 25 0.0 0.0 0 0 ? S Apr21 0:00 [ksuspend_usbd]
root 26 0.0 0.0 0 0 ? S Apr21 0:00 [khubd]
root 27 0.0 0.0 0 0 ? S Apr21 0:00 [kseriod]
root 28 0.0 0.0 0 0 ? S Apr21 0:00 [md/0]
root 29 0.0 0.0 0 0 ? S Apr21 0:00 [md_misc/0]
root 30 0.0 0.0 0 0 ? S Apr21 0:00 [linkwatch]
root 32 0.0 0.0 0 0 ? S Apr21 0:00 [khungtaskd]
root 33 0.0 0.0 0 0 ? S Apr21 0:04 [kswapd0]
root 34 0.0 0.0 0 0 ? SN Apr21 0:00 [ksmd]
root 35 0.0 0.0 0 0 ? SN Apr21 0:03 [khugepaged]
root 36 0.0 0.0 0 0 ? S Apr21 0:00 [aio/0]
root 37 0.0 0.0 0 0 ? S Apr21 0:00 [crypto/0]
root 44 0.0 0.0 0 0 ? S Apr21 0:00 [kthrotld/0]
root 46 0.0 0.0 0 0 ? S Apr21 0:00 [kpsmoused]
root 47 0.0 0.0 0 0 ? S Apr21 0:00 [usbhid_resume]
root 48 0.0 0.0 0 0 ? S Apr21 0:00 [deferwq]
root 80 0.0 0.0 0 0 ? S Apr21 0:00 [kdmremove]
root 81 0.0 0.0 0 0 ? S Apr21 0:00 [kstriped]
root 159 0.0 0.0 0 0 ? S Apr21 0:00 [scsi_eh_0]
root 2513 0.0 0.0 0 0 ? Zs May16 0:00 [log] <defunct>
root 2709 0.0 0.0 8520 872 ? Ss May16 0:00 in.telnetd: CPE
root 2725 0.0 0.0 0 0 ? Zs May16 0:00 [log] <defunct>
root 2874 0.0 0.2 98348 4116 ? Ss 22:21 0:00 sshd: root@pts/
root 2931 0.0 0.0 8520 872 ? Ss May16 0:00 in.telnetd: CPE
###按照进程号查看sshd进程打开或应用了哪些文件
[root@wenhaijin ~]# lsof -p 2874
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
sshd 2874 root cwd DIR 252,1 4096 2 /
sshd 2874 root rtd DIR 252,1 4096 2 /
sshd 2874 root txt REG 252,1 546680 1059312 /usr/sbin/sshd
sshd 2874 root DEL REG 0,4 26343731 /dev/zero
sshd 2874 root mem REG 252,1 18600 268710 /lib64/security/pam_limits.so
sshd 2874 root mem REG 252,1 10224 268708 /lib64/security/pam_keyinit.so
sshd 2874 root mem REG 252,1 10240 268713 /lib64/security/pam_loginuid.so
sshd 2874 root mem REG 252,1 18672 268726 /lib64/security/pam_selinux.so
sshd 2874 root mem REG 252,1 41088 1051837 /usr/lib64/libcrack.so.2.8.1
sshd 2874 root mem REG 252,1 14432 262186 /lib64/security/pam_cracklib.so
sshd 2874 root mem REG 252,1 6040 268720 /lib64/security/pam_permit.so
sshd 2874 root mem REG 252,1 10200 268712 /lib64/security/pam_localuser.so
sshd 2874 root mem REG 252,1 10208 268719 /lib64/security/pam_nologin.so
sshd 2874 root mem REG 252,1 5952 262194 /lib64/security/pam_deny.so
sshd 2874 root mem REG 252,1 14384 268731 /lib64/security/pam_succeed_if.so
sshd 2874 root mem REG 252,1 51960 268737 /lib64/security/pam_unix.so
sshd 2874 root mem REG 252,1 18592 268699 /lib64/security/pam_env.so
sshd 2874 root mem REG 252,1 14488 268728 /lib64/security/pam_sepermit.so
sshd 2874 root mem REG 252,1 65928 262212 /lib64/libnss_files-2.12.so
sshd 2874 root mem REG 252,1 47168 262192 /lib64/librt-2.12.so
sshd 2874 root mem REG 252,1 247192 270871 /lib64/libnspr4.so
sshd 2874 root mem REG 252,1 17128 270873 /lib64/libplds4.so
sshd 2874 root mem REG 252,1 21288 270872 /lib64/libplc4.so
sshd 2874 root mem REG 252,1 182112 1051868 /usr/lib64/libnssutil3.so
sshd 2874 root mem REG 252,1 145936 262189 /lib64/libpthread-2.12.so
sshd 2874 root mem REG 252,1 12592 262226 /lib64/libkeyutils.so.1.3
sshd 2874 root mem REG 252,1 46368 270917 /lib64/libkrb5support.so.0.1
sshd 2874 root mem REG 252,1 472064 262173 /lib64/libfreebl3.so
sshd 2874 root mem REG 252,1 1926520 262157 /lib64/libc-2.12.so
sshd 2874 root mem REG 252,1 1302712 1063502 /usr/lib64/libnss3.so
sshd 2874 root mem REG 252,1 17256 270919 /lib64/libcom_err.so.2.1
sshd 2874 root mem REG 252,1 177520 270918 /lib64/libk5crypto.so.3.1
sshd 2874 root mem REG 252,1 948840 270920 /lib64/libkrb5.so.3.3
sshd 2874 root mem REG 252,1 280520 270921 /lib64/libgssapi_krb5.so.2.2
sshd 2874 root mem REG 252,1 113952 270890 /lib64/libresolv-2.12.so
sshd 2874 root mem REG 252,1 43392 262181 /lib64/libcrypt-2.12.so
sshd 2874 root mem REG 252,1 116368 262217 /lib64/libnsl-2.12.so
sshd 2874 root mem REG 252,1 91096 270868 /lib64/libz.so.1.2.3
sshd 2874 root mem REG 252,1 17520 262197 /lib64/libutil-2.12.so
sshd 2874 root mem REG 252,1 1969952 1067552 /usr/lib64/libcrypto.so.1.0.1e
sshd 2874 root mem REG 252,1 124640 270915 /lib64/libselinux.so.1
sshd 2874 root mem REG 252,1 22536 262171 /lib64/libdl-2.12.so
sshd 2874 root mem REG 252,1 58480 262183 /lib64/libpam.so.0.82.2
sshd 2874 root mem REG 252,1 115536 262161 /lib64/libaudit.so.1.0.0
sshd 2874 root mem REG 252,1 40792 262241 /lib64/libwrap.so.0.7.6
sshd 2874 root mem REG 252,1 12688 262252 /lib64/libfipscheck.so.1.1.0
sshd 2874 root mem REG 252,1 157072 262151 /lib64/ld-2.12.so
sshd 2874 root DEL REG 0,4 26343637 /dev/zero
sshd 2874 root 0u CHR 1,3 0t0 3839 /dev/null
sshd 2874 root 1u CHR 1,3 0t0 3839 /dev/null
sshd 2874 root 2u CHR 1,3 0t0 3839 /dev/null
sshd 2874 root 3r IPv4 26343616 0t0 TCP 172.18.69.197:ssh->61.141.253.193:34927 (ESTABLISHED)
sshd 2874 root 4w unix 0xffff88002f845240 0t0 26343740 socket
sshd 2874 root 5u FIFO 0,8 0t0 26343743 pipe
sshd 2874 root 6w FIFO 0,8 0t0 26343743 pipe
sshd 2874 root 7u CHR 5,2 0t0 5452 /dev/ptmx
sshd 2874 root 9u CHR 5,2 0t0 5452 /dev/ptmx
sshd 2874 root 10u CHR 5,2 0t0 5452 /dev/ptmx
[root@wenhaijin ~]#
###按照字符串查找init进程打开或应用了哪些文件
[root@wenhaijin ~]# lsof -c init
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
init 1 root cwd DIR 252,1 4096 2 /
init 1 root rtd DIR 252,1 4096 2 /
init 1 root txt REG 252,1 150352 655401 /sbin/init
init 1 root mem REG 252,1 65928 262212 /lib64/libnss_files-2.12.so
init 1 root mem REG 252,1 1926520 262157 /lib64/libc-2.12.so
init 1 root mem REG 252,1 93320 270891 /lib64/libgcc_s-4.4.7-20120601.so.1
init 1 root mem REG 252,1 47168 262192 /lib64/librt-2.12.so
init 1 root mem REG 252,1 145936 262189 /lib64/libpthread-2.12.so
init 1 root mem REG 252,1 268232 269502 /lib64/libdbus-1.so.3.4.0
init 1 root mem REG 252,1 39896 265469 /lib64/libnih-dbus.so.1.0.0
init 1 root mem REG 252,1 101920 265471 /lib64/libnih.so.1.0.0
init 1 root mem REG 252,1 157072 262151 /lib64/ld-2.12.so
init 1 root 0u CHR 1,3 0t0 3839 /dev/null
init 1 root 1u CHR 1,3 0t0 3839 /dev/null
init 1 root 2u CHR 1,3 0t0 3839 /dev/null
init 1 root 3r FIFO 0,8 0t0 6706 pipe
init 1 root 4w FIFO 0,8 0t0 6706 pipe
init 1 root 5r DIR 0,10 0 1 inotify
init 1 root 6r DIR 0,10 0 1 inotify
init 1 root 7u unix 0xffff880037b61400 0t0 6707 socket
[root@wenhaijin ~]#
二、系统定时任务
1.使用crond服务管理与访问控制
若未安装cron服务，采用下面的命令进行安装
[root@myserver sbin]# yum -y install vixie-cron
[root@myserver sbin]# chkconfig crond on
[root@myserver sbin]# chkconfig --list | grep crond
crond 0:off 1:off 2:on 3:on 4:on 5:on 6:off
[root@myserver sbin]# ps aux | grep crond
root 15102 0.0 0.0 117296 1252 ? Ss 23:38 0:00 crond
root 15108 0.0 0.0 103256 856 pts/0 S+ 23:39 0:00 grep crond
[root@myserver sbin]#
2.用户的crontab设置
5个“*”的含义如下
特殊符号
具体配置示例如下
3.写一个定时备份系统文件的例子（未完待续）
写完后将脚本加到定时任务配置文件中执行
[root@myserver sbin]# crontab -e
no crontab for root - using an empty one
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