Linux之基础命令

1. ls：显示文件

[wyb@localhost tmp]$ ls
a  a.txt
[wyb@localhost tmp]$ ls -l
total 4
drwxr-xr-x. 2 wyb root 4096 Apr 17 18:23 a
-rw-r--r--. 1 wyb root    0 Apr 17 18:23 a.txt
[wyb@localhost tmp]$ ls -a
.  ..  a  a.txt  .esd-500  .ICE-unix
[wyb@localhost tmp]$ ls -al
total 20
drwxrwxrwt.  5 root root 4096 Apr 17 18:23 .
dr-xr-xr-x. 22 root root 4096 Apr 17 16:31 ..
drwxr-xr-x.  2 wyb  root 4096 Apr 17 18:23 a
-rw-r--r--.  1 wyb  root    0 Apr 17 18:23 a.txt
drwx------.  2 wyb  wyb  4096 Apr 10 19:15 .esd-500
drwxrwxrwt.  2 root root 4096 Apr 17 16:31 .ICE-unix

2. pwd：查看当前工作路径

[wyb@localhost ~]$ pwd  
/home/wyb

3. cd：切换目录

[wyb@localhost ~]$ ls
Desktop  Documents  Downloads  Music  Pictures  Public  Templates  Videos
[wyb@localhost ~]$ cd Desktop/     //相对路径
[wyb@localhost Desktop]$ cd /tmp/a    //绝对路径
[wyb@localhost a]$ pwd
/tmp/a

4. mkdir：新建文件夹

[wyb@localhost tmp]$ ls
a  a.txt
[wyb@localhost tmp]$ mkdir bbb
[wyb@localhost tmp]$ ls
a  a.txt  bbb

5. touch/vim：新建文件

[wyb@localhost tmp]$ ls
a  a.txt  bbb
[wyb@localhost tmp]$ touch bbb.txt
[wyb@localhost tmp]$ ls
a  a.txt  bbb  bbb.txt

5. rm：删除文件

[wyb@localhost tmp]$ ls
a  a.txt  bbb  bbb.txt  c.txt
[wyb@localhost tmp]$ rm c.txt   //删除文件c.txt
[wyb@localhost tmp]$ ls
a  a.txt  bbb  bbb.txt
[wyb@localhost tmp]$ rm a   //删除文件夹a，结果不能删除
rm: cannot remove `a': Is a directory
[wyb@localhost tmp]$ rm -r a   //加上-r才能删除文件夹
[wyb@localhost tmp]$ ls
a.txt  bbb  bbb.txt

6. ifconfig：查看网卡的信息

[wyb@localhost tmp]$ ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:56:B4:10  
          inet addr:192.168.63.131  Bcast:192.168.63.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:29ff:fe56:b410/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:67099 errors:0 dropped:0 overruns:0 frame:0
          TX packets:34939 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:94042525 (89.6 MiB)  TX bytes:1995748 (1.9 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

7. netstat：查找网络连接信息

netstat -l   //listen状态的
netstat -an  //显示所有的连接信息，且以ip地址代替名称
netstat -t   //显示tcp连接信息
netstat -u   //显示udp连接信息
LISTENING   //监听端口状态
ESTABLSHED  //建立连接
CLOSE_WAIT  //对方主动断开连接，此时我方就会变为这个状态，我方要调用close()
TIME_WAIT   //我方主动调用close(),对方收到后变为CLOSE_WAIT
[root@localhost ~]# netstat -l -n
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address               Foreign Address远程         State      
tcp        0      0 0.0.0.0:22                  0.0.0.0:*                   LISTEN  所有ip均可连接22
tcp        0      0 127.0.0.1:631               0.0.0.0:*                   LISTEN
tcp        0      0 127.0.0.1:25                0.0.0.0:*                   LISTEN  只有127.0.0.1连接25端口
tcp        0      0 :::22                       :::*                        LISTEN      
tcp        0      0 ::1:631                     :::*                        LISTEN  
Active UNIX domain sockets (only servers)
Proto RefCnt Flags       Type       State         I-Node Path
unix  2      [ ACC ]     STREAM     LISTENING     14229  public/cleanup
unix  2      [ ACC ]     STREAM     LISTENING     14236  private/tlsmgr
unix  2      [ ACC ]     STREAM     LISTENING     14240  private/rewrite
unix  2      [ ACC ]     STREAM     LISTENING     14244  private/bounce
unix  2      [ ACC ]     STREAM     LISTENING     14248  private/defer

8.nslookup：查看DNS信息

nslookup 查看ip和域名的相互映射
nslookup www.baidu.com   //返回一些信息

9. ping

ping -c 3 www.baidu.com   //指定ping百度3次

10. last：查看近期的登陆信息

[root@localhost ~]# last  

10. find：查找文件

which vim   //查看可执行文件的位置
*which是通过 PATH环境变量到该路径内查找可执行文件，所以基本的功能是寻找可执行文件* 

whereis、locate也可查找文件,它们是使用数据库来搜索数据

find . -name 1.txt  //查找当前文件夹及子目录下的1.txt、
find . -name *.txt  //使用通配符
find /bin -perm 755 //返回的都是755权限的文件  
find /bin -perm 4755  //返回有gid(即s权限)的文件    2是gid
[wyb@localhost tmp]$ sudo find / -name *.log    //根目录下查找名字以log结尾的文件
/var/spool/plymouth/boot.log
/var/log/wpa_supplicant.log
/var/log/dracut.log
/var/log/vmware-tools-upgrader.log
[wyb@localhost ~]$ find /bin -perm 755 | xargs ls -al   //前一个命令的输出作为后一个命令的输入
-rwxr-xr-x. 1 root root    123 Feb 21  2013 /bin/alsaunmute
-rwxr-xr-x. 1 root root  27776 Jun 22  2012 /bin/arch
-rwxr-xr-x. 1 root root  26264 Jun 22  2012 /bin/basename
-rwxr-xr-x. 1 root root 938768 Feb 21  2013 /bin/bash
-rwxr-xr-x. 1 root root  48568 Jun 22  2012 /bin/cat
-rwxr-xr-x. 1 root root  55472 Jun 22  2012 /bin/chgrp
-rwxr-xr-x. 1 root root  52472 Jun 22  2012 /bin/chmod

11. cat/nl

前者显示
后者显示的同时有行号
[wyb@localhost tmp]$ cat > a.txt  //创建文件同时写入数据
this is a.txt
^C
[wyb@localhost tmp]$ cat > b.txt
this is b.txt
^C
[wyb@localhost tmp]$ cat a.txt b.txt > c.txt   //合并文件
[wyb@localhost tmp]$ cat c.txt 
this is a.txt
this is b.txt
[wyb@localhost tmp]$ cat -n c.txt   //获取文件内容切添加行号
 1  this is a.txt
 2  this is b.txt

12. head

[wyb@localhost tmp]$ head /etc/passwd   //默认显示前10行
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown
halt:x:7:0:halt:/sbin:/sbin/halt
mail:x:8:12:mail:/var/spool/mail:/sbin/nologin
uucp:x:10:14:uucp:/var/spool/uucp:/sbin/nologin

[wyb@localhost tmp]$ head -n 4 /etc/passwd  //设置显示前4行
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin

[wyb@localhost tmp]$ head -c 100 d.txt //显示前100个字节
     1  this is a.txt
     2  this is b.txt
this is add content
     1  this is a.txt
     2  this is b.[wyb@localhost tmp]$ 

13. tail

[wyb@localhost tmp]$ tail -f a.txt  //实时显示文件后10行
this is a.txt
111111
aaaaaa
^C

[wyb@localhost tmp]$ tail -n 3 d.txt //显示文件后3行
     1  this is a.txt
     2  this is b.txt
this is add content

[wyb@localhost tmp]$ tail -c 100 d.txt //显示后100个字节
  2     this is b.txt
this is add content
     1  this is a.txt
     2  this is b.txt
this is add content
[wyb@localhost tmp]$ 

14.磁盘

fdisk /dev/sdb
sudo mkfs.ext3 /dev/sdb1
mount -t ext3 -o rw /dev/sdb1 /home/aaa  //-o指定权限

15.finger

finger可以查看用户登录情况

16.时间同步

ntpdate time.nist.gov //需要root权限