Linux基础命令总结(CentOS6.9, CentOS7.3)

Linux基础命令学习总结,随着学习的前进,将不断完善。网友们,有错误之处,请给我留言改正喔,谢谢!

基础操作

<a href="#clear">clear</a> <a href="#hostname">hostname</a> <a href="#tty">tty</a> <a href="#who">who</a> <a href="#whoami">whoami</a> <a href="#w">w</a> <a href="#whatis">whatis</a> <a href="#which">which</a> <a href="#whereis">whereis</a> <a href="#hash">hash</a> <a href="#enable">enable</a> <a href="#alias">alias</a> <a href="#unalias">unalias</a> <a href="#date">date</a> <a href="#clock">clock</a> <a href="#hwclock">hwclock</a> <a href="#cal">cal</a> <a href="#ldd">ldd</a> <a href="#uname">uname</a> <a href="#timedatectl">timedatectl</a> <a href="#screen">screen</a> <a href="#script">script</a> <a href="#chvt">chvt</a> <a href="#man">man</a>


文件、目录、磁盘、文件系统

<a href="#cd">cd</a> <a href="#pwd">pwd</a> <a href="#ls">ls</a> <a href="#cat">cat</a> <a href="#tac">tac</a> <a href="#nl">nl</a> <a href="#head">head</a> <a href="#tail">tail</a> <a href="#less">less</a> <a href="#more">more</a> <a href="#hexdump">hexdump</a> <a href="# od"> od</a> <a href="#cp">cp</a> <a href="#mv">mv</a> <a href="#rm">rm</a> <a href="#mkdir">mkdir</a> <a href="#rmdir">rmdir</a> <a href="#dd">dd</a> <a href="#gedit">gedit</a> <a href="#nano">nano</a> <a href="#file">file</a> <a href="#type">type</a> <a href="#iconv">iconv</a>


用户和组

<a href="#id">id</a> <a href="#getent">getent</a>


BASHELL 特性

<a href="#echo">echo</a> <a href="#history">history</a> <a href="#hash">hash</a> <a href="#history">history</a>


网络属性

<a href="#ifconfig">ifconfig</a> <a href="#ping">ping</a> <a href="#rz">rz</a> <a href="#sz">sz</a>


系统启动,关机

<a href="#exit">exit</a> <a href="#logout">logout</a> <a href="#init">init</a> <a href="#quit">quit</a> <a href="#reboot">reboot</a> <a href="#shutdown">shutdown</a> <a href="#runlevel">runlevel</a> <a href="#halt">halt</a> <a href="#poweroff">poweroff</a>


进程

<a href="#free">free</a> <a href="#lsblk">lsblk</a> <a href="# lscpu"> lscpu</a>


程序包管理

<a href="#rpm">rpm</a> <a href="#.">.</a> <a href="#source">source</a>



<a id="clear">clear</a>

clear the terminal screen 清空屏幕内容

<a id="hostname">hostname</a>

Display the hostname 显示主机名

  • hostname [-s|--short]
    -s | --short Display the shourt host name, This is the hostname cut at the firs dot. 显示短主机名,取第一个点号之前的字符串
[centos6@root ~]# hostname
centos6.zhubiao.science
# -s 取第一个点号之前的字符串作为短主机名
[centos6@root ~]# hostname -s 
centos6

<a id="tty">tty</a>

print the file name of the terminal connected to standard input 显示当前工作终端下的终端的名字

  • 终端分为:
    • 物理终端
      物理控制台:表示为 /dev/console, Linux单用户模式下显示为物理终端
    • 虚拟终端
      系统自带6个虚拟终端,表示为/dev/tty#, #为1-6
    • 图形终端
    • 伪终端
      图形界面打开的命令行接口,通过ssh或telnet协议打开的命令行界面均为伪终端,表现为/dev/pts/#
# 将运行级别切换为单用户模式后,使用的将是物理终端,如下所示,当前运行级别为3的多用户模式,将其切换为1后查看终端。
[root@zb01 ~]# tty
/dev/tty1
[root@zb01 ~]# runlevel #查看运行级别
S 3
[root@zb01 ~]# init 1
...
[root@zb01 /]# runlevel
1 S
[root@zb01 /]# tty
/dev/console

<a id="who">who</a>

Who is logged on 显示当前登录的用户

  • who [options]
    -b #系统登录的时间
    -r #当前运行级别
[centos7@root dir]# who
root     tty1         2017-07-15 16:20
root     pts/0        2017-07-15 07:24 (gateway)
[centos7@root dir]# who -b
         system boot  2017-07-14 20:54
[centos7@root dir]# who -r
         run-level 3  2017-07-14 20:54                   last=5

<a id="whoami">whoami</a>

显示当前登录的用户名

  • who
[centos7@root dir]# whoami
root

<a id="w">w</a>

Show who is logged on and what they are doing. 显示当前登录的用户和正在执行的命令

  • w
[centos7@root dir]# w 
 17:08:16 up 12:09,  2 users,  load average: 0.00, 0.01, 0.05
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
root     tty1                      16:20   47:20   0.04s  0.04s -bash
root     pts/0    gateway          07:24    0.00s  3.05s  0.01s w

<a id="whatis">whatis</a>

查找外部命令的man手册帮助文档所在的章节

  • whatis command #等同于man -f
[centos7@root ~]# whatis ls
ls (1)               - list directory contents
ls (1p)              - list directory contents

[centos7@root ~]# whatis cp
cp (1)               - copy files and directories
cp (1p)              - copy files

[centos7@root ~]# whatis ifconfig
ifconfig (8)         - configure a network interface

[centos7@root ~]# man -f ls
ls (1)               - list directory contents
ls (1p)              - list directory contents

[centos7@root ~]# man -f cp
cp (1)               - copy files and directories
cp (1p)              - copy files

<a id="which">which</a>

按照PATH路径查找命令后显示其完整路径

  • which [options] [command]
    -a 显示命令所有PATH路径
    --skip-alias 不显示别名
[centos6@root test]# which --skip-alias ls
/bin/ls
[centos6@root test]# which -a ls
alias ls='ls --color=auto'
    /bin/ls

<a id="whereis">whereis</a>

查找命令所在路径,源码路径,帮助手册路径
whereis [options] [command]

[centos6@root test]# whereis mysql
mysql: /usr/bin/mysql /usr/lib64/mysql /usr/share/mysql /usr/share/man/man1/mysql.1.gz

[centos6@root test]# whereis -b mysql
mysql: /usr/bin/mysql /usr/lib64/mysql /usr/share/mysql

[centos6@root test]# whereis -m mysql
mysql: /usr/share/man/man1/mysql.1.gz

<a id="cd">cd</a>

Change the shell working dirctory 切换工作目录

  • cd [-P] DIR
    -P 若DIR为符号链接目录,cd DIR切换到实际的工作目录,而不是符号链接目录
    cd - #切换到上一个工作目录
    cd ~ #切换到当前用户的家目录
    cd ~USER #切换到USER用户的家目录,只有root有权限切换到任意用户的家目录
    cd .. #切换到上一级目录
[centos6@root test]# pwd
/root/test
[centos6@root test]# cd ~  
[centos6@root ~]# pwd
/root
[centos6@root ~]# cd -
/root/test
[centos6@root test]# pwd
/root/test
[centos6@root test]# cd ~zb10
[centos6@root zb10]# pwd
/home/zb10
[centos6@root zb10]# cd ..
[centos6@root home]# pwd
/home
[centos6@root home]# 
# -P 切换到实际路径的工作目录下
[centos6@root test]# ll dir
lrwxrwxrwx. 1 root root 6 Jul 15 17:16 dir -> a/b/c/
[centos6@root test]# cd dir
[centos6@root dir]# pwd
/root/test/dir
[centos6@root dir]# cd -
/root/test
[centos6@root test]# cd -P dir
[centos6@root c]# pwd
/root/test/a/b/c

<a id="pwd">pwd</a>

print the name of the current working dirctory 显示当前工作目录

  • pwd [-P]
    -P - 若当前工作目录为符号链接路径,加-P选项显示实际路径
[centos7@root test]# pwd
/root/test  #显示当前工作目录
# -P 显示出实际路径而不是符号链接的路径
[centos7@root test]# mkdir -p a/b/c 
[centos7@root test]# ln -s a/b/c dir  
[centos7@root test]# ll dir
lrwxrwxrwx. 1 root root 5 Jul 15 15:33 dir -> a/b/c
[centos7@root test]# cd dir 
[centos7@root dir]# pwd  
/root/test/dir
[centos7@root dir]# pwd -P  #加了-P选项,显示实际路径
/root/test/a/b/c

<a id="ls">ls</a>

List dirctory contents 列出当前或指定目录(或所有子目录)下的内容

  • ls [options] [dirs]
    - l 列出详细内容
    -a | --all 列出所有内容包括. ..
    -A 列出所有内容,不包括. ..
    -d 仅列出指定的目录
    --full-time 列出完整的修改时间格式
    [centos6@root test]# ls
    

a dir
[centos6@root test]# ls -l
total 4
drwxr-xr-x. 3 root root 4096 Jul 15 17:15 a
lrwxrwxrwx. 1 root root 6 Jul 15 17:16 dir -> a/b/c/
[centos6@root test]# ll
total 4
drwxr-xr-x. 3 root root 4096 Jul 15 17:15 a
lrwxrwxrwx. 1 root root 6 Jul 15 17:16 dir -> a/b/c/
[centos6@root test]# ls -a
. .. a dir
[centos6@root test]# ls -A
a dir
[centos6@root test]# ls /root/test/
a dir
[centos6@root test]# ls --full-time /root/test/
total 4
drwxr-xr-x. 3 root root 4096 2017-07-15 17:15:41.550009093 +0800 a
lrwxrwxrwx. 1 root root 6 2017-07-15 17:16:44.490009154 +0800 dir -> a/b/c/


>### <a id="cat">cat</a>

Concatenate files and print on the standard output # 读取一个或多个文件(也可以从键盘输入) 并输出
* cat [options] [files]
-n # 在每行(包括空行)前面加上行号
-b # 在非空行前面加上行号

[centos7@root dir]# cat /etc/resolv.conf

Generated by NetworkManager

search magedu.com zhubiao.science

nameserver 192.168.17.1

nameserver 172.18.0.1

-n 加入行号,包括空行

[centos7@root dir]# cat -n /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science
3
4 nameserver 192.168.17.1
5
6 nameserver 172.18.0.1

-b非空行前加入行号

[centos7@root dir]# cat -b /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science

 3  nameserver 192.168.17.1
  
 4  nameserver 172.18.0.1

>###<a id="tac">tac</a>

Concatenate and print files #倒叙显示文件内容,即从文件尾页到首页的顺序显示内容
* tac

如正常顺序显示/etc/resolv.conf 如下:

[centos7@root dir]# cat /etc/resolv.conf

Generated by NetworkManager

search magedu.com zhubiao.science

nameserver 192.168.17.1

nameserver 172.18.0.1

使用tac 将倒序输出文件内容,如下:

[centos7@root dir]# tac /etc/resolv.conf
nameserver 172.18.0.1

nameserver 192.168.17.1

search magedu.com zhubiao.science

Generated by NetworkManager


>###<a id="nl">nl</a>

读取文件内容后输出左侧加入行号的内容
* nl [options] [files]
  * -b   #与选项a, t一起使用,控制行号的输出
    a    #-b a  所有行都有行号
    t  #-b t 空行不输出行号
    n #-b n 所有行均不输出行号
  * -n  #与ln, rn, rz一起使用控制行号位置及补0的输出
    ln  #-n ln 行号在所在字段的左侧
    rn  #-n rn 行号在所在字段的右侧
    rz  #-n rz 行号在所在字段的右侧,左侧补0

[centos7@root dir]# nl /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science

 3  nameserver 192.168.17.1
   
 4  nameserver 172.18.0.1

[centos7@root dir]# nl -b a /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science
3
4 nameserver 192.168.17.1
5
6 nameserver 172.18.0.1
[centos7@root dir]# nl -b t /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science

 3  nameserver 192.168.17.1
   
 4  nameserver 172.18.0.1

[centos7@root dir]# nl -b n /etc/resolv.conf
# Generated by NetworkManager
search magedu.com zhubiao.science

   nameserver 192.168.17.1
   
   nameserver 172.18.0.1

[centos7@root dir]# nl -n ln /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science

3 nameserver 192.168.17.1

4 nameserver 172.18.0.1
[centos7@root dir]# nl -n rn /etc/resolv.conf
1 # Generated by NetworkManager
2 search magedu.com zhubiao.science

 3  nameserver 192.168.17.1
   
 4  nameserver 172.18.0.1

[centos7@root dir]# nl -n rz /etc/resolv.conf
000001 # Generated by NetworkManager
000002 search magedu.com zhubiao.science

000003 nameserver 192.168.17.1

000004 nameserver 172.18.0.1
[centos7@root dir]# nl -n rz -w2 /etc/resolv.conf
01 # Generated by NetworkManager
02 search magedu.com zhubiao.science

03 nameserver 192.168.17.1

04 nameserver 172.18.0.1


>###<a id="head">head</a>

Out put the first part of files 读取文件的前几行(默认为10行,也可指定)并输出
* head [options] [files]
  -n NUM  #输出前NUM行
  -v 行首打印所读取文件内容的完整路径名
  -c NUM #输出前NUM个字符

[centos7@root dir]# head /etc/passwd
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
operator:x:11:0:operator:/root:/sbin/nologin

行首输出文件路径名

[centos7@root dir]# head -v /etc/passwd
==> /etc/passwd <==
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
operator:x:11:0:operator:/root:/sbin/nologin

指定输出前3行

[centos7@root dir]# head -n 3 /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin

输出前4个字符

[centos7@root dir]# head -c 4 /etc/passwd
root[centos7@root dir]#


>###<a id="tail">tail</a>

Out put the last part of files
* tail [options] [fies]
-n NUM #输出文件后NUM行
-v #输出首行显示文件完整路径内容
-c NUM #输出文件最后NUM个字符

[centos7@root dir]# tail /etc/passwd
setroubleshoot:x:991:988::/var/lib/setroubleshoot:/sbin/nologin
pulse:x:171:171:PulseAudio System Daemon:/var/run/pulse:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
gnome-initial-setup:x:990:985::/run/gnome-initial-setup/:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
zb20:x:1000:1000:zb20:/home/zb20:/bin/bash
[centos7@root dir]# tail -n 3 /etc/passwd
ntp:x:38:38::/etc/ntp:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
zb20:x:1000:1000:zb20:/home/zb20:/bin/bash
[centos7@root dir]# tail -v -n 3 /etc/passwd
==> /etc/passwd <==
ntp:x:38:38::/etc/ntp:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
zb20:x:1000:1000:zb20:/home/zb20:/bin/bash

输出文件末尾9个字符

[centos7@root dir]# tail -c 9 /etc/passwd
bin/bash


>###<a id="less">less<a>

非常好用的一个浏览文件内容的工具,可以通过快捷键向前/后浏览文件内容,可以通过关键字搜索文件中的字符串。对文件的前后翻屏功能类似VIM, MAN手册的浏览就是通过less命令实现的。
 * less FILES
   * 翻屏快捷键
    Ctrl + F #向文件首部翻一屏
    Ctrl + B #向文件尾部翻一屏
    Ctrl + D #向文件首部翻半屏
    Ctrl + U #向文件尾部翻半屏
    j  #向文件尾部滚动一行
    k #向文件首部滚动一行
  * 搜索
    * / [patern]
      n #向前搜索下一个匹配的模式或字符串
      N #向后搜索上一个匹配的模式或字符串
    * ?[patern]
      n #向后搜索上一个匹配的模式或字符串
      N #向前搜索下一个匹配的模式或字符串

>###<a id="more">more</a>

more功能和less类似,但没有less功能多,比如不可以向文件首部翻屏,只能向尾部翻屏,所以建议使用less

>### <a id="hexdump">hexdump</a>

通常用来查看二进制文件,但不限于只能看二进制文件。
* hexdump [option] [files]
-o #八进制显示
-d #十进制显示
-x #十六进制显示
-C #十六进制和ASCII字符显示

 以下实例通过hexdump读取cat命令的二进制文件,因内容过多,此处使用<a href="#head">head</a> -n 3 来显示前三行内容

[centos7@root dir]# hexdump /bin/cat | head -n 3
0000000 457f 464c 0102 0001 0000 0000 0000 0000
0000010 0002 003e 0001 0000 2644 0040 0000 0000
0000020 0040 0000 0000 0000 cbc0 0000 0000 0000
[centos7@root dir]# hexdump -o /bin/cat | head -n 3
0000000 042577 043114 000402 000001 000000 000000 000000 000000
0000010 000002 000076 000001 000000 023104 000100 000000 000000
0000020 000100 000000 000000 000000 145700 000000 000000 000000
[centos7@root dir]# hexdump -d /bin/cat | head -n 3
0000000 17791 17996 00258 00001 00000 00000 00000 00000
0000010 00002 00062 00001 00000 09796 00064 00000 00000
0000020 00064 00000 00000 00000 52160 00000 00000 00000
[centos7@root dir]# hexdump -x /bin/cat | head -n 3
0000000 457f 464c 0102 0001 0000 0000 0000 0000
0000010 0002 003e 0001 0000 2644 0040 0000 0000
0000020 0040 0000 0000 0000 cbc0 0000 0000 0000
[centos7@root dir]# hexdump -C /bin/cat | head -n 3
00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 02 00 3e 00 01 00 00 00 44 26 40 00 00 00 00 00 |..>.....D&@.....|
00000020 40 00 00 00 00 00 00 00 c0 cb 00 00 00 00 00 00 |@...............|


>### <a id="od">od</a>

读取二进制文件
* od [option] [files]
-o #八进制显示
-d #十进制显示
-x #十六进制显示
以下实例通过od读取cat命令的二进制文件,因内容过多,此处使用<a href="#head">head</a> -n 2 来显示前三行内容

[centos6@root test]# od -o /bin/cat | head -n 2
0000000 042577 043114 000402 000001 000000 000000 000000 000000
0000020 000002 000076 000001 000000 014120 000100 000000 000000
[centos6@root test]# od -d /bin/cat | head -n 2
0000000 17791 17996 258 1 0 0 0 0
0000020 2 62 1 0 6224 64 0 0
[centos6@root test]# od -x /bin/cat | head -n 2
0000000 457f 464c 0102 0001 0000 0000 0000 0000
0000020 0002 003e 0001 0000 1850 0040 0000 0000


>### <a id="cp">cp</a>

* cp [options] [Source_File] [Destination_File]
  -p #same as --preserve=mode,ownership,timestamps
  -u #当原文件更新时才覆盖目标文件
  -R | r #若原文件有子目录时,连同目录一起复制
  -d #当原文件内容包含符号链接时,选项复制符号链接,不加-d选项是复制符号链接指向的原文件内容
  -a same as -dr
  -i | --interactive #prompt before overwrite 若目标文件存在普通用户复制时,提示是否覆盖,建议使用cp时加-i选项
-f | --force

-p 复制时目标文件保留原文件的属性(时间戳,属主属组,文件权限)
[centos6@zb10 ~]$ ll 1.txt
-rw-rw-r--. 1 zb10 zb10 0 Jul 15 22:25 1.txt
[centos6@root zb10]# cp 1.txt 2.txt
[centos6@root zb10]# cp -p 1.txt 3.txt
[centos6@root zb10]# ll [[:digit:]].txt
-rw-rw-r--. 1 zb10 zb10 0 Jul 15 22:25 1.txt #原文件
-rw-r--r--. 1 root root 0 Jul 15 22:25 2.txt #未加-p选项属性将变化
-rw-rw-r--. 1 zb10 zb10 0 Jul 15 22:25 3.txt #加-p选项的目标文件属性不变

-u 只有当原文件比目标文件修改时间更新才覆盖目标文件

如下file2 比file1更新,-u 选项时将file1复制到file2时不会覆盖file2, 而反之则覆盖file1的内容

[centos6@zb10 ~]$ ll file*
-rw-rw-r--. 1 zb10 zb10 15 Jul 15 22:06 file1
-rw-rw-r--. 1 zb10 zb10 15 Jul 15 22:07 file2
[centos6@zb10 ~]$ head -v file*
==> file1 <==
file1 Contents

==> file2 <==
file2 Contents
[centos6@zb10 ~]$ cp -u file1 file2
[centos6@zb10 ~]$ head -v file*
==> file1 <==
file1 Contents

==> file2 <==
file2 Contents
[centos6@zb10 ~]$ cp -u file2 file1
[centos6@zb10 ~]$ head -v file*
==> file1 <==
file2 Contents

==> file2 <==
file2 Contents

-d 当原文件内容包含符号链接时,选项复制符号链接,不加-d选项是复制符号链接指向的原文件内容

[centos6@root test]# tree
.
├── dir1
│ ├── a
│ │ └── file
│ └── file.ln -> a/file
└── dir2

3 directories, 2 files
[centos6@root test]# cp dir1/file.ln dir2/
[centos6@root test]# tree
.
├── dir1
│ ├── a
│ │ └── file
│ └── file.ln -> a/file
└── dir2
└── file.ln

3 directories, 3 files
[centos6@root test]# cp -d dir1/file.ln dir2/
cp: overwrite `dir2/file.ln'? y
[centos6@root test]# tree
.
├── dir1
│ ├── a
│ │ └── file
│ └── file.ln -> a/file
└── dir2
└── file.ln -> a/file

3 directories, 3 files


>###<a id="mv">mv</a>

Move or rename files 移动或重命名文件
* mv [options] [source] [destination] 
  -f | --force  目标文件存在时,直接覆盖
  -i | --interactive 提示用户是否覆盖目标文件
  -u | --update 只有当原文件更新时,才执行移动

如下所示当前目录下有两个目录,dir1,dir2,将dir2 移动到dir1下

[centos6@root test]# tree
.
├── dir1
└── dir2
└── a
└── file1

3 directories, 1 file
[centos6@root test]# mv dir2 dir1
[centos6@root test]# tree
.
└── dir1
└── dir2
└── a
└── file1

3 directories, 1 file
[centos6@root test]#

修改dir1目录名为dir3

[centos6@root test]# mv dir1 ./dir3
[centos6@root test]# ll
total 4
drwxr-xr-x. 3 root root 4096 Jul 16 09:41 dir3


>###<a id="rm">rm</a>

Remove files or directories 删除文件或目录(子目录)
* rm [options] [files]
  -f | --force #删除时,文件或目录不存在时不提示
  -r | -R | --recursive #删除目录及其下的子目录或文件
  -i #删除每一个文件、目录时均提示是否删除

[centos6@root test]# rm dir3/dir2/a/file1
rm: remove regular empty file `dir3/dir2/a/file1'? y
[centos6@root test]# tree
.
└── dir3
└── dir2
└── a

3 directories, 0 files
[centos6@root test]# rm -rf dir3 #彻底删除dir3及其目录下的所有子目录、文件


>###<a id="mkdir">mkdir</a>

Make Directories 创建目录

* mkdir [options] [directories]
  -p | --parents 创建多级目录时,其父目录不存在则先创建其父目录
  -m | --mode=MODE 创建目录时指定目录的权限
  -v 显示创建目录的过程

创建目录dir1

[centos6@root test]# mkdir -v dir1
mkdir: created directory `dir1'
[centos6@root test]# ll -d dir1
drwxr-xr-x. 2 root root 4096 Jul 16 10:06 dir1

-m 创建目录dir2,并指定目录权限为rw-rw-rw-(666)

[centos6@root test]# mkdir -m 666 dir2
[centos6@root test]# ll -d dir1 dir2
drwxr-xr-x. 2 root root 4096 Jul 16 10:06 dir1
drw-rw-rw-. 2 root root 4096 Jul 16 10:07 dir2

-p 创建多级目录

[centos6@root test]# mkdir -pv dir3/a/b/c
mkdir: created directory dir3' mkdir: created directorydir3/a'
mkdir: created directory dir3/a/b' mkdir: created directorydir3/a/b/c'
[centos6@root test]# ll -d dir3/a/b/c
drwxr-xr-x. 2 root root 4096 Jul 16 10:08 dir3/a/b/c


> ###<a id="rmdir">rmdir</a>

remove empty directories 删除空目录
* rmdir
  -p | --parents #Remove empty directories and its ancestors 删除其空目录及其父辈空目录

如下所示,除了file是文件,其它均为空文件夹,下面练习是使用rmdir

[centos6@root test]# tree
.
├── dir1
├── dir2
│ └── file
└── dir3
└── a
└── b

5 directories, 1 file

删除空目录dir1

[centos6@root test]# rmdir dir1
[centos6@root test]# tree
.
├── dir2
│ └── file
└── dir3
└── a
└── b
4 directories, 1 file

若不是空目录,比如文件file无法使用rmdir删除

[centos6@root test]# rmdir dir2/file
rmdir: failed to remove `dir2/file': Not a directory

-p 连同其父空目录一起删除

[centos6@root test]# rmdir dir3/a/b/ #不适用-p仅删除其自身空目录
[centos6@root test]# tree
.
├── dir2
│ └── file
└── dir3
└── a

3 directories, 1 file
[centos6@root test]# rmdir -p dir3/a/ #使用-p连同其父空目录一起删除
[centos6@root test]# tree
.
└── dir2
└── file

1 directory, 1 file


>### <a id="dd">id</a>

Copy and Convert files 复制或转换文件格式
dd 功能很强大,可以直接读取磁盘扇区的内容,在此列举一个dd的复制工具
* dd if=*input_file* of=*output_file* bs=*block_size* count=*number*
  if #Read from file instead of stdin 从文件读入(包括装置,Linux中一切皆文件喔),若无if将从标准输入(从键盘输入)
  of #Write to file instead of stdout 写入到文件,无此项将输出到屏幕
  bs #读取和写入的block大小,默认为512bytes
    * ibs #读取的block大小
    * obs #写入的block大小

  count #bs的数量

将/bin/cat文件备份到当前目录下

[centos7@root ~]# dd if=/bin/cat of=./cat.bk bs=512
105+1 records in
105+1 records out
54080 bytes (54 kB) copied, 0.000900543 s, 60.1 MB/s
[centos7@root ~]# ll -h cat.bk
-rw-r--r--. 1 root root 53K Jul 16 11:06 cat.bk


>### <a id="gedit">gedit</a>

gdit是图形终端的一个文本编辑工具,通过下图方式打开
![image.png](http://upload-images.jianshu.io/upload_images/6823414-459f37ae79f49fc5.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/500)
gedit也可以通过图形终端上的命令行接口打开`[centos6@root Desktop]# gedit
`
>### <a id="nano">nano</a>

nano #命令行下的文本编辑工具,命令行下面有更强大的文本编辑工具vim,建议使用vim

>### <a id="file">file</a>

file Determine file types |判断文件类型

查看cat命令文件类型

[centos7@root ~]# file /bin/cat
/bin/cat: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.32, BuildID[sha1]=fac04659ab9a437b5384c09f4731023373821a39, stripped

查看/etc/passwd文件类型

[centos7@root ~]# file /etc/passwd
/etc/passwd: ASCII text

查看/etc/类型

[centos7@root ~]# file /etc
/etc: directory


>###<a id="type">type</a>

type 判断命令类型
* type [*options*] *command*
  -a 显示所有包含该命令的位置
* 命令类型
  * builtin Shell内建命令
  * 外部命令,不包含在shell内建命令里的命令
  * alias | 别名
  * keword | 关键字
  * function | 函数

echo即有内建命令,也有外部命令,为了演示type,我们再给echo定义个别名

[centos6@root test]# alias echo
alias echo='echo -e'

不加任何选项,使用type查询,若有别名,只能查到别名

[centos6@root test]# type echo
echo is aliased to `echo -e'

-a 选项

[centos6@root test]# type -a echo
echo is aliased to `echo -e'
echo is a shell builtin
echo is /bin/echo

  
>### <a id="id">id</a>
Print user and group information for specified  the USERNAME or the currentuser
* id [options] [users]
  -g 用户所在有效组
  -G 用户所在的所有组

不指定user将显示当前用户的信息

[centos7@root ~]# id
uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023

指定用户

[centos7@root ~]# id user1
uid=1001(user1) gid=1003(user1) groups=1003(user1),1001(group1),1002(group2)

[centos7@root ~]# id -g user1
1003

[centos7@root ~]# id -G user1
1003 1001 1002


> ### <a id="getent">getent</a>

Get entries from name server switch 从定义的数据库里获得记录
数据库定义在/etc/nsswitch.conf 文件中
* getent database [entries]

从/etc/passwd数据库内获取包含root用户的条目

[centos7@root ~]# getent passwd root
root:x:0:0:root:/root:/bin/bash

从/etc/group 数据库内获取包含zb20的条目

[centos7@root ~]# getent group zb20
zb20:x:1000:zb20


>###<a id="iconv">iconv</a>

Convert text from one character encoding to another | 转换字符编码
* iconv -f  *from_encoding* -t *to_encoding* *input_file* -o *output_file*
  -f 原文件编码
  -t 目标文件编码
  -o 输出文件
  -l 列出iconv能转换的编码

windows系统上保存默认文本编码格式,在linux系统中无法打开,就可以通过iconv转换成linux系统识别的编码

[centos7@root ~]# cat source.txt
βo³¤³ȍ󁯿գ¬°ڊS¢ћ°ڊC
[centos7@root ~]# iconv -f gb2312 -t UTF-8 source.txt -o destination.txt
[centos7@root ~]# cat destination.txt
万里长城万里空,百世英雄百世梦


>### <a id="echo">echo</a>

打印shell变量,指定的字符串
* echo [options] [string]
-n #输出字符后末尾不换行,默认换行
-e #输出字符中的转义字符生效
 * \t #TAB
 * \n #newline

显示shell变量的值

[centos6@root test]# echo $PATH
/usr/lib64/qt-3.3/bin:/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin
[centos6@root test]# echo $PS1
[][\h@\u \W]$ []
[centos6@root test]# a=50
[centos6@root test]# echo $a
50

-n 末尾不换行

[centos6@root test]# echo "hello everyone"
hello everyone
[centos6@root test]# echo -n "hello everyone"
hello everyone[centos6@root test]#

-e 转义字符生效

[centos6@root test]# echo "hello\t welcome to QuJing\nI believe..."
hello\t welcome to QuJing\nI believe...
[centos6@root test]# echo -e "hello\t welcome to QuJing\nI believe..."
hello welcome to QuJing
I believe...

输出连续或不连续字符

[centos7@root ~]# echo {a..z}
a b c d e f g h i j k l m n o p q r s t u v w x y z
[centos7@root ~]# echo {A..z}
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z
[centos7@root ~]# echo {1..9}
1 2 3 4 5 6 7 8 9
[centos7@root ~]# echo {9..1}
9 8 7 6 5 4 3 2 1
[centos7@root ~]# echo {1..10..2}
1 3 5 7 9
[centos7@root ~]# echo {001..10..2}
001 003 005 007 009
[centos7@root ~]# echo {1,7,q,b}
1 7 q b

 
>###<a id="history">history</a>

读取历史命令记录
。。。更多功能待续

[centos7@root ~]# history | head -n 5
1 clear
2 cat /etc/gdm/custom.conf
3 vim /etc/gdm/custom.conf
4 reboot
5 shutdown -h now


>###<a id="ifconfig">ifconfig</a>

配置或显示网卡参数

显示eth1网卡参数

[centos6@root test]# ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:0C:29:E3:FB:0C
inet addr:172.18.253.214 Bcast:172.18.255.255 Mask:255.255.0.0
inet6 addr: fe80::20c:29ff:fee3:fb0c/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:440093 errors:0 dropped:0 overruns:0 frame:0
TX packets:3225 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:43780248 (41.7 MiB) TX bytes:241256 (235.6 KiB)

关闭eth1网卡

[centos6@root test]# ifconfig eth1 down
[centos6@root test]# ifconfig eth1
eth1 Link encap:Ethernet HWaddr 00:0C:29:E3:FB:0C
BROADCAST MULTICAST MTU:1500 Metric:1
RX packets:440107 errors:0 dropped:0 overruns:0 frame:0
TX packets:3227 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:43781936 (41.7 MiB) TX bytes:241410 (235.7 KiB)

启动eth1网卡

[centos6@root test]# ifconfig eth1 up


>###<a id="ping">ping</a>

测试网络是否连通
* ping [options] [ip/name]
  -c COUNT  发送ECHO_REQUEST 包的数量

[centos6@root test]# ping -c 3 192.168.17.20
PING 192.168.17.20 (192.168.17.20) 56(84) bytes of data.
64 bytes from 192.168.17.20: icmp_seq=1 ttl=64 time=3.66 ms
64 bytes from 192.168.17.20: icmp_seq=2 ttl=64 time=0.508 ms
64 bytes from 192.168.17.20: icmp_seq=3 ttl=64 time=0.848 ms

--- 192.168.17.20 ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2003ms
rtt min/avg/max/mdev = 0.508/1.673/3.664/1.414 ms


>###<a id="exit">exit</a> <a id="quit">quit</a> <a id="logout">logout</a>

quit, exit, logout 退出登录

>### <a id="init">init</a>

切换运行级别
* init NUM #NUM为:1,2,3,4,5,6
CentOS6 上在/etc/inittabe中定义了各运行级别
\# Default runlevel. The runlevels used are:
\#   0 - halt (Do NOT set initdefault to this)  关机
\#   1 - Single user mode  单用户模式
\#   2 - Multiuser, without NFS (The same as 3, if you do not have networking) 无网络多用户模式(命令行界面)
\#   3 - Full multiuser mode 多用户模式(命令行界面)
\#   4 - unused  未使用,保留
\#   5 - X11  图形界面
\#   6 - reboot (Do NOT set initdefault to this) 重启

>###<a id="runlevel">runlevel</a>

查看当前系统运行级别

可以通过runlevel 或 who -r 查看当前系统运行级别

[centos6@root test]# runlevel
[centos6@root test]# who -r
run-level 5 2017-07-15 06:26
N 5


>### <a id="shutdown">shutdown</a>

最常用的关机或重启命令
* shutdown [options] [time] [string]
-r reboot after shutdown 重启
-h 关机
-c 取消关机或重启

立即关机

shutdown -h now

过5分钟后关机

[centos6@root test]# shutdown -h 5 &
[1] 10237
[centos6@root test]#
Broadcast message from root@centos6.zhubiao.science
(/dev/pts/0) at 15:51 ...

The system is going down for halt in 5 minutes!

取消关机

[centos6@root test]# shutdown -c
shutdown: Shutdown cancelled
[1]+ Done shutdown -h 5

5分钟后重启

[centos6@root test]# shutdown -r 5

Broadcast message from root@centos6.zhubiao.science
(/dev/pts/0) at 15:53 ...

The system is going down for reboot in 5 minutes!


>###<a id="halt">halt</a> <a id="reboot">reboot</a> <a id="poweroff">pwoeroff</a> 

* reboot 重启
* halt, poweroff 关机

>###<a id="free">free</a>

显示当前内存使用情况
* free [options]
-h #human readable output 自动确定最佳单位显示内存使用量
-b, -k, -m, -g 以bytes, KB, MB, GB为单位显示内存使用量
-t 最后一行汇总RAM+SWAP内存的使用总量
-l 

[centos7@root ~]# free -h
total used free shared buff/cache available
Mem: 976M 202M 252M 13M 522M 539M
Swap: 2.0G 0B 2.0G

[centos7@root ~]# free -th
total used free shared buff/cache available
Mem: 976M 202M 251M 13M 522M 539M
Swap: 2.0G 0B 2.0G
Total: 3.0G 202M 2.2G

[centos7@root ~]# free -lh
total used free shared buff/cache available
Mem: 976M 202M 251M 13M 522M 539M
Low: 976M 724M 251M
High: 0B 0B 0B
Swap: 2.0G 0B 2.0G

也可通过查看内核进程数据来查看内存使用情况

[centos7@root ~]# cat /proc/meminfo
MemTotal: 999964 kB
MemFree: 257648 kB
MemAvailable: 551900 kB
Buffers: 1804 kB
Cached: 390520 kB
SwapCached: 0 kB
Active: 266780 kB
Inactive: 224516 kB
Active(anon): 94740 kB
Inactive(anon): 17896 kB
Active(file): 172040 kB
Inactive(file): 206620 kB
Unevictable: 0 kB
Mlocked: 0 kB
SwapTotal: 2097148 kB
SwapFree: 2097148 kB
Dirty: 0 kB
Writeback: 0 kB
AnonPages: 99036 kB
Mapped: 35392 kB
Shmem: 13664 kB
Slab: 142844 kB
SReclaimable: 86632 kB
SUnreclaim: 56212 kB
KernelStack: 4832 kB
PageTables: 7260 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 2597128 kB
Committed_AS: 634440 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 181824 kB
VmallocChunk: 34359310332 kB
HardwareCorrupted: 0 kB
AnonHugePages: 8192 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
HugePages_Surp: 0
Hugepagesize: 2048 kB
DirectMap4k: 98176 kB
DirectMap2M: 950272 kB


>###<a id="lsblk">lsblk</a>

列出块状设备大小及挂载点

[centos7@root ~]# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
├─sda1 8:1 0 1G 0 part /boot
├─sda2 8:2 0 50G 0 part /
├─sda3 8:3 0 50G 0 part /app
├─sda4 8:4 0 1K 0 part
└─sda5 8:5 0 2G 0 part [SWAP]
sr0 11:0 1 7.7G 0 rom /run/media/root/CentOS 7 x86_64
[centos7@root ~]# lsblk -d
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 200G 0 disk
sr0 11:0 1 7.7G 0 rom /run/media/root/CentOS 7 x86_64


>###<a id="lscpu">lscpu</a>

显示CPU信息

[centos7@root ~]# lscpu
Architecture: x86_64
CPU op-mode(s): 32-bit, 64-bit
Byte Order: Little Endian
CPU(s): 2
On-line CPU(s) list: 0,1
Thread(s) per core: 1
Core(s) per socket: 1
Socket(s): 2
NUMA node(s): 1
Vendor ID: GenuineIntel
CPU family: 6
Model: 58
Model name: Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
Stepping: 9
CPU MHz: 2493.686
BogoMIPS: 4988.79
Hypervisor vendor: VMware
Virtualization type: full
L1d cache: 32K
L1i cache: 32K
L2 cache: 256K
L3 cache: 3072K
NUMA node0 CPU(s): 0,1

通过内核进程文件/proc/cpuinfo查看cpu信息

[centos7@root ~]# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 58
model name : Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
stepping : 9
microcode : 0x12
cpu MHz : 2493.686
cache size : 3072 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 dts mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm ida arat epb pln pts dtherm fsgsbase tsc_adjust smep
bogomips : 4988.79
clflush size : 64
cache_alignment : 64
address sizes : 42 bits physical, 48 bits virtual
power management:

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 58
model name : Intel(R) Core(TM) i5-3210M CPU @ 2.50GHz
stepping : 9
microcode : 0x12
cpu MHz : 2493.686
cache size : 3072 KB
physical id : 2
siblings : 1
core id : 0
cpu cores : 1
apicid : 2
initial apicid : 2
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 dts mmx fxsr sse sse2 ss syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts nopl xtopology tsc_reliable nonstop_tsc aperfmperf pni pclmulqdq ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx f16c rdrand hypervisor lahf_lm ida arat epb pln pts dtherm fsgsbase tsc_adjust smep
bogomips : 4988.79
clflush size : 64
cache_alignment : 64
address sizes : 42 bits physical, 48 bits virtual
power management:


>###<a id=".">.</a>  <a id="source">source</a>

执行shell脚本

在 /etc/profile.d/env.sh中设置命令提示符,然后使用. DIR或soruce DIR执行脚本,后命令提示符将生效

[~] cat /etc/profile.d/env.sh
export PS1="[\h@\u \W]\$ "

[~] . /etc/profile.d/env.sh
[centos6@root ~]#


>###<a id="enable">enable</a>

Enable and disable shell builtins | 启用或停用SHELL内建命令

* enable [options] [command]
  -a 列出所有内建命令,不管是否被禁用
  -n *command* 停用命令*command*

停用cd命令

[centos6@root ~]# enable -n cd
[centos6@root ~]# cd
-bash: cd: command not found

[centos6@root ~]# enable -a | grep cd
enable -n cd

启用cd命令

[centos6@root ~]# enable cd
[centos6@root ~]# cd ..
[centos6@root /]# cd -
/root


>###<a id="hash">hash</a>

缓存已执行的外部命令的路径,以便下次使用节省搜索命令的时间

* hash [options] [command]
  -d command 从hash缓存中删除command命令记录
  -r 清空hash 缓存
  -l 列出路径及命令名
  -p name #在hash缓存中给路径起别名

查看已缓存的外部命令

[centos6@root ~]# hash
hits command
1 /sbin/ifconfig
1 /usr/bin/man
1 /bin/ls
8 /usr/bin/clear

列出缓存的路径及其命令名

[centos6@root ~]# hash -l
builtin hash -p /sbin/ifconfig ifconfig
builtin hash -p /usr/bin/man man
builtin hash -p /bin/ls ls
builtin hash -p /usr/bin/clear clear

从hash缓存中删除命令man

[centos6@root ~]# hash -d man
[centos6@root ~]# hash -l
builtin hash -p /sbin/ifconfig ifconfig
builtin hash -p /bin/ls ls
builtin hash -p /usr/bin/clear clear

起别名

[centos6@root ~]# hash -p /sbin/ifconfig ifcon
[centos6@root ~]# hash -l
builtin hash -p /sbin/ifconfig ifconfig
builtin hash -p /sbin/ifconfig ifcon
builtin hash -p /bin/ls ls
builtin hash -p /usr/bin/clear clear
[centos6@root ~]# ifcon eth0
eth0 Link encap:Ethernet HWaddr 00:0C:29:E3:FB:02
inet addr:192.168.17.10 Bcast:192.168.17.255 Mask:255.255.255.0
inet6 addr: fe80::20c:29ff:fee3:fb02/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:21356 errors:0 dropped:0 overruns:0 frame:0
TX packets:18035 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:1995596 (1.9 MiB) TX bytes:3239265 (3.0 MiB)

清空hash缓存

[centos6@root ~]# hash -r
[centos6@root ~]# hash
hash: hash table empty


>###<a id="alias">alias</a> <a id="unalis">unalis</a>

* alias #Define or display aliases 定义别名
  alias name="value"
* unalias 取消别名
  unalias name

查看以定义的别名

[centos6@root ~]# alias
alias cp='cp -i'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

定义别名

[centos6@root ~]# alias grep="grep --color"
[centos6@root ~]# alias
alias cp='cp -i'
alias grep='grep --color'
alias l.='ls -d .* --color=auto'
alias ll='ls -l --color=auto'
alias ls='ls --color=auto'
alias mv='mv -i'
alias rm='rm -i'
alias which='alias | /usr/bin/which --tty-only --read-alias --show-dot --show-tilde'

在配置文件/etc/bashrc中定义别名,所有用户均生效

[centos6@root ~]# vim /etc/bashrc
[centos6@root ~]# tail -n 3 /etc/bashrc

Define alias

alias grep="grep --color"
[centos6@root ~]# . /etc/bashrc

在自己家目录配置文件~/.basrc中定义,只有当前用户生效

[centos6@root ~]# vim ~/.bashrc
[centos6@root ~]# cat ~/.bashrc

.bashrc

User specific aliases and functions

alias rm='rm -i'
alias cp='cp -i'
alias mv='mv -i'


>###<a id="date">date</a>

Print or set system date or time 显示或设置系统时间

* date [option] [+format]
设定时间的两种方法
 * date [MMDDhhmm[[CC]YY][.ss]]
 * date -s "*string*"

  -d "*string*"
    * string: 
      "1 year"
      "1 year ago"
      "3 years"
      "3 years ago"
      "1 day"
      "1 day ago"
      "3 days"
      "3 days ago"

  * format
    %Y year
    %m month
    %d day
    %H hour
    %M minute
    %S second
    %F fulldate same as %Y-%m-%d
    %T time,same as %H:%M:%S

以不同的格式显示时间

[centos6@root ~]# date +%F
2017-07-17
[centos6@root ~]# date +%T
22:57:11
[centos6@root ~]# date "+%F %T"
2017-07-17 22:57:19
[centos6@root ~]# date +"%F %T"
2017-07-17 22:57:27
[centos6@root ~]# date "+%Y-%m-%d %H:%M:%S"
2017-07-17 22:57:55

设定时间 [MMDDhhmm[[CC]YY][.ss]]

[centos6@root ~]# date 062012121990.33
Wed Jun 20 12:12:33 CDT 1990
[centos6@root ~]# date +"%F %T"
1990-06-20 12:12:48

设定时间 date -s STRING

[centos6@root ~]# date -s "20170717 23:03:10"
Mon Jul 17 23:03:10 CST 2017
[centos6@root ~]# date +"%F %T"
2017-07-17 23:03:22

当前时间

[centos6@root ~]# date +"%F %T"
2017-07-17 23:09:11

显示4年前的日期

[centos6@root ~]# date -d "4 years ago" +"%F %T"
2013-07-17 23:09:32

显示10天前的日期

[centos6@root ~]# date -d "10 days ago" +"%F %T"
2017-07-07 23:09:52

显示10天后的日期

[centos6@root ~]# date -d "10 days" +"%F %T"
2017-07-27 23:10:01


>###<a id=clock>clock</a> <a id="hwclock">hwclock</a>

hwclock,clock功能相同,都是设定硬件时间
* hwclock [options] 
  * hwclock --set --date="*string*" #按字符串描述的时间设定硬件时间
  * hwclock --systohc #将系统时间更新到硬件时间
  * hwclock --hctosys #将硬件时间更新到系统时间

clock其实是hwclock的符号链接

[centos6@root ~]# ll /sbin/clock
lrwxrwxrwx. 1 root root 7 Jul 15 01:17 /sbin/clock -> hwclock

[centos7@root ~]# hwclock
Mon 17 Jul 2017 11:20:50 PM CST -0.663348 seconds

设定硬件时间

[centos7@root ~]# hwclock --set --date="1990-06-20 10:10:10"
[centos7@root ~]# hwclock ; date
Wed 20 Jun 1990 10:10:24 AM CDT -0.100626 seconds
Mon Jul 17 23:21:39 CST 2017

[centos7@root ~]# hwclock --systohc
[centos7@root ~]# hwclock ; date
Mon 17 Jul 2017 11:22:01 PM CST -0.944138 seconds
Mon Jul 17 23:22:00 CST 2017
[centos7@root ~]# date -s "19900620" +%F
1990-06-20

[centos7@root ~]# hwclock --hctosys
[centos7@root ~]# hwclock ; date
Mon 17 Jul 2017 11:22:58 PM CST -0.411873 seconds
Mon Jul 17 23:22:57 CST 2017


>###<a id="cal">cal</a>

Display a calendar | 显示日历 
* cal [options] [[[day], month], year]
  -1  显示一个月
  -3 display prev/current/next month

[centos6@root ~]# cal
July 2017
Su Mo Tu We Th Fr Sa
1
2 3 4 5 6 7 8
9 10 11 12 13 14 15
16 17 18 19 20 21 22
23 24 25 26 27 28 29
30 31
[centos6@root ~]# cal 20 06 1990
June 1990
Su Mo Tu We Th Fr Sa
1 2
3 4 5 6 7 8 9
10 11 12 13 14 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30


>###<a id="history">history</a>

Display or manipulate the history list | 显示或操作命令历史
  从登录开始所操作的命令历史若没有人为追加至命令历史文件中,则存在于内存中,当用户退出登录时自动追加至命令历史文件中
命令历史文件~/.bash_history, m
* 命令历史大小,显示受以下变量控制
  这些变量要永久生效需将其写入配置文件中/etc/profile,~/.bash_profile
  * HISTFILE   #定义了命令历史文件的位置
  * HISTSIZE  #定义内存中命令历史记录的最大数量
  * HISTFILESIZE  #定义命令历史文件中存放记录的最大数量
  * HISTCONTROL
    * ignoredups  #连续重复的命令只记录一条
    * ignorespace  #命令执行前有空白的,不记录
    * ignoreboth  #上面两条同时生效
  * HISTTIMEFORMAT ="%F %T"  定义命令历史记录中显示的时间格式
  * HISTIGNORE="str*" #以str开头的命令不记录
  

* history [options] [name]
  -c 清空当前内存中的命令历史
  -d *NAME* 从内存中删除某条命令历史记录
  -a 将内存中未从文件中读取,新产生的命令历史记录追加至文件中
  -w 将当前内存中的命令历史覆盖命令历史文件
  -p 不将当前执行的扩展命令记录至命令历史中

默认HISTSIZE为1000,在/etc/profile中定义了其大小

[centos6@root ~]# echo $HISTSIZE
1000
[centos6@root ~]# cat /etc/profile | grep HISTSIZE
HISTSIZE=1000
export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL

[centos6@root ~]# echo $HISTFILESIZE
1000

[centos6@root ~]# history | tail -n 10
445 help history
446 clear
447 history
448 history -d clear
449 history -d 440
450 clear
451 pwd
452 ifconfig
453 hostname
454 history | tail -n 10

[centos6@root ~]# history -d 450
[centos6@root ~]# history | tail -n 10
446 clear
447 history
448 history -d clear
449 history -d 440
450 pwd
451 ifconfig
452 hostname
453 history | tail -n 10
454 history -d 450
455 history | tail -n 10

[centos6@root ~]# history -c
[centos6@root ~]# history
1 history

[centos6@root ~]# cat ~/.bash
.bash_history .bash_logout .bash_profile .bashrc
[centos6@root ~]# cat ~/.bash_history
history -r
。。。
[centos6@root ~]# cat ~/.bash_history | wc -l
356

-a 追加

[centos6@root ~]# history -a
[centos6@root ~]# cat ~/.bash_history | wc -l
363
[centos6@root ~]# clear
[centos6@root ~]# history -c
[centos6@root ~]# history
1 history

-w 覆盖

[centos6@root ~]# history -w
[centos6@root ~]# cat ~/.bash_history | wc -l
2


>###<a id="rz">rz</a> <a id="">sz</a> 

rz, sz 是在安装了lrzsz程序包后产生的两个工具,用于与windows系统互传文件
* rz #从widows系统上选择需上传至linux的文件
* sz FILE #将FILE从Liux中下载至windows系统


>###<a id="ldd">ldd</a>

Print shared library dependencies | 显示命令所依赖的共享库
* ldd command

[centos6@root ~]# ldd /bin/ls
linux-vdso.so.1 => (0x00007fffccfa2000)
libselinux.so.1 => /lib64/libselinux.so.1 (0x00000030d2e00000)
librt.so.1 => /lib64/librt.so.1 (0x00000030d1e00000)
libcap.so.2 => /lib64/libcap.so.2 (0x00000030d8200000)
libacl.so.1 => /lib64/libacl.so.1 (0x00000030dc600000)
libc.so.6 => /lib64/libc.so.6 (0x00000030d1600000)
libdl.so.2 => /lib64/libdl.so.2 (0x00000030d1200000)
/lib64/ld-linux-x86-64.so.2 (0x00000030d0e00000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00000030d1a00000)
libattr.so.1 => /lib64/libattr.so.1 (0x00000030dbe00000)

[centos6@root ~]# ldd /bin/cat
linux-vdso.so.1 => (0x00007ffe611f0000)
libc.so.6 => /lib64/libc.so.6 (0x00000030d1600000)
/lib64/ld-linux-x86-64.so.2 (0x00000030d0e00000)



>###<a id="uname">uname</a>

Print system information | 显示系统版本信息
* uname [option]
  -a 显示所有
  -r 内核版本
* 查看发现版本号可通过查看以下两个文件
  /etc/redhat-release
  /etc/centos-release

[centos6@root ~]# uname
Linux

[centos6@root ~]# uname -a
Linux centos6.zhubiao.science 2.6.32-696.el6.x86_64 #1 SMP Tue Mar 21 19:29:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

[centos6@root ~]# cat /etc/redhat-release
CentOS release 6.9 (Final)

[centos6@root ~]# cat /etc/centos-release
CentOS release 6.9 (Final)


>###<a id="timedatectl">timedatectl</a>

Control the system time and date 显示、设定时间(centos7)
* timedatectl [options]
  set-time *string* 设定时间
  set-ntp *bool* 是否启用ntp同步时间
  list-timezones #列出所有时区
  set-timezone #设定时区

对于centos7系统,修改时区其实是修改了/etc/localtime的符号链接指向,centos6也可以通过直接修改链接指向达到修改时区的目的

以下为CentOS7上的操作
设定时间
[centos7@root ~]# timedatectl set-time "2017-07-18 15:35:00"

查看当前时区设置为上海

[centos7@root ~]# ll /etc/localtime
lrwxrwxrwx. 1 root root 35 Jul 17 20:01 /etc/localtime -> ../usr/share/zoneinfo/Asia/Shanghai

[centos7@root ~]# timedatectl list-timezones | grep New_York
America/New_York

设定时区为New_York

[centos7@root ~]# timedatectl set-timezone America/New_York
[centos7@root ~]# date
Mon Jul 17 21:12:38 EDT 2017
[centos7@root ~]# ll /etc/localtime
lrwxrwxrwx. 1 root root 38 Jul 17 21:12 /etc/localtime -> ../usr/share/zoneinfo/America/New_York

对于CentOS6系统直接建立符号链接指向相应的时区即可,操作前备份原文件

[centos6@root ~]# ll /usr/share/zoneinfo/America/New_York
-rw-r--r--. 3 root root 3519 Dec 1 2016 /usr/share/zoneinfo/America/New_York
[centos6@root ~]# ln -s /usr/share/zoneinfo/America/New_York /etc/localtime


>###<a id="screen">screen</a>

要求同一个用户,同一台主机
screen非常有用的一个工具,可以实现多人在同一个会话中操作Linux,实现字符界面的共享,当你由于各种原因导致退出会话,会话中所运行的程序并不会结束,仍然继续运行
* screen [options]
  -S *name* #创建名为name的会话
  -x *name* #加入name会话
  ctrl+a, d #脱离会话
  -r #恢复会话
  exit 结束会话
  -ls 列出会话

创建会话

[centos6@root ~]# screen -S zb10

列出现发起的会话

[centos6@root ~]# screen -ls
There is a screen on:
50753.zb10 (Attached)
1 Socket in /var/run/screen/S-root.

加入会话

screen -x zb10

脱离会话

同时按下ctrl+a, 再按d

再加入刚脱离的会话

[centos6@root ~]# screen -r

退出会话

[centos6@root ~]# exit

![2017-07-18_095843.png](http://upload-images.jianshu.io/upload_images/6823414-ba7c81f60e9ad044.png?imageMogr2/auto-orient/strip%7CimageView2/2/w/800)


>###<a id="chvt">chvt</a>

虚拟终端之间互相切换,或图形终端上开启的伪终端与虚拟终端之间的切换
* chvt NUM #NUM终端号1-6

[centos6@root ~]# chvt 1


>###<a id="script">script</a> <a id="scriptreplay">scriptreplay</a>

* script 
  make typescript of terminal session | 录屏(字符界面)
  -o script_file 将录制的内容存放于文件中
  -t 时间通过标准错误输出到屏幕,可通过重定向到到文件中2>time_file
  exit 退出录屏
* scriptreplay  回放
  scriptreplay time_file script_file
  playback typescripts, using time information

开始录屏

[centos6@root ~]# script -a script_file -t 2>time_file
Script started, file is script_file
[centos6@root ~]# pwd
/root
[centos6@root ~]# ls
1.log a Desktop install.log.syslog Pictures test
1.txt anaconda-ks.cfg Documents localtime Public time_file
2.txt a.tar Downloads man.1 script_file typescript
3.txt core.3283 install.log Music Templates Videos
[centos6@root ~]# exit #退出录屏
exit
Script done, file is script_file

回放,下面除了第一条回放操作命令以外,其它的操作均是回放

[centos6@root ~]# scriptreplay time_file script_file
[centos6@root ~]# pwd
/root
[centos6@root ~]# ls
1.log a Desktop install.log.syslog Pictures test
1.txt anaconda-ks.cfg Documents localtime Public time_file
2.txt a.tar Downloads man.1 script_file typescript
3.txt core.3283 install.log Music Templates Videos
[centos6@root ~]# exit[centos6@root ~]#


>###<a id="man">man</a>
查看外部命令的帮助文档

* man *command*
* man 手册配置文件位置
  centos6 /etc/man.config
  centos7 /etc/man_db.conf


>###<a id=""></a>

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