2.4Linux文件系統初步

1、目錄管理：
        cd, pwd, ls  都是來查看目錄的

        mkdir: make directory  建立目錄
            -p: 當指定的目標目錄的父目錄不存在時，則先建立之
            -p, --parents
              no error if existing, make parent directories as needed
      -v, --verbose
              print a message for each created directory  打印建立每一個目錄的信息
[root@linux_basic tmp]# mkdir hello
[root@linux_basic tmp]# ls
hello
[root@linux_basic tmp]# ls hello/
[root@linux_basic tmp]# mkdir how are
[root@linux_basic tmp]# ls
are  hello  how
        rmdir: remove directory
        rmdir - remove empty directories  刪除空目錄
            -p: 刪除單傳目錄路徑中各空目錄
            -p, --parents
              remove DIRECTORY and its ancestors; e.g., ‘rmdir -p a/b/c’ is similar to ‘rmdir a/b/c a/b a’
[root@linux_basic tmp]# ls
are  hello  how
[root@linux_basic tmp]# rmdir are
[root@linux_basic tmp]# ls
hello  how
[root@linux_basic tmp]# rmdir how
[root@linux_basic tmp]# ls
hello
[root@linux_basic tmp]# mkdir -pv test/apache/you
mkdir: created directory `test'
mkdir: created directory `test/apache'
mkdir: created directory `test/apache/you'
[root@linux_basic tmp]# ls
hello  test  you
[root@linux_basic tmp]# ls test/
apache
[root@linux_basic tmp]# rmdir test/apache -p
[root@linux_basic tmp]# ls
hello  you

        bash的工做特色：沒有返回信息一般最好的信息
            每一個命令執行結束後，會有一個「執行狀態返回值」，有效範圍0-255
                0: 表示執行成功
                1-255: 表示執行失敗

            使用特殊變量$?能夠獲取最近一條命令的狀態返回值
                # echo $?
[root@linux_basic tmp]# ls
hello
[root@linux_basic tmp]# echo $?  查看上一條命令的狀態返回值
0
[root@linux_basic tmp]# ls
hello
[root@linux_basic tmp]# rmdir are 目錄不存在，刪除報錯
rmdir: failed to remove `are': No such file or directory
[root@linux_basic tmp]# echo $?
1   轉態返回值不爲0

[root@linux_basic tmp]# ls
hello
[root@linux_basic tmp]# mkdir you/are
mkdir: cannot create directory `you/are': No such file or directory
[root@linux_basic tmp]# mkdir -p you/are  建立兩層的目錄
[root@linux_basic tmp]# ls
hello  you
[root@linux_basic tmp]# ls you/
are

        bash特性之一：命令行展開
            ~: 用戶家目錄
            ~USERNAME: 指定用戶的家目錄
[root@linux_basic tmp]# echo ~
/root
[root@linux_basic tmp]# ls /home/
cactiuser
[root@linux_basic tmp]# echo ~cactiuser
/home/cactiuser
            {}: 有多個的話，每一個都會展開到對應項
                /tmp/{x,y}
                    /tmp/x, /tmp/y

                /tmp/{x,y}/z
                    /tmp/x/z, /tmp/y/z

            建立/tmp/x/z, /tmp/y/z, /tmp/x/m, /tmp/y/m
mkdir /tmp/{x,y}/{z,m}
            練習1：建立/tmp/
                a_b, c_b, a_d, c_d
[root@linux_basic tmp]# mkdir -pv {a,c}_{b,d}
mkdir: created directory `a_b'
mkdir: created directory `a_d'
mkdir: created directory `c_b'
mkdir: created directory `c_d'               

            練習2：建立/tmp/mylinux/
                boot
                    grub
                bin
                sbin
                etc
                    rc.d
                        init.d
                    sysconfig
                        network-scripts
                lib
                    modules
                lib64
                usr
                    local
                        bin
                        sbin
                        lib
                        lib64
                    bin
                    sbin
                    lib
                    lib64
                proc
                sys
                dev
                var
                    log
                    run
                    lock
                tmp

    # mkdir -pv /tmp/mylinux/{boot/grub,bin,sbin,etc/{rc.d/init.d,sysconfig/network-scripts},lib/modules,lib64,usr/{bin,sbin,lib,lib64,local/{bin,sbin,lib,lib64}},proc,sys,dev,var/{log,run,lock},tmp}
用tree能夠查看目錄的結構，安裝tree，yum install tree -y  ;此時是須要有網絡的
       
2、文件查看和文件屬性信息
    ls命令：
        list簡寫
NAME
       ls - list directory contents

SYNOPSIS
       ls [OPTION]... [FILE]...
        ls [option] [file]

            經常使用選項：
                -l: long，長格式顯示文件的詳細屬性信息
                    drwxr-xr-x.  2 root root  4096 Feb 12 09:55 account
                        左起第一位：文件類型
                        後面的9位：權限，常稱爲mode
                            r: 可讀，Read
                            w: 可寫, Write
                            x：可執行, eXcute
                        .: 表示文件有隱藏屬性
                            lsattr命令能夠查看隱藏屬性
                        數字：此文件被硬連接的次數，目錄通常都是2
                        屬主：owner, 文件的擁有者
                        屬組：group, 文件所屬的組
                        4096: 文件大小，單位是字節
                            -h: human-readable，自動作單位換算，打印大小
                            -h, --human-readable
              with -l, print sizes in human readable format (e.g., 1K 234M 2G)
[root@linux_basic tmp]# ls -lh /tmp/
total 8.0K
drwxr-xr-x. 2 root root 4.0K Dec 20 14:01 hello
drwxr-xr-x. 3 root root 4.0K Dec 20 14:08 you
                        文件最近一次被修改的時間      文件名
                -a: 顯示全部文件
                -a, --all
              do not ignore entries starting with .
[root@linux_basic tmp]# ls -a
.  ..  hello  .ICE-unix  you
                -d: 一般和-l一塊兒使用，用於僅顯示目錄自身屬性
                -d, --directory
              list directory entries instead of contents, and do not dereference symbolic links
[root@linux_basic tmp]# ls -ld /tmp
drwxrwxrwt. 5 root root 4096 Dec 20 14:40 /tmp
                -r: reverse, 逆序顯示  默認是升序顯示的
[root@linux_basic tmp]# ls
hello  you
[root@linux_basic tmp]# ls -r
you  hello               
                -R: recursive, 遞歸顯示，顯示子目錄中的內容
[root@linux_basic tmp]# ls -R
.:
hello  you

./hello:

./you:
are

./you/are:               

    文件管理類的命令：
        查看：cat, tac, head, tail, less, more
        時間戳管理：touch
        複製：cp
        移動：mv
        查看元數據屬性：stat
        文本編輯器：nano, vi

    stat: 顯示文件的元數據
        時間戳：每一個文件都有三個時間戳
            atime   訪問時間 最近一次被訪問的時間
            mtime   修改時間 最近一次被修改的時間  文件內容的改變
            ctime   改變時間 最近一次改變的時間    文件元數據的改變
[root@linux_basic tmp]# stat hello/
  File: `hello/'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: fd00h/64768d    Inode: 524365    Links: 2 被硬鏈接的次數
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 14:01:23.980000639 +0800 最近一次被訪問的時間
Modify: 2014-12-20 14:01:19.755999191 +0800 最近一次被修改的時間  文件內容的改變
Change: 2014-12-20 14:01:19.755999191 +0800 最近一次改變的時間    文件元數據的改變
inode（索引節點號，每一個文件都有索引節點，也叫元數據條目的編號） 
[root@linux_basic tmp]# stat you/   注意時間戳的改變
  File: `you/'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: fd00h/64768d    Inode: 524384      Links: 3
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 14:08:57.103000297 +0800
Modify: 2014-12-20 14:08:52.309009173 +0800
Change: 2014-12-20 14:08:52.309009173 +0800
[root@linux_basic tmp]# touch you/
[root@linux_basic tmp]# stat you/
  File: `you/'
  Size: 4096            Blocks: 8          IO Block: 4096   directory
Device: fd00h/64768d    Inode: 524384      Links: 3
Access: (0755/drwxr-xr-x)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 14:55:18.363998749 +0800
Modify: 2014-12-20 14:55:18.363998749 +0800
Change: 2014-12-20 14:55:18.363998749 +0800
   
    touch：改變文件的atime和mtime
        NAME
       touch - change file timestamps

    SYNOPSIS
       touch [OPTION]... FILE...
        DESCRIPTION
                 Update the access and modification times of each FILE to the current time.
            若是FILE不存在，默認會建立一個空文件

            -a: 僅改變atime
            -a     change only the access time
            -m: 僅改變mtime
            -m     change only the modification time
            -c: 不建立空文件
            -c, --no-create
              do not create any files
            -t [[CC]YY]MMDDhhmm[.ss]  指定那個時間修改和改變的  
            -t STAMP
              use [[CC]YY]MMDDhhmm[.ss] instead of current time
[root@linux_basic tmp]# stat test.txt
  File: `test.txt'
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: fd00h/64768d    Inode: 524405      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 14:57:35.737999993 +0800
Modify: 2014-12-20 14:57:35.737999993 +0800
Change: 2014-12-20 14:57:35.737999993 +0800
[root@linux_basic tmp]# date
Sat Dec 20 15:15:42 CST 2014
[root@linux_basic tmp]# touch -a test.txt
[root@linux_basic tmp]# stat test.txt
  File: `test.txt'
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: fd00h/64768d    Inode: 524405      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 15:15:56.177992895 +0800
Modify: 2014-12-20 14:57:35.737999993 +0800
Change: 2014-12-20 15:15:56.177992895 +0800
[root@linux_basic tmp]# touch -m test.txt
[root@linux_basic tmp]# stat test.txt
  File: `test.txt'
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: fd00h/64768d    Inode: 524405      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2014-12-20 15:15:56.177992895 +0800
Modify: 2014-12-20 15:16:53.171995492 +0800
Change: 2014-12-20 15:16:53.171995492 +0800
[root@linux_basic tmp]# touch -a -t 201211091251.36 test.txt  
[root@linux_basic tmp]# stat test.txt
  File: `test.txt'
  Size: 0               Blocks: 0          IO Block: 4096   regular empty file
Device: fd00h/64768d    Inode: 524405      Links: 1
Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    root)
Access: 2012-11-09 12:51:36.000000000 +0800
Modify: 2014-12-20 15:20:31.025993115 +0800
Change: 2014-12-20 15:22:44.780992659 +0800
             
文件查看類命令：
        cat: 鏈接並顯示文本文件內容
NAME
       cat - concatenate files and print on the standard output  鏈接文件和打印到標準輸出

SYNOPSIS
       cat [OPTION]... [FILE]...

DESCRIPTION
       Concatenate FILE(s), or standard input, to standard output.
        數據流：stream

            -E：顯示行結束符
            -E, --show-ends
            display $ at end of each line
            -n: 顯示行號
            -n, --number
              number all output lines
[root@linux_basic tmp]# cat /etc/issue
CentOS release 6.6 (Final)
Kernel \r on an \m

[root@linux_basic tmp]# cat /etc/issue -n
     1  CentOS release 6.6 (Final)
     2  Kernel \r on an \m
     3
[root@linux_basic tmp]# cat /etc/issue -E
CentOS release 6.6 (Final)$
Kernel \r on an \m$
$
Linux的換行符是$，windows下的換行符是$和回車符

        tac: 逆序顯示文件內容

            Shift+PageUp/PageDown： 翻屏，在虛擬終端上翻屏

        分屏顯示：
            more 和 less
            more到文件尾部時，會自動退出
            less到文件尾部時，不會自動退出，用q退出，和man的選項類似

        查看首部或尾部的部份內容：
            head  默認顯示頭10行
NAME
       head - output the first part of files

SYNOPSIS
       head [OPTION]... [FILE]...
            
            tail  默認顯示尾部10行
                -n #: 指定的行數，head和tail都支持此選項
[root@linux_basic tmp]# tail -5 /etc/inittab
#   5 - X11
#   6 - reboot (Do NOT set initdefault to this)
#
id:3:initdefault:
S0:12345:respawn:/sbin/agetty ttyS0 115200

            tail -f             -f, --follow[={name|descriptor}]               output appended data as the file grows; -f, --follow, and --follow=descriptor are equivalent 監控一個尾部不斷變化的文件