怎樣使用tar命令打包(備份)文件?

A:The syntax of tar is:

tar [options][files]

The options used most often with tar are as follows:

c Creates a new backup,overwriting any files already on the backup destination.

x Extracts files from backup media.

t Lists the contents of backup media.

v Displays the name of each file being processed.

f Creates backups on a specified device.

u Adds files to the backup if they are not already there,or if they have been modified since they were last written on the backup.

步驟：

1)估算打包文件的大小，確定使用檔案媒體(archive media)的空間，用命令du -s

例如：

$ lf

a.out* fork.c mbox time.c

atoi.c int.c memcpy.c vi

$ du -s

296 .

$

該例顯示的296代表the total number of 512-byte blocks,計算：512*296/1024=148kilobytes.

2)制作備份，用命令tar cvf /dev/fd0135ds18 .(將該目錄下的所有內容備份到1.44英寸軟盤中where c causes a new backup to be created,v causes each file to be displayed as the backing up takes place,and f causes the subsequent argument--/dev/fd0135ds18 to be the destination of the backup.)

注：平時硬盤上的備份，我們一般用命令tar cvf filename.tar .

例如：

$ tar cvf wuyd.tar .

a ./.profile 2 tape blocks

a ./.lastlogin 0 tape blocks

a ./mbox 10 tape blocks

a ./fork.c 2 tape blocks

a ./memcpy.c 1 tape blocks

a ./.sh_history 3 tape blocks

a ./a.out 91 tape blocks

a ./time.c 1 tape blocks

a ./vi 169 tape blocks

a ./int.c 1 tape blocks

a ./atoi.c 1 tape blocks

tar: same as archive file: ./wuyd.tar

a ./.scoadmin.pref 1 tape blocks

$ lf

a.out* fork.c mbox time.c wuyd.tar

atoi.c int.c memcpy.c vi

我們還可以用命令tar cvf /dev/fd0135ds18 ./filename將該目錄下的名為filename的文件備份到archive media中

怎樣列出tar文檔的內容?

A:tar tvf /dev/fd0135ds18

tar tvf filename.tar

例如：

$ tar tvf wuyd.tar

tar: blocksize = 20

rw-------203/50 896 Sep 17 15:07 2003 ./.profile

r--------203/21 0 Sep 24 19:49 2003 ./.lastlogin

rw-------203/50 4720 Sep 21 11:17 2003 ./mbox

rw-r--r--203/50 583 Sep 17 15:27 2003 ./fork.c

rw-r--r--203/50 218 Sep 17 20:22 2003 ./memcpy.c

rw-------203/50 1474 Sep 24 20:26 2003 ./.sh_history

rwxr-xr-x203/50 46224 Sep 22 21:00 2003 ./a.out

rw-r--r--203/50 341 Sep 19 09:02 2003 ./time.c

rw-r--r--203/50 86283 Sep 21 09:14 2003 ./vi

rw-r--r--203/50 93 Sep 21 10:53 2003 ./int.c

rw-r--r--203/50 144 Sep 22 21:00 2003 ./atoi.c

rw-r--r-- 0/3 41 Sep 23 20:34 2003 ./.scoadmin.pref

$

怎樣從tar文檔中導出文件?

A:tar xvf /dev/fd0135ds18

tar xvf filename.tar

例如：

$ mkdir uu;cp wuyd.tar ./uu

$ lf

a.out* fork.c mbox time.c vi

atoi.c int.c memcpy.c uu/ wuyd.tar

$ cd uu

$ tar xvf wuyd.tar

tar: blocksize = 20

x ./.profile, 896 bytes, 2 tape blocks

x ./.lastlogin, 0 bytes, 0 tape blocks

x ./mbox, 4720 bytes, 10 tape blocks

x ./fork.c, 583 bytes, 2 tape blocks

x ./memcpy.c, 218 bytes, 1 tape blocks

x ./.sh_history, 1474 bytes, 3 tape blocks

x ./a.out, 46224 bytes, 91 tape blocks

x ./time.c, 341 bytes, 1 tape blocks

x ./vi, 86283 bytes, 169 tape blocks

x ./int.c, 93 bytes, 1 tape blocks

x ./atoi.c, 144 bytes, 1 tape blocks

x ./.scoadmin.pref, 41 bytes, 1 tape blocks

$

我們可用命令tar xvf /dev/fd0135ds18 ./filename導出archive media中的單個文件

例如：

$ lf

wuyd.tar

$ tar xvf wuyd.tar ./time.c

tar: blocksize = 20

x ./time.c, 341 bytes, 1 tape blocks

$ lf

time.c wuyd.tar

$

怎樣使用tar命令提供的簡寫形式?

A:

$ more /etc/default/tar

# @(#) def135.src 25.2 94/07/25

#

# Copyright (C) 1987-1994 The Santa Cruz Operation, Inc.

# All Rights Reserved.

# The information in this file is provided for the exclusive use of

# the licensees of The Santa Cruz Operation, Inc. Such users have the

# right to use, modify, and incorporate this code into other products

# for purposes authorized by the license agreement provided they include

# this notice and the associated copyright notice with any such product.

# The information in this file is provided "AS IS" without warranty.

#

# default/tar - archive devices: tar(C)

#

# device block size tape

#

archive0=/dev/rfd048ds9 18 360 n

archive1=/dev/rfd148ds9 18 360 n

archive2=/dev/rfd096ds15 10 1200 n

archive3=/dev/rfd196ds15 10 1200 n

# archive4=/dev/rfd096ds9 18 720 n

archive4=/dev/rfd0135ds9 18 720 n

archive5=/dev/rfd1135ds9 18 720 n

# archive5=/dev/rfd196ds9 18 720 n

archive6=/dev/rfd0135ds18 18 1440 n

archive7=/dev/rfd1135ds18 18 1440 n

archive8=/dev/rct0 20 0 y

archive9=/dev/rctmini 20 0 y

archive10=/dev/rdsk/fp03d 18 720 n

archive11=/dev/rdsk/fp03h 18 1440 n

archive12=/dev/rdsk/fp03v21 10 20330 n

#

# The default device in the absence of a numeric or "-f device" argument

archive=/dev/rfd0135ds18 18 1440 n

$

從上面可以看出4代表/dev/rfd0135ds9設備，而默認的設備是/dev/rfd0135ds18，所以tar xvf /dev/rfd0135ds9 ./filename可以簡寫為tar xv4 ./filename,而tar cvf /dev/fd0135ds18 .可以簡寫為tar cv .