其实以前也有发现DREAMHOST上面是有安装RAR的解压软件，只是原来一直没使用成功，最近很多国内服务器关闭，导致很多网站来迁移，而国内的主机基本上都是用的星外来管理的，备份都是RAR的，于是想研究下看到底DREAMHOST的空间能不能解压RAR的文件。
在网上搜了下，发现有人用rar e abc.rar这个命令可以成功解压，于是用PUTTY连接上空间后，传了个小文件试了下，果然不错，不过我后来才发现，这个命令是有问题的，这个命令会把所以有文件都放到当前目录下，也就是说原来的目录结构会没有，于是用rar help查看一下命令说明，才发现要保持目录结构的话要用rar x abc.rar这个命令，这下就OK了。
总结一下，解压RAR文件的方法是用PUTTY连接上FTP，然后用rar x abc.rar，abc.rar换成你自己的压缩包
以下是rar的说明，大家可以看一看
[castiglia]$ rar help
RAR 3.70 beta 1 Copyright (c) 1993-2007 Alexander Roshal 8 Jan 2007
Shareware version Type RAR -? for helpUsage: rar <command> -<switch 1> -<switch N> <archive> <files…>
<@listfiles…> <path_to_extract\><Commands>
a Add files to archive
c Add archive comment
cf Add files comment
ch Change archive parameters
cw Write archive comment to file
d Delete files from archive
e Extract files to current directory（解压到当前文件夹）
f Freshen files in archive
i[par]=<str> Find string in archives
k Lock archive
l[t,b] List archive [technical, bare]
m[f] Move to archive [files only]
p Print file to stdout
r Repair archive
rc Reconstruct missing volumes
rn Rename archived files
rr[N] Add data recovery record
rv[N] Create recovery volumes
s[name|-] Convert archive to or from SFX
t Test archive files
u Update files in archive
v[t,b] Verbosely list archive [technical,bare]
x Extract files with full path（以完整目录结构解压）<Switches>
– Stop switches scanning
ad Append archive name to destination path
ag[format] Generate archive name using the current date
ap<path> Set path inside archive
as Synchronize archive contents
av Put authenticity verification (registered versions only)
av- Disable authenticity verification check
c- Disable comments show
cfg- Disable read configuration
cl Convert names to lower case
cu Convert names to upper case
df Delete files after archiving
dh Open shared files
ds Disable name sort for solid archive
e[+]<attr> Set file exclude and include attributes
ed Do not add empty directories
en Do not put ‘end of archive’ block
ep Exclude paths from names
ep1 Exclude base directory from names
ep3 Expand paths to full including the drive letter
f Freshen files
hp[password] Encrypt both file data and headers
id[c,d,p,q] Disable messages
ierr Send all messages to stderr
ilog[name] Log errors to file (registered versions only)
inul Disable all messages
isnd Enable sound
k Lock archive
kb Keep broken extracted files
m<0..5> Set compression level (0-store…3-default…5-maximal)
mc<par> Set advanced compression parameters
md<size> Dictionary size in KB (64,128,256,512,1024,2048,4096 or A-G)
ms[ext;ext] Specify file types to store
n<file> Include only specified file
n@ Read file names to include from stdin
n@<list> Include files in specified list file
o+ Overwrite existing files
o- Do not overwrite existing files
ol Save symbolic links as the link instead of the file
or Rename files automatically
ow Save or restore file owner and group
p[password] Set password
p- Do not query password
r Recurse subdirectories
r0 Recurse subdirectories for wildcard names only
rr[N] Add data recovery record
rv[N] Create recovery volumes
s[<N>,v[-],e] Create solid archive
s- Disable solid archiving
sc<chr><obj> Specify the character set
sfx[name] Create SFX archive
si[name] Read data from standard input (stdin)
sl<size> Process files with size less than specified
sm<size> Process files with size more than specified
t Test files after archiving
ta<date> Process files modified after <date> in YYYYMMDDHHMMSS format
tb<date> Process files modified before <date> in YYYYMMDDHHMMSS format
tk Keep original archive time
tl Set archive time to latest file
tn<time> Process files newer than <time>
to<time> Process files older than <time>
ts<m,c,a>[N] Save or restore file time (modification, creation, access)
u Update files
v Create volumes with size autodetection or list all volumes
v<size>[k,b] Create volumes with size=<size>*1000 [*1024, *1]
ver[n] File version control
vn Use the old style volume naming scheme
vp Pause before each volume
w<path> Assign work directory
x<file> Exclude specified file
x@ Read file names to exclude from stdin
x@<list> Exclude files in specified list file
y Assume Yes on all queries
z[file] Read archive comment from file