du命令引數詳解見： http://baike.baidu.com/view/43913.htm
下面我們只對其做簡單介紹；
檢視linux檔案目錄的大小和資料夾包含的檔案數
統計總數大小
du -sh filename（其實我們經常用du -sh *，顯示當前目錄下所有的檔案及其大小，如果要排序再在後面加上 | sort -n）
du -sm * | sort -n //統計當前目錄大小 並按大小 排序
du -sk * | sort -n
du -sk * | grep filename //檢視一個資料夾的大小
du -m | cut -d "/" -f 2 //看第二個/ 字元前的文字
檢視此資料夾有多少檔案 /*/*/* 有多少檔案
du filename/
du filename/*/*/* |wc -l
40752
解釋：
wc [-lmw]
引數說明：
-l :多少行
-m:多少字元
-w:多少字
或者也可以開啟Nautilus視窗（資料夾首選項），點選“編輯”-“首選項”，切換到“顯示”標籤，改變“圖示標題”下面的樹形列表的內容為“大小，修改日期、型別”。設定立即生效。現在在檔案圖示的下面會顯示檔案的大小。
PS：
du --help
用法：du [選項]... [檔案]...
總結每個<檔案>的磁碟用量，目錄則取總用量。
長選項必須用的引數在使用短選項時也是必須的。
-a, --all write counts for all files, not just directories
--apparent-size print apparent sizes, rather than disk usage; although
the apparent size is usually smaller, it may be
larger due to holes in (`sparse') files, internal
fragmentation, indirect blocks, and the like
-B, --block-size=SIZE use SIZE-byte blocks
-b, --bytes equivalent to `--apparent-size --block-size=1'
-c, --total produce a grand total
-D, --dereference-args dereference FILEs that are symbolic links
-H like --si, but also evokes a warning; will soon
change to be equivalent to --dereference-args (-D)
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
--si like -h, but use powers of 1000 not 1024
-k like --block-size=1K
-l, --count-links count sizes many times if hard linked
-L, --dereference dereference all symbolic links
-P, --no-dereference don't follow any symbolic links (this is the default)
-0, --null end each output line with 0 byte rather than newline
-S, --separate-dirs do not include size of subdirectories
-s, --summarize display only a total for each argument
-x, --one-file-system skip directories on different filesystems
-X FILE, --exclude-from=FILE Exclude files that match any pattern in FILE.
--exclude=PATTERN Exclude files that match PATTERN.
--max-depth=N print the total for a directory (or file, with --all)
only if it is N or fewer levels below the command
line argument; --max-depth=0 is the same as
--summarize
--help 顯示此幫助資訊並離開
--version 顯示版本資訊並離開
-a, --all write counts for all files, not just directories
--apparent-size print apparent sizes, rather than disk usage; although
the apparent size is usually smaller, it may be
larger due to holes in (`sparse') files, internal
fragmentation, indirect blocks, and the like
-B, --block-size=SIZE use SIZE-byte blocks
-b, --bytes equivalent to `--apparent-size --block-size=1'
-c, --total produce a grand total
-D, --dereference-args dereference FILEs that are symbolic links
-H like --si, but also evokes a warning; will soon
change to be equivalent to --dereference-args (-D)
-h, --human-readable print sizes in human readable format (e.g., 1K 234M 2G)
--si like -h, but use powers of 1000 not 1024
-k like --block-size=1K
-l, --count-links count sizes many times if hard linked
-L, --dereference dereference all symbolic links
-P, --no-dereference don't follow any symbolic links (this is the default)
-0, --null end each output line with 0 byte rather than newline
-S, --separate-dirs do not include size of subdirectories
-s, --summarize display only a total for each argument
-x, --one-file-system skip directories on different filesystems
-X FILE, --exclude-from=FILE Exclude files that match any pattern in FILE.
--exclude=PATTERN Exclude files that match PATTERN.
--max-depth=N print the total for a directory (or file, with --all)
only if it is N or fewer levels below the command
line argument; --max-depth=0 is the same as
--summarize
--help 顯示此幫助資訊並離開
--version 顯示版本資訊並離開
eg: du -smh oracle
54G //顯示oracle資料夾的大小為54G