du命令参数详解见： http://baike.baidu.com/view/43913.htm
下面我们只对其做简单介绍；
查看linux文件目录的大小和文件夹包含的文件数
统计总数大小
du -sh filename（其实我们经常用du -sh *，显示当前目录下所有的文件及其大小，如果要排序再在后面加上 | sort -n）
du -sm * | sort -n //统计当前目录大小 并按大小 排序
du -sk * | sort -n
du -sk * | grep filename //查看一个文件夹的大小
du -m | cut -d "/" -f 2 //看第二个/ 字符前的文字
查看此文件夹有多少文件 /*/*/* 有多少文件
du filename/
du filename/*/*/* |wc -l
40752
解释：
wc [-lmw]
参数说明：
-l :多少行
-m:多少字符
-w:多少字
或者也可以打开Nautilus窗口（文件夹首选项），点击“编辑”-“首选项”，切换到“显示”标签，改变“图标标题”下面的树形列表的内容为“大小，修改日期、类型”。设置立即生效。现在在文件图标的下面会显示文件的大小。
PS：
df -hl 查看磁盘剩余空间
du -sm 文件夹
返回该文件夹总M数
更多功能查看：
df --help
du --help
du --help
用法：du [选项]... [文件]...
总结每个<文件>的磁盘用量，目录则取总用量。
用法：du [选项]... [文件]...
总结每个<文件>的磁盘用量，目录则取总用量。
长选项必须用的参数在使用短选项时也是必须的。
-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 显示此帮助信息并离开
--version 显示版本信息并离开
-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 显示此帮助信息并离开
--version 显示版本信息并离开