/bin与/usr/bin的区别

/bin是超级用户和一般用户都可以使用的命令；

/usr/bin是安装的软件的命令  

usr表示的是unix software source

/bin 二进制可执行命令
/sbin 系统管理命令，这里存放的是系统管理员使用的管理程序
/usr/bin 众多的应用程序
/usr/sbin 超级用户的一些管理程序

According to the FHS, the / directory must contain, or have
links to, the following directories:

bin — This directory contains command files for use by the
system administrator or other users. The bin directory can
not contain subdirectories.

boot — On Red Hat systems, this is the directory
containing the kernel, the core of the operating system. Also
in this directory are files related to booting the system, such
as the bootloader.

dev — This directory contains files with information about
devices, either hardware or software devices, on the system.

etc — This directory and its subdirectories contain most of
the system configuration files. If you have the X Window
System installed on your system, the X11 subdirectory is
located here. Networking related files are in the subdirectory
sysconfig.
Another subdirectory of etc is the skel directory, which is
used to create files in users’ home directories when the users
are created.

home — This directory contains the directories of users on
the system. Subdirectories of home will be named for the
user to whom they belong.

lib — The shared system files and kernel modules are
contained in this directory and its subdirectories.

mnt — This directory is the location of the mount point for
temporary file systems, such as a floppy or CD.

opt — This directory and its subdirectories are often used
to hold applications installed on the system.

proc — Information about system processes is included in
this directory.

root — This is the home directory of the root user. Don’t
confuse this with the / directory, which has the same name.

sbin — Contained in this directory are system binaries
used by the system administrator or the root user.

tmp — This directory contains temporary files used by the
system.

usr — This directory is often mounted on its own partition.
It contains shareable, read-only data. Subdirectories can be
used for applications,
typically under /usr/local.

var — Subdirectories and files under var contain variable
information, such as system logs and print queues

【Some important /proc files are】：
/proc/cpuinfo — contains info about the CPU
/proc/interrupts — tells you what interrupts are in use
/proc/scsi — tells you what kind of SCSI adapter is installed
/proc/parport — contains info about the parallel ports on
your system
/proc/tty — contains info about ttys that are available and in
use
/proc/apm — contains advanced power management
information
/proc/bus — a directory that contains bus-specific
information
/proc/devices — lists available character and block devices
/proc/dma — lists used DMS channels
/proc/filesystems — lists supported file systems
/proc/fs — contains file system parameters
/proc/ide — directory that contains information about the IDE
subsystem
/proc/ioports — contains information about system I/O port
usage
/proc/modules — contains a list of currently loaded modules
/proc/net — contains networking information
/proc/uptime — contains the system uptime
/proc/version — contains the system version