查看Linux系统是否为64位的方法

可以直接使用 file /sbin/init 查看当前Linux系统是否为64位系统。

[root@fedora13 ~]# file /sbin/init
/sbin/init: ELF 32-bit LSB executable, Intel 80386, version 1 (GNU/Linux), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped

上面的红色字体就是表示该文件时在32位的系统上的可执行文件。

其实，只要用 file 命令来查看任何一个在电脑上的可执行文件（如用gcc编译生成的可执行文件）都可以查看到相似的结果。

 /sbin/init 文件的作用：

The /sbin/init program (also called init) coordinates the rest of the boot process and configures the environment for the user.

When the init command starts, it becomes the parent or grandparent of all of the processes that start up automatically on the system. First, it runs the /etc/rc.d/rc.sysinit script, which sets the environment path, starts swap, checks the file systems, and executes all other steps required for system initialization. For example, most systems use a clock, so rc.sysinit  reads the /etc/sysconfig/clock configuration file to initialize the hardware clock. Another example is if there are special serial port processes which must be initialized, rc.sysinit  executes the /etc/rc.serial file.

The init command then runs the /etc/inittab script, which describes how the system should be set up in each SysV init runlevel. Runlevels are a state, or mode, defined by the services listed in the SysV /etc/rc.d/rc<x>.d/ directory, where <x> is the number of the runlevel.

Next, the init command sets the source function library, /etc/rc.d/init.d/functions, for the system, which configures how to start, kill, and determine the PID of a program.

The init program starts all of the background processes by looking in the appropriate rc  directory for the runlevel specified as the default in /etc/inittab . The rc directories are numbered to correspond to the runlevel they represent. For instance, /etc/rc.d/rc5.d/ is the directory for runlevel 5.