1.命令cat /etc/shells
[tansheng@localhost ~]$ cat /etc/shells /bin/sh /bin/bash /sbin/nologin /bin/dash /bin/tcsh /bin/csh [tansheng@localhost ~]$
2./bin/sh是最原始的shell,现在几乎所有的linux都把bash shell设为默认的shell,即使/bin/sh 也是链接至/bin/bash
[tansheng@localhost ~]$ ls -l /bin/sh lrwxrwxrwx. 1 root root 4 10月 12 01:59 /bin/sh -> bash [tansheng@localhost ~]$
原文：http://www.cnblogs.com/ttss/p/4195473.html