/etc/shells文件用途

/etc/shells文件用途

 

一直对/etc/shells这个文件的作用不是太清楚，最近抽时间查了查，总结如下。

$ man shells

SHELLS(5) Linux Programmer’s Manual SHELLS(5)

NAME

shells - pathnames of valid login shells

DESCRIPTION

/etc/shells is a text file which contains the full pathnames of valid login shells.

This file is consulted by chsh(1) and available to be queried by other programs.

Be aware that there are programs which consult this file to find out if a user is a

normal user. E.g.: ftp daemons traditionally disallow access to users with shells

not included in this file.

EXAMPLE

/etc/shells may contain the following paths:

/bin/sh

/bin/csh

FILES

/etc/shells

SEE ALSO

chsh(1), getusershell(3)

1993-11-21 SHELLS(5)

/etc/shells是一个有效登陆shell的列表，在调用chsh改变登陆shell时，会查询这个文件。

[root@winway ~]# cat /etc/shells

/bin/sh

/bin/bash

/sbin/nologin

/bin/tcsh

/bin/csh

/bin/ksh

 

[winway@winway ~]$ chsh

Changing shell for winway.

口令：

New shell [/bin/bash]: /bin/date

chsh: "/bin/date" is not listed in /etc/shells.

chsh: use -l option to see list

       由于/bin/date/不在/etc/shells里，所以普通用户调用chsh失败。root调用会出现warning。

 

[root@winway ~]# echo '/bin/date' >>/etc/shells

 

[winway@winway ~]$ chsh -l

/bin/sh

/bin/bash

/sbin/nologin

/bin/tcsh

/bin/csh

/bin/ksh

/bin/date

[winway@winway ~]$ chsh

Changing shell for winway.

口令：

New shell [/bin/bash]: /bin/date

Shell changed.

[winway@winway ~]$ grep 'winway' /etc/passwd

winway:x:500:500:ww,isrc,no,no:/home/winway:/bin/date

另外一些程序会根据这个文件来判断一个用户是否是有效用户，例如FTP服务会组织那些shell不在/etc/shells里的用户登陆。