i am using redhat linux 7.9 x86_64
i have created two user oracle and grid.
i have added both the user to wheel group.

when i try to run command from oracle user
[oracle$srv1]$su grid
password-xxxxxxx

su:Authentication failure


[root@srv1~]#getfacl /usr/bin/su
# file: usr/bin/su
# owner: root
# group: root
user::rwx
group::rwx
other::r-x

on other m/c i have checked group permission as below,
on that m/c su grid command work without Authentication issue.
[root@srv2 /]# getfacl usr/bin/su
# file: usr/bin/su
# owner: root
# group: root
# flags: s--
user::rwx
group::r-x
other::r-x

here it show one more field called #flags: s--
i do not get this, how this flags appear here?


can any one known for this error solution?

probably you used an incorrect password, you should enter the password of root, not the password of the user.

i have given password of root, previously it was working
it is working on other m/c,
there is some extra permission on that m/c when i runt getfacl /usr/bin/su
#flags:s--
might be something related to this

that is required as far as I know

how it appears flags:s--, this is the difference i have
noted on working m/c and not working m/c.
because earlier i have added the user to
wheel group and then it is started working
without any issue.

The -s flag makes su run as root even though it's invoked by an ordinary user, which is what it needs to do in order to work. If you don't have this flag set on the affected machine, then su was wrongly installed. I think it's part of the shadow package; you could try reinstalling that.

Or you could try logging on as root and using chmod to set the flag correctly.

please tell me how to run chmod command exactly. ?

it has been resolved by running following two command

[root@srv1 /]# chown root:root /usr/bin/sudo
[root@srv1 /]# chmod 4755 /usr/bin/sudo

and

[root@srv1 /]# chown root:root /usr/bin/su
[root@srv1 /]# chmod 4755 /usr/bin/su