[SOLVED] unknown bash command?

fanoflq · 01-16-2017, 12:14 PM

unknown bash command?

I look at many places, but could not find
bash information for d, gn and un.

I saw this fragment for bash:

Code:

 [ "`d -gn`“ : "‘`d -un`”

What are d, gn and un?
Thanks.

rtmistler · 01-16-2017, 12:21 PM

d is obviously an abbreviation for one bash command, and -gn -un are arguments it accepts.

I thought possibly "date", however it does not appear to have those arguments, or at least mine does not.

Any more details about how it is used?

Where did you get that from? Someone's script? Horrible script writer if so.

hydrurga · 01-16-2017, 01:07 PM

It looks as if it may have come from here (bottom answer): http://unix.stackexchange.com/questi...rs-under-linux

where it is:

Code:

[ "`id -gn`" = "`id -un`" ]

rtmistler · 01-16-2017, 01:11 PM

Excellent find hydrurga.

Well obviously it was misquoted or "found" somewhere else where it was already corrupted from it's original form.

fanoflq · 01-16-2017, 01:11 PM

Thank you for responding.....

Quote:

Originally Posted by rtmistler

d is obviously an abbreviation for one bash command, and -gn -un are arguments it accepts.

I thought possibly "date", however it does not appear to have those arguments, or at least mine does not.

Any more details about how it is used?

Where did you get that from? Someone's script? Horrible script writer if so.

It is from a RHCSA study guide book 7th edition, by Michael Jung.
Ops... I have to make corrections....

Excerpts:

Code:

The Default umask
With that in mind, the default umask is driven by the /etc/proﬁle and /etc/bashrc
ﬁles, speciﬁcally the following stanza, which drives a value for umask depending on
the value of the UID:

if [ $UID -gt 199 ] && [ "`id -gn`“ = "‘`id -un`” ]; then
	umask 002
else
	umask 022
fi

In other words, the umask for user accounts with UIDs of 200 and above is 002.
In contrast, the umask for UIDs below 200 is 022. In RHEL 7, service users such as
adm, postﬁX, and apache have lower UIDs; this affects primarily the permissions of
the log ﬁles created for such services. Of course, the root administrative user has
the lowest UID of 0. By default, ﬁles created for such users have 644 permissions;
directories created for such users have 755 permissions.

In contrast, regular users have a UID of 1000 and above. Files created by such
users normally have 664 permissions. Directories created by such users normally
have 775 permissions. Users can override the default settings by appending an
umask command in their ~/.bashrc or ~/.bash_proﬁle.

The error on my part is "d" command should be "id" command.
Now I know what id is,.
I can now guess what gn and un are, i.e. group name and user name.
but I was not able to find it in bash documentation....

rtmistler · 01-16-2017, 01:12 PM

If that's really what the book quotes, then write to the publisher and inform them that they have an error.

Turbocapitalist · 01-16-2017, 01:16 PM

As for the pieces, the [ is like the program test. The backticks ` are command substitution and could better be written as $( … )

fanoflq · 01-16-2017, 01:17 PM

Sorry folks.
Please see corrections in original post.
Thank you.

rtmistler · 01-16-2017, 01:20 PM

Quote:

Originally Posted by fanoflq

Sorry folks.
Please see corrections in original post.
Thank you.

OK, it's not a publication error. The command is also no longer an unknown, you should be able to review the manual page to see that it is used to print user and group information.

Does this resolve you question?

fanoflq · 01-16-2017, 01:23 PM

Quote:

Originally Posted by rtmistler

OK, it's not a publication error. The command is also no longer an unknown, you should be able to review the manual page to see that it is used to print user and group information.

Does this resolve you question?

Thank you.
I found the answer in here: man id