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Full Discussion: UNIX $USER and $LOGNAME environment variables
Top Forums Shell Programming and Scripting UNIX $USER and $LOGNAME environment variables Post 303015932 by bakunin on Monday 16th of April 2018 04:41:53 PM
Old 04-16-2018
Quote:
Originally Posted by lsatenstein
[LEFT]I have some comments about a previously closed topic whose name is the same as above

Omitted from the discussion was the situation with a "sudo command or sudo within a script".

There is an inconsistency between systems. On some systems $LOGNAME is invariant, on others,

on RedHat sudo su and echo $LOGNAME reports the name of the person invoking sudo.
on SUSE, sudo su and echo $LOGNAME reports root. $LOGNAME and $USER report root

Here is a workaround that I discovered and propose:

sudo xxx or sudo su sets up an environment variable SUDO_USER, SUDO_UID,SUDO_GID, and SUDO_COMMAND

It always reports the name of the logon invoking sudo (the caller)

What happens when I sudo su and as root su a third_user?
my system says $LOGNAME and $USER contain the "third_user" id. But
SUDO was invariant

I did not check what happens if the third_user issues as I have liimited my admin logon to one ID.

Please evaluate this posting and re-open that above mentioned topic to see if it is worth merging them together.
I have no idea which thread you are referring to, perhaps you can provide a link to this thread?

Anyway, variables like "$LOGNAME" or "$USER" may be common but are in no way standardised (and even less is their content) and hence it is bad practice to rely on any of them. I suggest you use the id command to get the current user ID.

If you want a script you call via sudo to know from which UID it has been called use an argument to do so. Consider this template command:

Code:
sudo su - root -c /some/command -abc arg1 arg2

its call could be turned into:

Code:
chUser="$(id -un)"
sudo su - root -c /some/command -abc "$chUser" arg1 arg2

and subsequently you could inspect the arguments inside /some/command to find out by whom you have been called. Wouldn't that be a more robust way than to rely on some variables which may be defined readonly on one system and different on another?

I hope this helps.

bakunin
 

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LEARN ABOUT DEBIAN

viewsudo

VIEW-OS(1)						      General Commands Manual							VIEW-OS(1)

NAME

       viewsudo - execute a command as another (virtual) user

SYNOPSIS

       viewsudo [-g groupname|#gid] [-u username|#uid] command

DESCRIPTION

       viewsudo allows a user to execute a command as the superuser or
	      another user in View-OS.

OPTIONS

       viewsudo accepts the following command line options:

       -g group
	   Normally,  viewsudo	sets the primary group to root.  The -g option causes sudo to run the specified command with the primary group set
	   to group.  To specify a gid instead of a group name, use #gid.  When running commands as a gid, many shells require	that  the  '#'	be
	   escaped  with  a  backslash	('[u2019]).   If  no -u option is specified, the command will be run as the invoking user (not root).	In
	   either case, the primary group will be set to group.

       -u user
	   The -u option causes viewsudo to run the specified command as a user other than root.  To specify a uid instead of  a  user	name,  use
	   #uid.  When running commands as a uid, many shells require that the '#' be escaped with a backslash ('[u2019]).

RETURN VALUES

       Upon successful execution of a program, the exit status from viewsudo will simply be the exit status of the program that was executed.

SEE ALSO

       viewsu(1), sudo(1), linux.defs(5)

AUTHORS

       View-OS is a project of the Computer Science Department, University of Bologna. Project Leader: Renzo Davoli.
       <http://www.sourceforge.net/projects/view-os>

       Howto's and further information can be found on the project wiki <wiki.virtualsquare.org>.

NOTE

       Most part of the text is taken from sudo(1).

VIEW-OS: a process with a view					  August 8, 2009							VIEW-OS(1)
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