Off-Topic: ${LOGNAME} vs. ${USER}

[silver.bullet at zoho.com]

On Fri, 31 Jul 2015 02:56:16 -0400 Tom H wrote:
> I don't use Arch but I suspect from the above output that its
> "/bin/su" is provided by "util-linux", like Fedora/RHEL, rather than
> by "login", which is derived from the "shadow" source package.
> 
> For util-linux
> $HOME, $SHELL
> are reset
> and
> $LOGNAME, $USER
> are reset if the target user is not root
> 
> For login/shadow
> $HOME, $LOGNAME, $PATH, $SHELL, $USER
> are reset
> 
> AFAIR, in the util-linux case, $PATH used to behave like $LOGNAME and
> $USER but it's no longer reset (but there's a login.defs variable for
> it to be reset).

Thank you Tom,

it's useful to know such things, to keep scripts compatible for usage
with different Linux distros and operating systems.

Your guess is correct.

[rocketmouse at archlinux ~]$ pacman -Qo /usr/bin/su
/usr/bin/su is owned by util-linux 2.26.2-1

Regards,
Ralf

PS:

FHS Ubuntu

[rocketmouse at archlinux ~]$ p="/mnt/moonstudio"
[rocketmouse at archlinux ~]$ ls -hAld $p/bin $p/sbin $p/usr/bin/
$p/usr/sbin
drwxr-xr-x 2 root root 4.0K Jul 26 15:48 /mnt/moonstudio/bin
drwxr-xr-x 2 root root 4.0K Jul 30 14:38 /mnt/moonstudio/sbin
drwxr-xr-x 2 root root  36K Jul 31 10:26 /mnt/moonstudio/usr/bin/
drwxr-xr-x 2 root root 4.0K Jul 31 10:25 /mnt/moonstudio/usr/sbin

FHS Arch

[rocketmouse at archlinux ~]$ p=""
[rocketmouse at archlinux ~]$ ls -hAld $p/bin $p/sbin $p/usr/bin/
$p/usr/sbin
lrwxrwxrwx 1 root root    7 Apr 22 17:51 /bin -> usr/bin
lrwxrwxrwx 1 root root    7 Apr 22 17:54 /sbin -> usr/bin
drwxr-xr-x 5 root root 212K Jul 30 16:28 /usr/bin/
lrwxrwxrwx 1 root root    3 Apr 22 17:57 /usr/sbin -> bin



I noticed that by default Ubuntu's /tmp isn't tmpfs

[rocketmouse at archlinux ~]$ ls -a /mnt/moonstudio/tmp/
.                   .spamassassin102421p50xJtmp  .spamassassin10242DBmUqjtmp  .spamassassin10242XZLXCitmp
..                  .spamassassin102424Cvbvktmp  .spamassassin10242edxaWAtmp  .spamassassin10242zKWRtntmp
config-err-SL5T3l   .spamassassin102424d72xatmp  .spamassassin10242FWYa7xtmp  .Test-unix
.font-unix          .spamassassin102424IF1kitmp  .spamassassin10242mRPxB3tmp  .X11-unix
.ICE-unix           .spamassassin10242cLW8dJtmp  .spamassassin10242oi0hf7tmp  .XIM-unix
qupzilla-weremouse  .spamassassin10242CwrMp8tmp  .spamassassin10242w4NwR9tmp

Default for Arch is tmpfs

[rocketmouse at archlinux ~]$ df | grep /tmp
tmpfs            1895600      112   1895488   1% /tmp