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Re: New su behavior in util-linux 2.32



https://www.mycause.com.au/page/183259/a-smile-will-change-a-day-love-that-changed-my-world

From: Pétùr <peturvilj@gmail.com>
Sent: Saturday, 11 August 2018 7:41 PM
To: debian-user
Subject: New su behavior in util-linux 2.32
 
Using 'su' generates now an path error when launching programs such as 'shutdown'. The cause is a new behavior described below.
---
util-linux (2.32-0.4) unstable; urgency=medium

  The util-linux implementation of /bin/su is now used, replacing the
  one previously supplied by src:shadow (shipped in login package), and
  bringing Debian in line with other modern distributions. The two
  implementations are very similar but have some minor differences (and
  there might be more that was not yet noticed ofcourse), e.g.

  - new 'su' (with no args, i.e. when preserving the environment) also
    preserves PATH and IFS, while old su would always reset PATH and IFS
    even in 'preserve environment' mode.
  - su '' (empty user string) used to give root, but now returns an error.
  - previously su only had one pam config, but now 'su -' is configured
    separately in /etc/pam.d/su-l

  The first difference is probably the most user visible one. Doing
  plain 'su' is a really bad idea for many reasons, so using 'su -' is
  strongly recommended to always get a newly set up environment similar
  to a normal login. If you want to restore behaviour more similar to
  the previous one you can add 'ALWAYS_SET_PATH yes' in /etc/login.defs.
---

The new 'su' is useless for me because it cannot launch root program.
I did the modification in /etc/login.defs and restore the previous
behavior. However I am concern with the statement " Doing plain 'su'
is a really bad idea for many reasons".

Could someone explain to me why this is a bad behavior?

Pétùr


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