Linux – Why does the LD_LIBRARY_PATH get unset launching terminal

environment-variableslinuxshellterminal

I have a shell script to set up some environment variables and launch whatever program I send in as an argument:

export PATH=$HOME/local/bin:$PATH
export LD_LIBRARY_PATH=$HOME/local/lib:$LD_LIBRARY_PATH
export TESTER="MY TEST VAR"

$@

When I use this to call bash for example it works:

kjfletch@flatbed:~$ envrun.sh bash
kjfletch@flatbed:~$ echo $LD_LIBRARY_PATH
/home/kjfletch/local/lib:
kjfletch@flatbed:~$ echo $TESTER
MY TEST VAR

When I use it to call a terminal (xterm, aterm, …) my LD_LIBRARY_PATH gets unset:

kjfletch@flatbed:~$ echo $LD_LIBRARY_PATH

kjfletch@flatbed:~$ echo $TESTER

MY TEST VAR

Why does this happen? How can I stop this? (I am running Debian 5.0)

Update

My terminal is not calling bash as a login:

kjfletch@flatbed:~$ echo $0
bash

My LD_LIBRARY_PATH does not show up in any of the bash startup files (apart from .bash_history and ~/.profile does not exist.):

kjfletch@flatbed:~$ grep "LD" ~/.bash*
kjfletch@flatbed:~$ grep "LD" /etc/bash.bashrc 
kjfletch@flatbed:~$ grep "LD" /etc/profile

Best Answer

The terminal binary is most likely setgid to group utmp. Setuid and setgid binaries unset LD_LIBRARY_PATH for security reasons; see ld.so(8):

The necessary shared libraries needed by the program are searched for in the following order

  • Using the environment variable LD_LIBRARY_PATH (LD_AOUT_LIBRARY_PATH for a.out programs). Except if the executable is a setuid/setgid binary, in which case it is ignored.
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