How do I change the path that is being searched for launching an application? I am trying to launch the D programming language compiler DMD, but the terminal is giving the following error:

dmd: failed to launch executable at /Library/Compilers/dmd2/osx/bin/dmd


But there's not folder called dmd2 under /Library/Compilers. 

I can launch the dmd compiler from this path /usr/bin/dmd, but I don't want to type this path every time I need to compile a source code file. 

This is my $PATH:


  /Library/Frameworks/Python.framework/Versions/2.7/bin:/Library/Frameworks/Python.framework/Versions/3.4/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/texbin


Is there a way that when I type dmd it launches /usr/bin/dmd, instead of trying to language a compiler under /Library/Compilers/dmd2/osx/bin/dmd?
To answer your question, your PATH has to be modified to:

PATH=/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/Library/Frameworks/Python.framework/Versions/2.7/bin:/Library/Frameworks/Python.framework/Versions/3.4/bin:/opt/X11/bin:/usr/texbin


so that your shell will find
    /usr/bin/dmd
before any other one called from within one of the 2 Python library directories.

Please note: it is a dangerous practice to let any software not distributed by Apple to install anything within /usr/bin (or /bin, /sbin or /usr/sbin). This is a technic used by crapware to hide themself.