Command prompt and iTerm window dressing for BASH shells.

Just a quick one, this. After nearly a decade of inner guilt at using a C-shell I have finally switched over to a BASH shell. This required some hacking to get a prompt I could live with and interacted properly (set windows and tab titles etc) with iTerm2. The following line in my .bashrc:

 export PS1="\[\e]2;\u@\h:\w\[\a\]\[\e]1;\u@\h\[\a\][\h:\W]$ "

delivered what I was after:

Problems running gfortran compiled codes from MATLAB

A problem which had me stumped for a while was an apparent inability to run an executable compiled with gfortran from a MATLAB (v7.14) system() command (running on my 10.7.4 Mac). So, for trivial fortran code like:

program HelloWorld
write(*,*) 'hello world!'
end

compiled with gfortran (silently) returns no output when run from MATLAB with

>> [status, output] = system('./HelloWorld')
status =
     0
output =
     ''

After exploring the problem, I found out that the shell environment that MATLAB creates when system is called has a variable set called GFORTRAN_STDOUT_UNIT with a value of -1. This redirects stdout in gfortran to a file (usually fort.6), which is a fairly unhelpful, especially if you are doing something useful with stdout. Once you know this, you can work around it by unsetting the variable before doing anything else:

>> [status, output] = ...
       system('unset GFORTRAN_STDOUT_UNIT; ./HelloWorld')
status =
     0
output =
 Hello, world!

but it is a little clumsy. I have submitted a bug report to Mathworks, who have confirmed the behaviour and submitted it to the developer team. Also be aware that MATLAB monkeys about with other variables (for example, various directories are added to the beginning of your DYLD_LIBRARY_PATH, so if your executable relies on dylibs elsewhere there is the potential for collisions (for example, there is a version of one of the gfortran dylibs in one of paths added). You can also work around this, but it gets pretty ugly:

>> [status output] = ...
       system(['unset GFORTRAN_STDOUT_UNIT;...
               'export DYLD_LIBRARY_PATH=/usr/local/lib;', ...
               ' ./HelloWorld'])

You can find out what MATLAB has put in your environment by doing:

>> system('env')

Mac Eye for the Geophysics Guy now has a blog!

For ages I have been meaning to set up a blog associated with the website I maintain: Mac Eye for the Geophysics Guy. This webpage is a repository of information on setting up a Mac for use in the Earth Sciences, with a focus on Geophysics.

This blog will document things that I have discovered, problems I have solved (and that I haven't) which don't really merit documentation on the main page (which is probably too big now anyway). This is very largely for my own benefit, but if anything helps anyone else that's great too.

Enjoy!

Obviously, any views which appear here are entirely personal - they do not represent my employer, and they may not even accurately my own views at any given time. Information is provided in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.