CODEWITHSUNDEEP
fortranenvironment-variableshostname
EMiller
EMiller

Reputation: 2842

What environment variables are presented to a Fortran program for GET_ENVIRONMENT_VARIABLE

I would like to use the value of the $HOSTNAME environment variable in my Fortran code.

My attempt to do so is:

   CHARACTER(LEN=100) :: hostname
   INTEGER :: status_value = 0

   CALL GET_ENVIRONMENT_VARIABLE("hostname",hostname, STATUS=status_value) 

   IF (status_value == 2) THEN 
     WRITE(nout,*) 'WARNING: Processor does not support environment variables - hostname is unknown.'
     hostname = 'Unknown'
   ELSE IF (status_value == -1) THEN 
     WRITE(nout,*) 'WARNING: Hostname is too long for character variable - hostname is truncated.'
   ELSE IF (status_value == 1) THEN 
     WRITE(nout,*) 'WARNING: $HOSTNAME environment variable does not exist - hostname is unknown.'
     hostname = 'Unknown'

But my result is that I always get the result that $HOSTNAME does not exist.

My interpretation of the status value is based on this: http://gcc.gnu.org/onlinedocs/gfortran/GET_005fENVIRONMENT_005fVARIABLE.html

Interestingly, the example at the above page uses the 'HOME' environment variable. This environment variable works for me.

But I see no reason why $HOSTNAME should not:

    MacBook-Pro:1N45 emiller$ echo $HOSTNAME  # My shell prompt
    MacBook-Pro.local

What is going on? What environment does my Fortran program see at runtime?

For what it's worth, I am using iFort 12.

Upvotes: 3

Views: 1613

Answers (1)

Jonathan Dursi
Jonathan Dursi

Reputation: 50937

This actually works fine, but on most platforms, these environment variable names are case sensitive. I get your results on my linux box with gfortran or ifort, but if I change your "hostname" string to "HOSTNAME" I get the expected results.

Upvotes: 9

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