proc_env.f90

! -*- Mode:F90; Coding:us-ascii-unix; fill-column:129 -*-
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.H.S.!!
!!
! @file      proc_env.f90
! @author    Mitch Richling http://www.mitchr.me/
! @brief     How to access environment variables. @EOL
! @std       F2003 
! @copyright 
!  @parblock
!  Copyright (c) 2024, Mitchell Jay Richling <http://www.mitchr.me/> All
!  rights reserved.
!
!  Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
!  conditions are met:
!
!  1. Redistributions of source code must retain the above copyright notice, this list of conditions, and the following
!     disclaimer.
!
!  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions, and the following
!     disclaimer in the documentation and/or other materials provided with the distribution.
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!  3. Neither the name of the copyright holder nor the names of its contributors may be used to endorse or promote products
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!
!  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
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!  SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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!  @endparblock
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!##################################################################################################################################
program proc_env

  implicit none

  integer                       :: ierror = 0
  integer                       :: e_var_len
  character(len=:), allocatable :: e_var_val

  

  call get_environment_variable('PATH', length=e_var_len, status=ierror, trim_name=.false.)

  if(ierror /= 0) then
     print *, ierror
     stop 'ERROR: Unable to fine PATH environment variable'
  end if

  print '(a,i0,a)', 'PATH variable found, and is ', e_var_len, ' characters long.'

  ! Now that we know how long the string is, we allocate the e_var_val variable
  allocate(character(len=e_var_len) :: e_var_val)

  ! Now that we have space for the string, we query it.
  call get_environment_variable('PATH', e_var_val, e_var_len, ierror, .FALSE.)

  if(ierror /= 0) then
     print '(a,i0,a)', 'Something went wrong.  Received error code: ', ierror, ' from get_environment_variable'
  else
     print '(a)', 'PATH variable value is:'
     print '(4x,a)', e_var_val
  end if

end program proc_env