Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

FORTRAN 90 command line arrgument

  1. Jun 20, 2011 #1
    Hi All,
    I am very new to FORTRAN Programming. The problem is related to commandline argument. i have a executable program which take 3 command line argument as an input. one is text file and two is variable. I want to write a script were i can execute this script and save in different file and should be able to change the arguments. for example;

    ./exe1 input.txt x x[j] > output.txt

    i=j=1 ... 10

    Any help or suggestion will be appreciated. Please let me know if any other information is neede.

    Thank you
  2. jcsd
  3. Jun 20, 2011 #2


    Staff: Mentor

    According to this web page, you can use the getarg() subroutine to get the i-th command line argument.

    Code (Text):

              PROGRAM test_getarg
                INTEGER :: i
                CHARACTER(len=32) :: arg
                DO i = 1, iargc()
                  CALL getarg(i, arg)
                  WRITE (*,*) arg
                END DO
              END PROGRAM
    Your description of what you're trying to do is not very clear, particularly what you need to do with the two variables on the command line. Can be give a clearer description?
  4. Jun 20, 2011 #3
    Thank you so much for your help and sorry for confusion.

    beside input.txt file i have one more input file which have 10 variable (x1,x2...x10) and i would like to make a script which read nested loop to read and compute x1 and x1 and for next iteration it should consider x1 and x2.. and so on such that this script will give me n*n metrix..

    and save this ouput in new output.txt file ..

    if still some confusion please let me know...

    Thank you for your advise
  5. Jun 20, 2011 #4


    Staff: Mentor

    Why do you need two input files?
    The input file almost certainly doesn't contain variables - it contains numbers. Variables are what your program (which is NOT a script) uses to store numbers.

    What do you mean "read and compute x1 and x1?"
    How will your program "consider" x1 and x2?

    I still don't know what you're trying to do.
  6. Jun 21, 2011 #5
    sorry for the confusion again as i told you before very new to FORTRAN I need to run this for my research.. so thought ask for help....

    I haven't made this ./exe program i am just using it and to execute this ./exe we need 3 arguments one is input.txt file and other two are variables such as X and Y..

    but i want to run this ./exe for more than 10 times .. if i want i can do it manually by entering all the values of X and Y one by one... but i want to know if there is any way i can write a program such that itself read another file which contains values of X and Y and execute ./exe

    i know how to do this in R or C ... but my less knowledge in Fortran is giving me hard time.

    if still not clear than let me put it in this way

    do i till 10

    do j till 10

    ./exe input.txt x x[j] >> output.txt !but i want to amend all the output in one file

    end do

    end do
  7. Jun 21, 2011 #6


    Staff: Mentor

    Why don't you write the code you want in C, since you're more familiar with that than you are with Fortran?
  8. Jun 25, 2011 #7
    If the fortran exe file is already compiled and all you want to do is run it a few times, what you need to do is write a script for the shell you are accustom to run the fortran, in the first place...

    so, if you use a terminal with bash, just write a script that takes two arguments (names of the two files, the one input file and the one with the x's)...then, make the loop at the bash level and execute the fortran program from there.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook