# Use Other Methods to Set Environment Variables

## All Operating Systems

From within a program: Call the SETENVQQ routine to set environment variables. For example:

    USE IFPORT
    LOGICAL success
    success = SETENVQQ(“FORT9=C:\mydir\test.dat”)

Depending on your operating system, there are additional ways to set environment variables.

## Linux* and macOS

Within the Bourne*/Bourne* Again shell (sh/bash), or the Korn shell (ksh), use the export command and assignment command to set an environment variable:

    export FORT9
    FORT9=/usr/users/smith/test.dat

To remove the association of an environment variable and its value within the Bourne*, Korn shell, or bash shells, use the unset command:

    unset FORT9

Within the C shell (csh), use the setenv command to set an environment variable:

    setenv FORT9 /usr/users/smith/test.dat

To remove the association of an environment variable and its value within the C shell, use the unsetenv command.

    unsetenv FORT9

## Windows*

Environment variables in a command prompt session can be set using the SET command. Changes here will affect programs run from that command prompt only. For example:

    set FORT9=C:\mydir\test.dat

To remove an environment variable, omit the value. For example:

    set FORT9=

To display the current value, use the ECHO command and enclose the environment variable name in the percent signs as shown below:

    echo %FORT9%

To display the values of all variables whose names begin with a string, use SET and omit the equal sign as shown below:

    set FORT

In Microsoft Visual Studio you can specify environment variables that will be set when a program is run. In the project properties, edit the Configuration Properties > Debugging > Environment property and set the field to a series of name=value pairs separated by semicolons. For example:

    FORT9=C:\mydir\test.dat;FOR_FORCE_STACK_TRACE=TRUE

A default set of environment variables is established per user and at the system level. These can be specified through Control Panel > System > Advanced System Settings > Environment Variables.

### Note

Changing system-wide environment variables affects command line builds (those done without IDE involvement), but not builds done through the IDE. IDE builds are managed in the IDE using Tools > Options. An exception to this is an IDE build (devenv) done from the command line that specifies the useenv option. In this case, the IDE uses the `PATH`, `INCLUDE`, and `LIB` environment variables defined for that command line.

Parent topic: Compilation

## See Also

Specifying Path Library and Include Directories
Supported Environment Variables