Installing gfortran on CentOS 7

GFortran is the GNU Fortran compiler from the GCC toolchain. It’s essential for scientific computing, numerical simulations, and legacy Fortran code maintenance.

Quick Install

On modern RHEL-based systems (RHEL 9+, Rocky Linux, AlmaLinux, CentOS Stream):

sudo dnf install gcc-gfortran

On CentOS 7 (EOL since June 2024), the older yum package manager still works:

sudo yum install gcc-gfortran

However, CentOS 7 is no longer supported. If you’re still running it, plan a migration to Rocky Linux or AlmaLinux — they provide binary compatibility and continued security updates.

Verify Installation

After installation, confirm GFortran is working:

gfortran --version

You should see output like:

GNU Fortran (GCC) 12.3.1 20230816 (Red Hat 12.3.1-2)

Compile a Simple Program

Test with a basic Fortran program:

program hello
  print *, 'Hello from Fortran'
end program hello

Save as hello.f90, then compile:

gfortran -o hello hello.f90
./hello

Installing Full Development Tools

For more comprehensive Fortran development, install the entire gcc-toolset:

sudo dnf install gcc gcc-c++ gcc-gfortran make

On older systems, the “Development Tools” group provides these:

sudo yum groupinstall "Development Tools"

HPC Environments and Modern Workflows

For scientific computing with multiple compiler versions, MPI libraries, or BLAS/LAPACK dependencies, use a package manager designed for HPC:

Spack — manages complex dependency trees and multiple compiler toolchains:

git clone https://github.com/spack/spack.git
cd spack
. share/spack/setup-env.sh
spack install gcc@13.2.0
spack install openmpi %gcc@13.2.0

EasyBuild — provides pre-configured recipes for scientific software:

pip install easybuild
eb GCC-13.2.0.eb -r
eb OpenMPI-4.1.5-GCC-13.2.0.eb -r

Conda/Mamba is another lightweight option for isolated environments:

mamba install -c conda-forge gfortran openmpi

Troubleshooting

Command not found: GFortran isn’t in your PATH. Verify installation with which gfortran. If nothing returns, reinstall: sudo dnf reinstall gcc-gfortran.

Version mismatch: Multiple GCC versions may be installed. Use update-alternatives to switch:

sudo update-alternatives --install /usr/bin/gfortran gfortran /usr/bin/gfortran-12 100
sudo update-alternatives --install /usr/bin/gfortran gfortran /usr/bin/gfortran-13 200
sudo update-alternatives --config gfortran

Missing dependencies for compilation: Some Fortran packages need BLAS/LAPACK. Install them with:

sudo dnf install blas-devel lapack-devel

Common Compilation Flags

When building Fortran code, you’ll often use:

• -O2 or -O3 — optimization levels
• -Wall — enable warnings
• -g — debug symbols
• -fcheck=all — runtime bounds checking
• -fopenmp — OpenMP parallelization support

Example:

gfortran -O3 -Wall -fopenmp -o program program.f90

Troubleshooting Common Issues

When encountering problems on Linux systems, follow a systematic approach. Check system logs first using journalctl for systemd-based distributions. Verify service status with systemctl before attempting restarts. For network issues, use ip addr and ss -tulpn to diagnose connectivity problems.

Package management issues often stem from stale caches. Run dnf clean all on Fedora or apt clean on Ubuntu before retrying failed installations. If a package has unmet dependencies, try resolving them with dnf autoremove or apt autoremove.

Related System Commands

These commands are frequently used alongside the tools discussed in this article:

• systemctl status service-name – Check if a service is running
• journalctl -u service-name -f – Follow service logs in real time
• rpm -qi package-name – Query installed package information
• dnf history – View package transaction history
• top or htop – Monitor system resource usage

Quick Verification

After applying the changes described above, verify that everything works as expected. Run the relevant commands to confirm the new configuration is active. Check system logs for any errors or warnings that might indicate problems. If something does not work as expected, review the steps carefully and consult the official documentation for your specific version.