BUG: fix linux install scripts

Credit to Tom Morse for identifying bug in linux install scripts
where $startdir was missing.

installer/centos/centos7-installer.sh

@@ -22,16 +22,16 @@ cd $startdir && \
     mkdir nrn && \
     cd nrn && \
     git clone https://github.com/neuronsimulator/nrn src && \
-    cd /home/hnn_user/nrn/src && \
+    cd $startdir/nrn/src && \
     ./build.sh && \
     ./configure --with-nrnpython=python3 --with-paranrn --disable-rx3d \
       --without-iv --without-nrnoc-x11 --with-mpi \
-      --prefix=/home/hnn_user/nrn/build && \
+      --prefix=$startdir/nrn/build && \
     make -j4 && \
     make install -j4 && \
     cd src/nrnpython && \
     python3 setup.py install --user && \
-    cd /home/hnn_user/nrn/ && \
+    cd $startdir/nrn/ && \
     rm -rf src && \
     sudo yum clean all
 

installer/centos/native_install.md

@@ -1,18 +1,27 @@
 # HNN native install (CentOS)
 
 The scripts below can be used to install HNN and its prerequisites. However, there is a greater possibility that your base environment will not be compatible with the script and installation might require additional troubleshooting. Thus, we do not recommend this method. For the recommended Docker-based installation, please see the instructions below.
-  - Alternative: [Docker install instructions](README.md)
+
+- Alternative: [Docker install instructions](README.md)
 
 See the scripts in this directory:
-* CentOS 6: [centos6-installer.sh](centos6-installer.sh)
-* CentOS 7: [centos7-installer.sh](centos7-installer.sh)
-  ```
+
+- CentOS 7: [centos7-installer.sh](centos7-installer.sh)
+
+  ```bash
   chmod +x ./centos7-installer.sh
   ./centos7-installer.sh
   ```
 
-# Troubleshooting
+- CentOS 6 (no longer maintained): [centos6-installer.sh](centos6-installer.sh)
+
+  ```bash
+  chmod +x ./centos6-installer.sh
+  ./centos6-installer.sh
+  ```
+
+## Troubleshooting
 
 If you run into other issues with the installation, please [open an issue on our GitHub](https://github.com/jonescompneurolab/hnn/issues). Our team monitors these issues and will be able to suggest possible fixes.
 
-For other HNN software issues, please visit the [HNN bulletin board](https://www.neuron.yale.edu/phpBB/viewforum.php?f=46)
+For other HNN software issues, please visit the [HNN bulletin board](https://www.neuron.yale.edu/phpBB/viewforum.php?f=46)

installer/ubuntu/installer.sh

@@ -20,16 +20,16 @@ cd $startdir && \
     mkdir nrn && \
     cd nrn && \
     git clone https://github.com/neuronsimulator/nrn src && \
-    cd /home/hnn_user/nrn/src && \
+    cd $startdir/nrn/src && \
     ./build.sh && \
     ./configure --with-nrnpython=python3 --with-paranrn --disable-rx3d \
       --without-iv --without-nrnoc-x11 --with-mpi \
-      --prefix=/home/hnn_user/nrn/build && \
+      --prefix=$startdir/nrn/build && \
     make -j4 && \
     make install -j4 && \
     cd src/nrnpython && \
     python3 setup.py install --user && \
-    cd /home/hnn_user/nrn/ && \
+    cd $startdir/nrn/ && \
     rm -rf src && \
     sudo apt-get -y remove --purge bison flex python3-dev zlib1g-dev python && \
     sudo apt-get autoremove -y --purge && \