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Hello Freesurfer expert, I am brand new to Freesurfer, my apology for the basic question, I kept trying to figure out my mistake in installation for last week and could not find a solution to it.

Here is my output, my problem with subject_DIR keeps changing and recon command is not found. it worked only once with me till I reach example 4 when I had an output that libpng12.so.0 not found.

Thank you for help in advance,

zhbar@DESKTOP-V43QKHC:~$ export FREESURFER_HOME=/usr/local/freesurfer
zhbar@DESKTOP-V43QKHC:~$ source $FREESURFER_HOME/SetUpFreeSurfer.sh
-------- freesurfer-Linux-centos6_x86_64-stable-pub-v6.0.0-2beb96c --------
Setting up environment for FreeSurfer/FS-FAST (and FSL)
FREESURFER_HOME   /usr/local/freesurfer
FSFAST_HOME       /usr/local/freesurfer/fsfast
FSF_OUTPUT_FORMAT nii.gz
SUBJECTS_DIR      /usr/local/freesurfer/subjects
MNI_DIR           /usr/local/freesurfer/mni
zhbar@DESKTOP-V43QKHC:~$ export SUBJECTS_DIR=path to subject data
zhbar@DESKTOP-V43QKHC:~$ sudo cp $FREESURFER_HOME/subjects/sample-001.mgz .
[sudo] password for zhbar:
zhbar@DESKTOP-V43QKHC:~$ mri_convert sample-001.mgz sample-001.nii.gz
mri_convert.bin sample-001.mgz sample-001.nii.gz
$Id: mri_convert.c,v 1.226 2016/02/26 16:15:24 mreuter Exp $
reading from sample-001.mgz...
TR=7.25, TE=3.22, TI=600.00, flip angle=7.00
i_ras = (-0, -1, -0)
j_ras = (-0, 0, -1)
k_ras = (-1, 0, 0)
writing to sample-001.nii.gz...
zhbar@DESKTOP-V43QKHC:~$ export SUBJECTS_DIR=path to subject directory
zhbar@DESKTOP-V43QKHC:~$ recon-all -i sample-001.nii.gz -s bert -all
ERROR: SUBJECTS_DIR path does not exist.
zhbar@DESKTOP-V43QKHC:~$ sudo recon-all -i sample-001.nii.gz -s bert -all
sudo: recon-all: command not found
zhbar@DESKTOP-V43QKHC:~$ source $FREESURFER_HOME/SetUpFreeSurfer.sh
-------- freesurfer-Linux-centos6_x86_64-stable-pub-v6.0.0-2beb96c --------
Setting up environment for FreeSurfer/FS-FAST (and FSL)
WARNING: path does not exist
FREESURFER_HOME   /usr/local/freesurfer
FSFAST_HOME       /usr/local/freesurfer/fsfast
FSF_OUTPUT_FORMAT nii.gz
SUBJECTS_DIR      path
MNI_DIR           /usr/local/freesurfer/mni