External Email - Use Caution        


SyntaxError: Missing parentheses in call to 'print'. Did you mean print('ERROR: atleast 1 subject must be provided')?
It does not look like you are running a python 2.X.  That may be because only python3 is installed by default.

$ which python
$ which python2
$ which python3
/bin/python3

… if you need to install python2, you can do it with ...

$ sudo apt update
$ sudo apt install python2

$ which python2
/bin/python2
$ python2 --version
Python 2.7.18

One way or another you need “python” to report it is a 2.X version *after* you set FREESURFER_HOME and source the freesurfer setup script.  To force “python” to run as “python2” you can try using an alias,

$ alias python=python2
$ python --version
Python 2.7.18

Similarly, if you needed python to run as python3 you could reset the alias to use =python3 instead.

For the error,
 print 'ERROR: subjects are not specified (use --subjects SUBJECTS)’
I would check the subjects you are listing as argument can be found as directories under what SUBJECTS_DIR is currently set to.

- R.