Need help with changing terminal to csh for linux

[prajwalg]

Hello,
I am working with a software called FreeSurfer: FreeSurferWiki - Free Surfer Wiki
I have successfully installed it on the repository, but am unable to run some of its commands. From what I understood, the linux shell is a bash shell, and I need to have a tcsh shell, as when I run the command:
$ recon-all -s 1514935 -i /project/prajwalg/subjects/1514935/1514935-20050520_T1.nii.gz -all
i get error:
bash: /home1/prajwalg/freesurfer/bin/recon-all: /bin/tcsh: bad interpreter: No such file or directory

Because when I wanted to change the shell to a csh shell using the $ chsh -s /bin/csh command, I got output: chsh: “/bin/csh” does not exist

So i wanted to to install this now, but for that, when i run sudo apt-get install csh, i get output that bash: sudo: command not found.
Now even to install sudo, i run $ su, but it asks for a password now, which I dont have.

So is there any way to change to a csh shell or at least install tcsh, because even installing it will make the commands run.

Thanks!

[dstrong]

Try loading a tcsh software module. For example:

module purge
module load gcc/11.3.0
module load tcsh/6.24.00

[prajwalg]

thanks, I ran these commands
then I ran $ cat /etc/shells to see which shells are installed on the system, got the following output:

/bin/sh
/bin/bash
/usr/bin/sh
/usr/bin/bash

then I ran this to change the shell:
$ chsh -s /bin/sh

got the following outputs:

Changing shell for prajwalg.
chsh: Shell not changed.

[dstrong]

It’s not possible to use chsh on the system to change the default shell. To use tcsh, first load the module and then run tcsh to open an interactive tcsh session.