Voir : https://michauko.org/blog/sftp-chroot-et-pas-de-ssh-bloquer-un-utilisateur-dans-un-repertoire-1099/

Voir aussi :

• Monter un serveur SFTP avec ProFTPd
• SSH SFTP chroot

mkdir -p /chroot/shared/
chown root:nsc /chroot
chmod 750 /chroot
useradd sftpuser -M -d /dev/null -s /sbin/nologin
echo "/mnt/shared/ /chroot/shared/    none _netdev,bind 0 0" >> /etc/fstab

/etc/ssh/sshd_config

# Subsystem sftp /usr/lib/openssh/sftp-server
Subsystem     sftp   internal-sftp

Match User sftpuser
        ChrootDirectory /chroot
        ForceCommand internal-sftp
        AllowTcpForwarding no
        GatewayPorts no
        X11Forwarding no
        PermitTunnel no
        AllowAgentForwarding no
        PermitTTY no

mount /chroot/shared/
systemctl restart sshd
systemctl status sshd

The simplest way is to create some script that would take care of that. Add

Match User test1
  ForceCommand /path/to/your/script.sh

And your script will basically run whatever the user wants, unless it is request for SFTP:

#!/bin/bash
if [[ "$SSH_ORIGINAL_COMMAND" =~ .*sftp-server.* ]]; then
   echo "SFTP not allowed"
   exit 255;
else
   exec "$SSH_ORIGINAL_COMMAND"
fi