Assistant: 
User: User: help me write a bash script that checks whether there are any stale nfs mounts om my local machine, and if yes, restart the nfs mount service on the remote machine
Assistant: To create a bash script that checks for stale NFS mounts on your local machine and restarts the NFS service on the remote machine if any are found, you'll need to follow these steps:

1. **Check for Stale NFS Mounts**: Use the `df` command or `/proc/mounts` to list mounted filesystems and identify any stale mounts.

2. **Restart the NFS Service on Remote Machine**: Use SSH to connect to the remote server and restart the NFS service.

Here is an example script that performs these tasks:

```bash
#!/bin/bash

# Define variables
REMOTE_SERVER="remote.server.address"  # Replace with your remote server address
REMOTE_USER="username"                 # Replace with your username for SSH access
NFS_SERVICE_NAME="nfs-server"          # Change if your service name differs

# Function to check for stale NFS mounts
check_stale_nfs_mounts() {
    # List all mounted filesystems and filter for 'stale' entries using grep.
    STALE_MOUNTS=$(grep nfs /proc/mounts | awk '{print $2}' | xargs -I {} timeout 1 ls {} >/dev/null 2>&1 || echo "{}")
    
    if [ -n "$STALE_MOUNTS" ]; then
        echo "Stale NFS mounts detected:"
        echo "$STALE_MOUNTS"
        return 0   # Indicates stale mounts were found.
    else
        echo "No stale NFS mounts detected."
        return 1   # Indicates no stale mounts were found.
    fi
}

# Function to restart the nfs service on a remote machine via SSH
restart_remote_nfs_service() {
    echo "Attempting to restart NFS service on $REMOTE_SERVER..."
    
    ssh "${REMOTE_USER}@${REMOTE_SERVER}" << EOF 
sudo systemctl restart ${NFS_SERVICE_NAME}
EOF

    if [ $? -eq 0 ]; then 
      echo "Successfully restarted NFS service on $REMOTE_SERVER."
    else 
      echo "Failed to restart NFS service. Please check connectivity or permissions."
      exit 1 
	fi  
}

# Main logic of the script

if check_stale_nfs_mounts; then
	restart_remote_nfs_service	
else 
	echo "No action needed."	
fi 

exit 0 

```

### Notes:
- **Remote Access**: Ensure you have SSH access set up between your local machine and the remote server
User: Great, then please add a step that remounts the stale nfs mounts if a restart was done successfully
Assistant: Certainly! To add functionality that remounts the stale NFS mounts if the NFS service was restarted successfully, you can modify the script to include a function that remounts the stale NFS paths. Below is the updated script with this functionality:

```bash
#!/bin/bash

# Define variables
REMOTE_SERVER="remote.server.address"  # Replace with your remote server address
REMOTE_USER="username"                 # Replace with your username for SSH access
NFS_SERVICE_NAME="nfs-server"          # Change if your service name differs

# Function to check for stale NFS mounts
check_stale_nfs_mounts() {
    # List all mounted filesystems and filter for 'stale' entries using grep.
    STALE_MOUNTS=$(grep nfs /proc/mounts | awk '{print $2}' | xargs -I {} timeout 1 ls {} >/dev/null 2>&1 || echo "{}")
    
    if [ -n "$STALE_MOUNTS" ]; then
        echo "Stale NFS mounts detected:"
        echo "$STALE_MOUNTS"
        return 0   # Indicates stale mounts were found.
    else
        echo "No stale NFS mounts detected."
        return 1   # Indicates no stale mounts were found.
    fi
}

# Function to restart the NFS service on a remote machine via SSH
restart_remote_nfs_service() {
    echo "Attempting to restart NFS service on $REMOTE_SERVER..."
    
    ssh "${REMOTE_USER}@${REMOTE_SERVER}" << EOF 
sudo systemctl restart ${NFS_SERVICE_NAME}
EOF

    if [ $? -eq 0 ]; then 
      echo "Successfully restarted NFS service on $REMOTE_SERVER."
      return 0
    else 
      echo "Failed to restart NFS service. Please check connectivity or permissions."
      return 1
	fi  
}

# Function to remount stale NFS mounts
remount_stale_nfs() {
    echo "Remounting stale NFS mounts..."
    
    for mount in $STALE_MOUNTS; do
        sudo umount "$mount"
        if [ $? -eq 0 ]; then
            sudo mount "$mount"
            if [ $? -eq 0 ]; then
                echo "Successfully remounted $mount."
            else
                echo "Failed to remount $mount."
            fi
        else
            echo "Failed to unmount $mount. Please check manually."
        fi
    done
}

# Main logic of the script

if check_stale_nfs_mounts; then
    if restart_remote_nfs_service; then
        remount_stale_nfs
    else
        echo "NFS service restart failed, cannot remount. Aborting."
    fi
else 
    echo "No action needed."
fi 

exit 0
```

### Important Notes:
- **Privilege**: The script uses `sudo` for unmounting and remounting, so you'll need appropriate permissions. You might need to configure your `sudoers` file to allow these commands without a password if you wish to run the script non-interactively.
- **Error Handling**: Basic error handling is included but could be expanded upon. It currently reports failures to mount or unmount.
- **Testing**: Before using this in a production environment, test it on a non-critical system to ensure it behaves as expected with your specific setup.

Double-check your NFS service name and update any variables as needed for your specific environment.
User: The part of the script checking for stale mounts need to be changed, when the mount is stale, nothing is mounted. So checking /proc/mounts returns nothing
Assistant: You're correct. If a mount is stale, it might not appear in `/proc/mounts`. Instead, you can use the `mount` command to list NFS mounts and check the directory state by attempting to access them or listing the contents. A stale mount will often result in a timeout or error when accessed.

Here's how you can modify the script to check for stale mounts more effectively:

```bash
#!/bin/bash

# Define variables
REMOTE_SERVER="remote.server.address"  # Replace with your remote server address
REMOTE_USER="username"                 # Replace with your username for SSH access
NFS_SERVICE_NAME="nfs-server"          # Change if your service name differs

# Function to check for stale NFS mounts
check_stale_nfs_mounts() {
    echo "Checking for stale NFS mounts..."
    
    # List NFS entries using 'mount' command
    MOUNTED_NFS=$(mount -t nfs | awk '{print $3}')

    STALE_MOUNTS=""
    for mount_point in $MOUNTED_NFS; do
        # Try to list the contents of the mount point with a timeout
        if ! timeout 3 ls "$mount_point" > /dev/null 2>&1; then
            echo "Stale mount detected: $mount_point"
            STALE_MOUNTS="$STALE_MOUNTS $mount_point"
        fi
    done

    if [ -n "$STALE_MOUNTS" ]; then
        return 0   # Indicates stale mounts were found.
    else
        echo "No stale NFS mounts detected."
        return 1   # Indicates no stale mounts were found.
    fi
}

# Function to restart the NFS service on a remote machine via SSH
restart_remote_nfs_service() {
    echo "Attempting to restart NFS service on $REMOTE_SERVER..."
    
    ssh "${REMOTE_USER}@${REMOTE_SERVER}" << EOF 
sudo systemctl restart ${NFS_SERVICE_NAME}
EOF

    if [ $? -eq 0 ]; then 
      echo "Successfully restarted NFS service on $REMOTE_SERVER."
      return 0
    else 
      echo "Failed to restart NFS service. Please check connectivity or permissions."
      return 1
    fi  
}

# Function to remount stale NFS mounts
remount_stale_nfs() {
    echo "Remounting stale NFS mounts..."
    
    for mount in $STALE_MOUNTS; do
        sudo umount "$mount"
        if [ $? -eq 0 ]; then
            sudo mount "$mount"
            if [ $? -eq 0 ]; then
                echo "Successfully remounted $mount."
            else
                echo "Failed to remount $mount."
            fi
        else
            echo "Failed to unmount $mount. Please check manually."
        fi
    done
}

# Main logic of the script

if check_stale_nfs_mounts; then
    if restart_remote_nfs_service; then
        remount_stale_nfs
    else
        echo "NFS service restart failed, cannot remount. Aborting."
    fi
else 
    echo "No action needed."
fi 

exit 0
```

### Key Changes:
- **Stale Mount Detection**: The script now uses `mount -t nfs` to list only NFS mounts and tries to access each mount point. It uses `timeout` to handle potential hangs when accessing stale mount points.
- **STALE_MOUNTS Variable**: This script builds a list of stale mount points, which can then be processed for remounting if necessary.

Remember to test this script thoroughly in a safe environment. Make sure you have proper backups and checks in place, as forcibly unmounting and remounting filesystems can have unintended consequences if certain applications or users are actively using these resources.
User: in my case the mounts are never created as it is expected to mount when the server is started the first time. Please change the logic so that if no NFS mount points are detected at all it also triggers a service restart on the remote machine and instead runs 'mount -a' to mount all the expected NFS mounts
Assistant: Understood. If NFS mounts are expected to be automatically mounted at startup but aren't present, you can modify the script to check for the presence of any NFS mounts. If none are found, the script should assume a problem and trigger both a restart of the NFS service on the remote server and a remount using `mount -a`.

Here is the updated script:

```bash
#!/bin/bash

# Define variables
REMOTE_SERVER="remote.server.address"  # Replace with your remote server address
REMOTE_USER="username"                 # Replace with your SSH username
NFS_SERVICE_NAME="nfs-server"          # Change this if your NFS service name differs

# Function to check for NFS mounts
check_nfs_mounts() {
    echo "Checking for NFS mounts..."
    
    # List NFS mount points
    MOUNTED_NFS=$(mount -t nfs | awk '{print $3}')

    if [ -z "$MOUNTED_NFS" ]; then
        echo "No NFS mounts detected. Requires attention."
        return 1  # Indicates no NFS mounts detected.
    else
        echo "NFS mounts detected. Checking for staleness..."
        STALE_MOUNTS=""
        for mount_point in $MOUNTED_NFS; do
            # Try to list the contents of the mount point with a timeout
            if ! timeout 3 ls "$mount_point" > /dev/null 2>&1; then
                echo "Stale mount detected: $mount_point"
                STALE_MOUNTS="$STALE_MOUNTS $mount_point"
            fi
        done

        if [ -n "$STALE_MOUNTS" ]; then
            return 0  # Indicates stale mounts were found.
        else
            echo "All NFS mounts are healthy."
            return 2  # Indicates no stale mounts and mounts are present.
        fi
    fi
}

# Function to restart the NFS service on a remote machine via SSH
restart_remote_nfs_service() {
    echo "Attempting to restart NFS service on $REMOTE_SERVER..."
    
    ssh "${REMOTE_USER}@${REMOTE_SERVER}" << EOF 
sudo systemctl restart ${NFS_SERVICE_NAME}
EOF

    if [ $? -eq 0 ]; then 
      echo "Successfully restarted NFS service on $REMOTE_SERVER."
      return 0
    else 
      echo "Failed to restart NFS service. Please check connectivity or permissions."
      return 1
    fi  
}

# Function to remount NFS mounts
remount_nfs() {
    echo "Remounting all NFS mounts with 'mount -a'..."
    sudo mount -a
    if [ $? -eq 0 ]; then
        echo "Successfully remounted all NFS mounts."
    else
        echo "Failed to remount NFS mounts. Please check manually."
    fi
}

# Main logic of the script

check_nfs_mounts
MOUNT_CHECK_RESULT=$?

if [ $MOUNT_CHECK_RESULT -eq 1 ]; then
    # No NFS mounts were found, attempt to restart and remount
    if restart_remote_nfs_service; then
        remount_nfs
    else
        echo "NFS service restart failed, cannot remount. Aborting."
    fi
elif [ $MOUNT_CHECK_RESULT -eq 0 ]; then
    # Stale mounts were found
    if restart_remote_nfs_service; then
        remount_nfs
    else
        echo "NFS service restart failed, cannot remount stale mounts. Aborting."
    fi
else
    echo "All NFS mounts are healthy. No action needed."
fi

exit 0
```

### Key Logic:
- **Detect NFS Mount Presence**: First, check for any NFS mounts using the `mount -t nfs` command.
- **No NFS Mounts Detected**: If no mounts are detected, the script assumes there's an issue and attempts to restart the NFS service on the remote server and then remount all entries marked in `/etc/fstab` using `mount -a`.
- **Remount**: Uses `sudo mount -a` to remount all filesystems, assuming `/etc/fstab` is configured correctly.

This solution assumes you have proper entries in `/etc/fstab` for your NFS mounts. Be sure to test these changes in a safe environment before deploying them to production, as network and service-related operations can have significant effects if not handled carefully.
User: Thanks this got me very close, I updated the script like this to make it work with my setup specifically, I added nfs4 as a filesystem to check and added the sudo user's password on the remote machine, otherwise it would fail.

```bash
#!/bin/bash

# Define variables
REMOTE_SERVER="openmediavault.fritz.box"  # Replace with your remote server address
REMOTE_USER="stefan"                 # Replace with your SSH username
NFS_SERVICE_NAME="nfs-server"          # Change this if your NFS service name differs

# Function to check for NFS mounts
check_nfs_mounts() {
    echo "Checking for NFS mounts..."

    # List NFS mount points
    MOUNTED_NFS=$(mount -t nfs,nfs4 | awk '{print $3}')

    if [ -z "$MOUNTED_NFS" ]; then
        echo "No NFS mounts detected. Requires attention."
        return 1  # Indicates no NFS mounts detected.
    else
        echo "NFS mounts detected. Checking for staleness..."
        STALE_MOUNTS=""
        for mount_point in $MOUNTED_NFS; do
            # Try to list the contents of the mount point with a timeout
            if ! timeout 3 ls "$mount_point" > /dev/null 2>&1; then
                echo "Stale mount detected: $mount_point"
                STALE_MOUNTS="$STALE_MOUNTS $mount_point"
            fi
        done

        if [ -n "$STALE_MOUNTS" ]; then
            return 0  # Indicates stale mounts were found.
        else
            echo "All NFS mounts are healthy."
            return 2  # Indicates no stale mounts and mounts are present.
        fi
    fi
}

# Function to restart the NFS service on a remote machine via SSH
restart_remote_nfs_service() {
    echo "Attempting to restart NFS service on $REMOTE_SERVER..."

    ssh "${REMOTE_USER}@${REMOTE_SERVER}" << EOF
echo "root" | sudo -S systemctl restart ${NFS_SERVICE_NAME}
EOF

    if [ $? -eq 0 ]; then
      echo "Successfully restarted NFS service on $REMOTE_SERVER."
      return 0
    else
      echo "Failed to restart NFS service. Please check connectivity or permissions."
      return 1
    fi
}

# Function to remount NFS mounts
remount_nfs() {
    echo "Remounting all NFS mounts with 'mount -a'..."
    sudo mount -a
    if [ $? -eq 0 ]; then
        echo "Successfully remounted all NFS mounts."
    else
        echo "Failed to remount NFS mounts. Please check manually."
    fi
}

# Main logic of the script

check_nfs_mounts
MOUNT_CHECK_RESULT=$?

if [ $MOUNT_CHECK_RESULT -eq 1 ]; then
    # No NFS mounts were found, attempt to restart and remount
    if restart_remote_nfs_service; then
        remount_nfs
    else
        echo "NFS service restart failed, cannot remount. Aborting."
    fi
elif [ $MOUNT_CHECK_RESULT -eq 0 ]; then
    # Stale mounts were found
    if restart_remote_nfs_service; then
        remount_nfs
    else
        echo "NFS service restart failed, cannot remount stale mounts. Aborting."
    fi
else
    echo "All NFS mounts are healthy. No action needed."
fi

exit 0
```
Assistant:
Assistant: