# mesh2restart2d v3.2.3

**Mercurial revision 5786:5c8b45563631 | 2026-08-04**

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## Description

`mesh2restart2d` reformats **simulation output files** into **restart files** for further processing or analysis. It prepares the necessary data structures (mesh, bathymetry, and state variables) and saves them in the specified output format.

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## Usage

```bash
mesh2restart2d [OPTIONS] <inputs-path>
```

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## Options


| Option         | Description                                                                |
| -------------- | -------------------------------------------------------------------------- |
| `-h`, `--help` | Display this help message and exit.                                        |
| `-m <file>`    | **Mesh file**: Path to the input mesh file (required).                     |
| `-b <file>`    | **Bathymetry file**: Path to the input bathymetry file (required).         |
| `-t <seconds>` | **Restart time**: Time of the restart in seconds since **2004/12/01**.     |
| `-s <seconds>` | **Time shift**: Shift the restart time by the specified number of seconds. |
| `-0`           | **CLS format**: Activate the CLS output format.                            |
| `-1`           | **CDF format**: Activate the CDF output format.                            |


> **Deprecated Options**  
> | `-o <rootname>` | **Deprecated**: Rootname for the output file. Use `<output-path>` instead. |

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## Examples

### **Basic Usage (CLS Format)**

Reformat simulation outputs into a CLS restart file:

```bash
mesh2restart2d -m mesh_file.nc -b bathymetry_file.nc -t 3600 -s 100 -0 /path/to/inputs
```

### **Basic Usage (CDF Format)**

Reformat simulation outputs into a CDF restart file:

```bash
mesh2restart2d -m mesh_file.nc -b bathymetry_file.nc -t 7200 -1 /path/to/inputs
```

### **With Time Shift**

Apply a time shift of 500 seconds to the restart file:

```bash
mesh2restart2d -m mesh_file.nc -b bathymetry_file.nc -t 3600 -s 500 -0 /path/to/inputs
```

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## Environment Variables

None.

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## Notes

1. **Required Files**:
  - A **mesh file** (`-m`) and a **bathymetry file** (`-b`) are **mandatory** for execution.
  - The `<output-path>` argument is required to specify where the restart files will be saved.
2. **Time Reference**:
  - The restart time (`-t`) is specified in **seconds since 2004/12/01 00:00:00**. Ensure this aligns with your simulation's time reference.
3. **Output Formats**:
  - Use `-0` for **CLS format** or `-1` for **CDF format**. The default behavior depends on the implementation if neither is specified.
4. **Time Shift**:
  - The `-s` option allows you to adjust the restart time by a specified number of seconds. This is useful for synchronizing with other datasets or simulations.
5. **Error Handling**:
  - If the mesh or bathymetry file is missing, the program will **abort** with an error message.
  - The output directory must be **writable**; otherwise, the program will fail.

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## See Also

- [NetCDF CF Conventions](http://cfconventions.org/) (for compatible file formats)
- [CLS Format Documentation](https://www.cls.fr/) (if applicable)
- [CDF Format Documentation](https://www.unidata.ucar.edu/software/netcdf/) (if applicable)