### Systemd Unit File Example

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

A basic systemd service file defining the unit's description, the command to execute, and the target it should be installed under.

```systemd
[Unit]
Description=Example

[Service]
ExecStart=/usr/bin/example

[Install]
WantedBy=multi-user.target
```

--------------------------------

### Example Postinst Maintainer Script

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

Demonstrates the injected shell script fragments in the postinst maintainer script for systemd unit management, including enabling and starting services.

```sh
#!/bin/sh
set -e
# Automatically added by cargo-deb
if [ "$1" = "configure" ] || [ "$1" = "abort-upgrade" ] || [ "$1" = "abort-deconfigure" ] || [ "$1" = "abort-remove" ] ; then
	if deb-systemd-helper debian-installed example.service;
	then
		# This will only remove masks created by d-s-h on package removal.
		deb-systemd-helper unmask example.service >/dev/null || true

		if deb-systemd-helper --quiet was-enabled example.service;
		then
			# Create new symlinks, if any.
			deb-systemd-helper enable example.service >/dev/null || true
		fi
	fi

	# Update the statefile to add new symlinks (if any), which need to be cleaned
	# up on purge. Also remove old symlinks.
	deb-systemd-helper update-state example.service >/dev/null || true
fi
# End automatically added section
# Automatically added by cargo-deb
if [ "$1" = "configure" ] || [ "$1" = "abort-upgrade" ] || [ "$1" = "abort-deconfigure" ] || [ "$1" = "abort-remove" ] ; then
	if [ -d /run/systemd/system ]; then
		systemctl --system daemon-reload >/dev/null || true
		if [ -n "$2" ]; then
			_dh_action=restart
		else
			_dh_action=start
		fi
		deb-systemd-invoke $_dh_action example.service >/dev/null || true
	fi
fi
# End automatically added section
```

--------------------------------

### Rust Main Function Example

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

A simple Rust program that prints 'Hello World!' to standard output.

```rust
fn main() {
  println!("Hello World!");
}
```

--------------------------------

### Install cargo-deb

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Installs the cargo-deb command-line tool. Ensure your Rust toolchain is up-to-date.

```sh
rustup update   # Bookworm's Rust is too outdated, use Trixie or rustup.rs
cargo install cargo-deb
```

--------------------------------

### Install cargo-deb with static LZMA

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Install cargo-deb with the static-lzma feature to resolve 'Undefined reference to `lzma_stream_encoder_mt`' errors.

```sh
cargo install cargo-deb --features=static-lzma
```

--------------------------------

### Example of Merging Assets in Cargo.toml Variants

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Demonstrates how to merge asset lists within different build variants in Cargo.toml using 'append', 'by.dest', and 'by.src' strategies. Explicit paths take precedence over '$auto'.

```toml
# Example parent asset list
[package.metadata.deb]
assets = [
    # binary
    ["target/release/example", "usr/bin/", "755"],
    # assets
    ["assets/*", "var/lib/example", "644"],
    ["target/release/assets/*", "var/lib/example", "644"],
    ["3.txt", "var/lib/example/3.txt", "644"],
    ["3.txt", "var/lib/example/merged.txt", "644"],
]

# Example merging by appending asset list
[package.metadata.deb.variants.mergeappend]
merge-assets.append = [
    ["4.txt", "var/lib/example/appended/4.txt", "644"]
]

# Example merging by `dest` path
[package.metadata.deb.variants.mergedest]
merge-assets.by.dest = [
    ["4.txt", "var/lib/example/merged.txt", "644"]
]

# Example merging by `src` path
[package.metadata.deb.variants.mergesrc]
merge-assets.by.src = [
    ["3.txt", "var/lib/example/merged-2.txt", "644"]
]

# Example merging by appending and by `src` path
[package.metadata.deb.variants.mergeappendandsrc]
merge-assets.append = [
    ["4.txt", "var/lib/example/appended/4.txt", "644"]
]
merge-assets.by.src = [
    ["3.txt", "var/lib/example/merged-2.txt", "644"]
]

```

--------------------------------

### Minimal Systemd Unit Configuration in Cargo.toml

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

Defines a single systemd unit for a package. `enable = false` prevents the unit from being enabled by default on installation.

```toml
[package.metadata.deb]
maintainer-scripts = "debian/"
systemd-units = { enable = false }
```

--------------------------------

### Enable maximum logging

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Increase logging verbosity for troubleshooting using -vv or RUST_LOG=debug.

```sh
cargo deb -vv
```

```sh
RUST_LOG=debug cargo deb -vv
```

--------------------------------

### Specify package metadata crate in workspaces

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

When using workspaces, select the crate for package metadata using -p crate_name or --manifest-path.

```sh
cargo deb -p crate_name
```

```sh
cargo deb --manifest-path=<path/to/Cargo.toml>
```

--------------------------------

### Multiple Systemd Units Configuration in Cargo.toml

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

Specifies multiple systemd unit files for a package. Each entry in the `systemd-units` array defines a unit's name and whether it should be enabled by default.

```toml
[package.metadata.deb]
maintainer-scripts = "debian/"
systemd-units = [
        { unit-name = "unit-one", enable = false },
        { unit-name = "unit-two", enable = false }
    ]
```

--------------------------------

### Custom Cargo.toml Metadata for Debian Packages

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Configure Debian package metadata like maintainer, copyright, license file, extended description, dependencies, section, priority, and assets directly in Cargo.toml.

```toml
[package.metadata.deb]
maintainer = "Michael Aaron Murphy <mmstickman@gmail.com>"
copyright = "2017, Michael Aaron Murphy <mmstickman@gmail.com>"
license-file = ["LICENSE", "4"]
extended-description = """
A simple subcommand for the Cargo package manager for \ building Debian packages from Rust projects."""
depends = "$auto"
section = "utility"
priority = "optional"
assets = [
    # target/release path is special, and gets replaced by cargo-deb with the actual target dir path.
    ["target/release/cargo-deb", "usr/bin/", "755"],
    # both array and object syntaxes are equivalent:
    { source = "README.md", dest = "usr/share/doc/cargo-deb/README", mode = "644"},
]
# assets = ["$auto"] # the default if assets are not specified

```

--------------------------------

### Override deb version and revision

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Customize the version string with --deb-version or the revision suffix with --deb-revision.

```sh
cargo deb --deb-version 1.my-custom-version
```

```sh
cargo deb --deb-revision 1.my-custom-revision
```

--------------------------------

### Invoke cargo-deb with Verbose Output

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

Command to build a Debian package with cargo-deb, showing detailed build information and file processing steps.

```sh
$ cargo-deb -v
```

--------------------------------

### Cross-compile with cargo-deb

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Use the --target flag to specify cross-compilation targets. Multiple targets can be built in parallel. Archives are saved in target/debian/.

```sh
cargo deb --target=i686-unknown-linux-gnu
```

```sh
cargo deb --target=x86_64-unknown-linux-gnu --target=aarch64-unknown-linux-gnu
```

--------------------------------

### Configure Release Profile for Debug Symbols

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Set the debug information level for the release profile in Cargo.toml. Use 'line-tables-only' for minimal debug info or '1' for more detailed information.

```toml
[profile.release]
debug = "line-tables-only"
# or debug = 1 for fatter debug info

```

--------------------------------

### Build Debian Package with cargo-deb

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Builds a Debian package for your Cargo project. The package is created in the target/debian directory by default.

```sh
cargo deb
```

--------------------------------

### Generate Separate Debug Symbol Package

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Use the `--dbgsym` flag to create a separate -dbgsym.ddeb package containing only debug symbols, removing them from the main executables. Requires GNU objcopy.

```sh
cargo deb --dbgsym

```

--------------------------------

### Pass custom cargo build flags

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Use --no-build to prevent cargo-deb from rebuilding the project and pass custom flags to cargo build after --.

```sh
cargo deb -- <cargo build flags>
```

--------------------------------

### Inspect Debian Package Maintainer Scripts

Source: https://github.com/kornelski/cargo-deb/blob/main/systemd.md

Commands to extract maintainer scripts from a generated Debian package and list the extracted files.

```sh
$ dpkg -e target/debian/example_1.2.3_amd64.deb deb_out
$ ls -la deb_out/
```

--------------------------------

### Separate Debug Symbols in the Same Package

Source: https://github.com/kornelski/cargo-deb/blob/main/README.md

Use `--separate-debug-symbols` to place debug symbols in separate files within the package, and optionally `--compress-debug-symbols` to compress them. Requires GNU objcopy.

```sh
cargo deb --separate-debug-symbols --compress-debug-symbols

```

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