systemd-unit-edit 0.1.0

Python bindings for lossless systemd unit file editing

systemd-unit-edit

Python bindings for the systemd-unit-edit Rust library — a lossless parser and editor for systemd unit files.

All whitespace, comments, and formatting are preserved during parsing and modification.

Installation

pip install systemd-unit-edit

Requires Python 3.8+ and a supported platform (Linux x86_64, etc.).

Quick Start

from systemd_unit_edit import SystemdUnit

# Parse from a string
unit = SystemdUnit("""[Unit]
Description=Test Service
After=network.target

[Service]
Type=simple
ExecStart=/usr/bin/test
""")

# Read sections
for section in unit.sections():
    print(section.name())

# Get a specific section
svc = unit.get_section("Service")
print(svc.get("Type"))  # "simple"

# Modify values
svc.set("Type", "forking")

# Add new entries
svc.add("Restart", "on-failure")

# Write back
print(unit.text())  # lossless roundtrip

Loading and Saving Files

# Load from file
unit = SystemdUnit.from_file("/etc/systemd/system/foo.service")

# Load with drop-in overrides merged (e.g. foo.service.d/*.conf)
unit = SystemdUnit.from_file_with_dropins("/etc/systemd/system/foo.service")

# Write to file
unit.write_to_file("/tmp/foo.service")

API Reference

SystemdUnit

The root type representing a parsed systemd unit file.

Method	Description
SystemdUnit(text)	Parse from string. Raises ValueError on syntax errors.
SystemdUnit.from_file(path)	Load from a file. Raises OSError / ValueError.
SystemdUnit.from_file_with_dropins(path)	Load with drop-in .conf files merged.
.sections()	List of all Section objects.
.get_section(name)	Get a Section by name, or None.
.add_section(name)	Append a new empty section.
.text()	Serialize back to string (lossless).
.write_to_file(path)	Write to a file.
.merge_dropin(dropin)	Merge another SystemdUnit as a drop-in.

Section

Represents a section (e.g. [Unit], [Service]).

Method	Description
.name()	Section name string.
.entries()	List of all Entry objects.
.get(key)	First value for a key, or None.
.get_all(key)	All values for a key (for multi-entry keys).
.set(key, value)	Set a value (replaces first occurrence, or adds).
.add(key, value)	Append a new entry (always adds, even if key exists).
.insert_at(index, key, value)	Insert at position among entries.
.insert_before(existing_key, key, value)	Insert before the first entry with existing_key.
.insert_after(existing_key, key, value)	Insert after the first entry with existing_key.
.remove(key)	Remove the first entry with the key.
.remove_all(key)	Remove all entries with the key.
.remove_value(key, value)	Remove a specific value from space-separated entries.
.get_list(key)	Get value as a space-separated list.
.set_list(key, values)	Set a space-separated list value.
.get_bool(key)	Get value as bool (yes/no/true/false/1/0/on/off).
.set_bool(key, value)	Set a boolean value (writes "yes" / "no").

Entry

Represents a key=value entry in a section.

Method	Description
.key()	Key name string.
.value()	Value with line continuations resolved.
.raw_value()	Raw value as it appears in the file.
.set_value(new_value)	Replace the value in place.
.value_as_list()	Value split on whitespace.
.value_as_bool()	Value parsed as boolean.
.is_quoted()	True if value is surrounded by "..." or '...'.
.unquoted_value()	Value with surrounding quotes removed.
.unescape_value()	Value with C-style escapes processed (\n, \t, etc.).
.expand_specifiers(ctx)	Expand %-specifiers using a SpecifierContext.
Entry.escape_value(s)	(static) Escape a string for systemd values.
Entry.format_bool(b)	(static) Format bool as "yes" / "no".

SpecifierContext

Context for expanding systemd %-specifiers.

from systemd_unit_edit import SpecifierContext

# Manual setup
ctx = SpecifierContext()
ctx.set("i", "myinstance")
ctx.expand("/var/lib/%i")  # "/var/lib/myinstance"

# From a unit name (sets %N, %n, %p, %i automatically)
ctx = SpecifierContext.with_unit_name("[e-mail]")
ctx.expand("%p: %i")  # "foo: bar"

Module Functions

Function	Description
parse_timespan(s)	Parse a systemd time span to seconds (float). e.g. "1h 30min" → 5400.0
is_accumulating_directive(key)	True if the directive accumulates values in drop-ins (e.g. Wants, After).

Running Tests

pip install pytest
maturin develop
pytest tests/

License

Apache-2.0