How to use the command systemd-escape (with examples)

Systemd is a system and service manager for Linux operating systems. The systemd-escape command is a utility that allows users to escape strings for usage in systemd unit names. This can be useful when creating or managing systemd units, where certain characters or strings need to be properly escaped.

Use case 1: Escape the given text

Code:

systemd-escape "hello_world"

Motivation:

Escaping the given text is useful when we want to use it in a systemd unit name, but the text contains characters that are not allowed in unit names. By using systemd-escape, we can ensure that the text is properly escaped and can be safely used in unit names.

Explanation:

The command systemd-escape is followed by the text that needs to be escaped. In this use case, we want to escape the text “hello_world”.

Example output:

hello\x2dworld

Use case 2: Reverse the escaping process

Code:

systemd-escape --unescape "hello\x2dworld"

Motivation:

Sometimes, we may need to reverse the escaping process in order to retrieve the original text. This could be useful when we want to reference the original text that was used in a systemd unit name.

Explanation:

The --unescape flag is used to reverse the escaping process. In this use case, we want to reverse the escaping of the text “hello\x2dworld”.

Example output:

hello_world

Use case 3: Treat the given text as a path

Code:

systemd-escape --path "/var/log/messages"

Motivation:

In some cases, the given text may be a path that needs to be used in a systemd unit name. By using the --path flag, we can treat the given text as a path and properly escape it for usage in a unit name.

Explanation:

The --path flag is used to indicate that the given text should be treated as a path. In this use case, we want to treat the text “/var/log/messages” as a path.

Example output:

var-log-messages

Use case 4: Append the given suffix to the escaped text

Code:

systemd-escape --suffix ".service" "example_service"

Motivation:

Appending a suffix to the escaped text can be useful when we want to create a systemd unit name that follows a specific naming convention. This makes it easier to identify the purpose or type of the unit.

Explanation:

The --suffix flag is used to specify the suffix that should be appended to the escaped text. In this use case, we want to append the suffix “.service” to the escaped text “example_service”.

Example output:

example_service.service

Use case 5: Use a template and inject the escaped text

Code:

systemd-escape --template "myapp@.service" "my_instance"

Motivation:

Sometimes, we may need to use a template that includes a placeholder for the escaped text. This can be useful when we want to create multiple systemd units that follow a similar naming convention but have different values for a specific part of the name.

Explanation:

The --template flag is used to specify the template that should be used, with a placeholder (%) for the escaped text. In this use case, we want to use the template “myapp@.service” and inject the escaped text “my_instance”.

Example output:

myapp@my_instance.service

Conclusion:

The systemd-escape command provides a convenient way to escape strings for usage in systemd unit names. By using different flags and arguments, users can modify the escaping process and create unit names that follow specific naming conventions. Whether it’s escaping text, reversing the escaping process, treating text as a path, appending suffixes, or using templates, systemd-escape offers flexibility and reliability when working with systemd units.