m4:tldr:49d0c

m4: Define a macro before processing files.

$ m4 -D${macro_name}=${macro_value} ${filename}

try on your machine

This command is using the m4 macro processing tool with specific options and arguments.

m4 is a program used for preprocessing text files. It interprets and expands macros in a file that is processed.
-D${macro_name}=${macro_value} is an option that defines a macro with a specific name and its corresponding value. The ${macro_name} and ${macro_value} are placeholders that should be replaced with actual values. This option allows you to set a macro that can be used in the file being processed by m4.
${filename} is the name of the file that will be processed by m4. It is the input file where macros will be expanded and text will be processed.

So, overall, this command tells m4 to process the specified file (${filename}), while defining a macro with a name ${macro_name} and value ${macro_value}. The macro can then be used and expanded within the file during processing.

This explanation was created by an AI. In most cases those are correct. But please always be careful and never run a command you are not sure if it is safe.

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