c99:tldr:a8027

The command "c99 -c ${file-c}" is invoking the c99 compiler to compile a C source file into an object file.

Here's a breakdown of the command:

• "c99": This is the name of the C compiler being used. It is assumed to be the C99 version, hence the name.
• "-c": This flag instructs the compiler to only perform the compilation step and not the linking step. It generates an object file (.o) as output.
• "${file-c}": This is a variable substitution or placeholder typically used in build systems. It indicates that the value of the variable "file" should be used at this position in the command. If the variable "file" is not defined or its value is empty, the option "-c" will be used instead.

Overall, this command compiles a C source file into an object file using the c99 compiler, where the name of the source file is specified by the "file" variable.