A Python function used to print the command lines as they are executed (assuming command printing is not disabled by the -q or -s options or their equivalents). The function should take four arguments: s, the command being executed (a string), target, the target being built (file node, list, or string name(s)), source, the source(s) used (file node, list, or string name(s)), and env, the environment being used. The function must do the printing itself. The default implementation, used if this variable is not set or is None, is: def print_cmd_line(s, target, source, env): sys.stdout.write(s + "\n") Here's an example of a more interesting function: def print_cmd_line(s, target, source, env): sys.stdout.write("Building %s -> %s...\n" % (' and '.join([str(x) for x in source]), ' and '.join([str(x) for x in target]))) env=Environment(PRINT_CMD_LINE_FUNC=print_cmd_line) env.Program('foo', 'foo.c') This just prints "Building targetname from sourcename..." instead of the actual commands. Such a function could also log the actual commands to a log file, for example.

A command interpreter function that will be called to execute command line strings. The function must expect the following arguments: def spawn(shell, escape, cmd, args, env): sh is a string naming the shell program to use. escape is a function that can be called to escape shell special characters in the command line. cmd is the path to the command to be executed. args is the arguments to the command. env is a dictionary of the environment variables in which the command should be executed.