Pragmatic comments are similar to usual single-line comments, except that they cause some changes in the way the configuration is parsed. Pragmatic comments begin with a ‘#’ sign and end with the next physical newline character.
Include the contents of the file file. There are three possible use cases.
If file is an absolute file name, the named file is included. An error message will be issued if it does not exist.
If file contains wildcard characters (‘*’, ‘[’, ‘]’ or ‘?’), it is interpreted as shell globbing pattern and all files matching that pattern are included, in lexicographical order. If no files match the pattern, the statement is silently ignored.
Otherwise, the form with angle brackets searches for file in the include search path, while the second one looks for it in the current working directory first, and, if not found there, in the include search path. If the file is not found, an error message will be issued.
The default include search path is:
where prefix is the installation prefix.
#include, except that, if the file has already
been included, it will not be included again.
#line num "file"
This line causes the parser to believe, for purposes of error diagnostics, that the line number of the next source line is given by num and the current input file is named by file. If the latter is absent, the remembered file name does not change.
# num "file"
This is a special form of
#line statement, understood for
compatibility with the C preprocessor.