1# $NetBSD: comment.mk,v 1.5 2022/05/08 06:51:27 rillig Exp $ 2# 3# Demonstrate how comments are written in makefiles. 4 5# This is a comment. 6 7#\ 8This is a multiline comment. 9 10# Another multiline comment \ 11that \ 12goes \ 13on and on. 14 15 # Comments can be indented with spaces, but that is rather unusual. 16 17 # Comments can be indented with a tab. 18 # Since parse.c 1.127 from 2007-01-01, these are not shell commands, 19 # they are just makefile comments. Before that commit, these comments 20 # triggered the error message "Unassociated shell command". 21 22.if 1 # There can be comments after conditions. 23.endif # And after the closing directive. 24 25VAR= # This comment makes the variable value empty. 26 # ParseRawLine removes any whitespace before the 27 # comment. 28.if ${VAR} != "" 29. error 30.endif 31 32# The comment does not need to start at the beginning of a word (as in the 33# shell), it can start anywhere. 34VAR=# defined but empty 35 36# The space before the comment is always trimmed. 37VAR= value 38.if ${VAR} != "value" 39. error 40.endif 41 42# This comment ends with 2 backslashes. An even number of backslashes does 43# not count as a line continuation, therefore the variable assignment that 44# follows is actively interpreted. \\ 45VAR= not part of the comment 46.if ${VAR} != "not part of the comment" 47. error 48.endif 49 50# To escape a comment sign, precede it with a backslash. 51VAR= \# # Both in the assignment. 52.if ${VAR} != "\#" # And in the comparison. 53. error 54.endif 55 56# Since 2012-03-24 the variable modifier :[#] does not need to be escaped. 57# To keep the parsing code simple, any "[#" does not start a comment, even 58# outside of a variable expression. 59WORDS= ${VAR:[#]} [# 60.if ${WORDS} != "1 [#" 61. error 62.endif 63 64# An odd number of backslashes makes a line continuation, \\\ 65no matter if it is 3 or 5 \\\\\ 66or 9 backslashes. \\\\\\\\\ 67This is the last line of the comment. 68VAR= no comment anymore 69.if ${VAR} != "no comment anymore" 70. error 71.endif 72 73all: 74# In the commands associated with a target, the '#' does not start a makefile 75# comment. The '#' is just passed to the shell, like any ordinary character. 76 echo This is a shell comment: # comment 77# If the '#' were to start a makefile comment, the following shell command 78# would have unbalanced quotes. 79 echo This is not a shell comment: '# comment' 80 @echo A shell comment can#not start in the middle of a word. 81