comment.mk revision 1.5
1 1.5 rillig # $NetBSD: comment.mk,v 1.5 2022/05/08 06:51:27 rillig Exp $ 2 1.2 rillig # 3 1.2 rillig # Demonstrate how comments are written in makefiles. 4 1.2 rillig 5 1.2 rillig # This is a comment. 6 1.1 apb 7 1.1 apb #\ 8 1.2 rillig This is a multiline comment. 9 1.2 rillig 10 1.2 rillig # Another multiline comment \ 11 1.2 rillig that \ 12 1.2 rillig goes \ 13 1.2 rillig on and on. 14 1.2 rillig 15 1.3 rillig # Comments can be indented with spaces, but that is rather unusual. 16 1.1 apb 17 1.2 rillig # Comments can be indented with a tab. 18 1.4 rillig # Since parse.c 1.127 from 2007-01-01, these are not shell commands, 19 1.4 rillig # they are just makefile comments. Before that commit, these comments 20 1.4 rillig # triggered the error message "Unassociated shell command". 21 1.1 apb 22 1.2 rillig .if 1 # There can be comments after conditions. 23 1.2 rillig .endif # And after the closing directive. 24 1.2 rillig 25 1.2 rillig VAR= # This comment makes the variable value empty. 26 1.5 rillig # ParseRawLine removes any whitespace before the 27 1.3 rillig # comment. 28 1.2 rillig .if ${VAR} != "" 29 1.2 rillig . error 30 1.2 rillig .endif 31 1.1 apb 32 1.2 rillig # The comment does not need to start at the beginning of a word (as in the 33 1.2 rillig # shell), it can start anywhere. 34 1.2 rillig VAR=# defined but empty 35 1.2 rillig 36 1.2 rillig # The space before the comment is always trimmed. 37 1.2 rillig VAR= value 38 1.2 rillig .if ${VAR} != "value" 39 1.2 rillig . error 40 1.2 rillig .endif 41 1.1 apb 42 1.3 rillig # This comment ends with 2 backslashes. An even number of backslashes does 43 1.3 rillig # not count as a line continuation, therefore the variable assignment that 44 1.3 rillig # follows is actively interpreted. \\ 45 1.2 rillig VAR= not part of the comment 46 1.2 rillig .if ${VAR} != "not part of the comment" 47 1.2 rillig . error 48 1.2 rillig .endif 49 1.1 apb 50 1.2 rillig # To escape a comment sign, precede it with a backslash. 51 1.2 rillig VAR= \# # Both in the assignment. 52 1.2 rillig .if ${VAR} != "\#" # And in the comparison. 53 1.2 rillig . error 54 1.2 rillig .endif 55 1.2 rillig 56 1.2 rillig # Since 2012-03-24 the variable modifier :[#] does not need to be escaped. 57 1.2 rillig # To keep the parsing code simple, any "[#" does not start a comment, even 58 1.2 rillig # outside of a variable expression. 59 1.2 rillig WORDS= ${VAR:[#]} [# 60 1.2 rillig .if ${WORDS} != "1 [#" 61 1.2 rillig . error 62 1.2 rillig .endif 63 1.1 apb 64 1.3 rillig # An odd number of backslashes makes a line continuation, \\\ 65 1.2 rillig no matter if it is 3 or 5 \\\\\ 66 1.2 rillig or 9 backslashes. \\\\\\\\\ 67 1.2 rillig This is the last line of the comment. 68 1.2 rillig VAR= no comment anymore 69 1.2 rillig .if ${VAR} != "no comment anymore" 70 1.2 rillig . error 71 1.2 rillig .endif 72 1.1 apb 73 1.2 rillig all: 74 1.2 rillig # In the commands associated with a target, the '#' does not start a makefile 75 1.2 rillig # comment. The '#' is just passed to the shell, like any ordinary character. 76 1.2 rillig echo This is a shell comment: # comment 77 1.2 rillig # If the '#' were to start a makefile comment, the following shell command 78 1.2 rillig # would have unbalanced quotes. 79 1.2 rillig echo This is not a shell comment: '# comment' 80 1.2 rillig @echo A shell comment can#not start in the middle of a word. 81
Indexes created Sat Nov 01 21:09:44 GMT 2025