【背景】
折腾：
【记录】尝试为了Buildroot编译期间涉及到的m4-1.4.16的fpending在Cygwin下的问题去制作diff和patch补丁包
期间，需要搞懂diff的参数purN的含义。
【折腾过程】
1.去看看help：
CLi@PC-CLI-1 ~/develop/buildroot/diff_patch
$ diff --help
Usage: diff [OPTION]... FILES
Compare FILES line by line.
Mandatory arguments to long options are mandatory for short options too.
--normal output a normal diff (the default)
-q, --brief report only when files differ
-s, --report-identical-files report when two files are the same
-c, -C NUM, --context[=NUM] output NUM (default 3) lines of copied context
-u, -U NUM, --unified[=NUM] output NUM (default 3) lines of unified context
-e, --ed output an ed script
-n, --rcs output an RCS format diff
-y, --side-by-side output in two columns
-W, --width=NUM output at most NUM (default 130) print columns
--left-column output only the left column of common lines
--suppress-common-lines do not output common lines
-p, --show-c-function show which C function each change is in
-F, --show-function-line=RE show the most recent line matching RE
--label LABEL use LABEL instead of file name
(can be repeated)
-t, --expand-tabs expand tabs to spaces in output
-T, --initial-tab make tabs line up by prepending a tab
--tabsize=NUM tab stops every NUM (default 8) print columns
--suppress-blank-empty suppress space or tab before empty output lines
-l, --paginate pass output through `pr' to paginate it
-r, --recursive recursively compare any subdirectories found
-N, --new-file treat absent files as empty
--unidirectional-new-file treat absent first files as empty
--ignore-file-name-case ignore case when comparing file names
--no-ignore-file-name-case consider case when comparing file names
-x, --exclude=PAT exclude files that match PAT
-X, --exclude-from=FILE exclude files that match any pattern in FILE
-S, --starting-file=FILE start with FILE when comparing directories
--from-file=FILE1 compare FILE1 to all operands;
FILE1 can be a directory
--to-file=FILE2 compare all operands to FILE2;
FILE2 can be a directory
-i, --ignore-case ignore case differences in file contents
-E, --ignore-tab-expansion ignore changes due to tab expansion
-Z, --ignore-trailing-space ignore white space at line end
-b, --ignore-space-change ignore changes in the amount of white space
-w, --ignore-all-space ignore all white space
-B, --ignore-blank-lines ignore changes whose lines are all blank
-I, --ignore-matching-lines=RE ignore changes whose lines all match RE
-a, --text treat all files as text
--strip-trailing-cr strip trailing carriage return on input
--binary read and write data in binary mode
-D, --ifdef=NAME output merged file with `#ifdef NAME' diffs
--GTYPE-group-format=GFMT format GTYPE input groups with GFMT
--line-format=LFMT format all input lines with LFMT
--LTYPE-line-format=LFMT format LTYPE input lines with LFMT
These format options provide fine-grained control over the output
of diff, generalizing -D/--ifdef.
LTYPE is `old', `new', or `unchanged'. GTYPE is LTYPE or `changed'.
GFMT (only) may contain:
%< lines from FILE1
%> lines from FILE2
%= lines common to FILE1 and FILE2
%[-][WIDTH][.[PREC]]{doxX}LETTER printf-style spec for LETTER
LETTERs are as follows for new group, lower case for old group:
F first line number
L last line number
N number of lines = L-F+1
E F-1
M L+1
%(A=B?T:E) if A equals B then T else E
LFMT (only) may contain:
%L contents of line
%l contents of line, excluding any trailing newline
%[-][WIDTH][.[PREC]]{doxX}n printf-style spec for input line number
Both GFMT and LFMT may contain:
%% %
%c'C' the single character C
%c'\OOO' the character with octal code OOO
C the character C (other characters represent themselves)
-d, --minimal try hard to find a smaller set of changes
--horizon-lines=NUM keep NUM lines of the common prefix and suffix
--speed-large-files assume large files and many scattered small changes
--help display this help and exit
-v, --version output version information and exit
FILES are `FILE1 FILE2' or `DIR1 DIR2' or `DIR FILE...' or `FILE... DIR'.
If --from-file or --to-file is given, there are no restrictions on FILE(s).
If a FILE is `-', read standard input.
Exit status is 0 if inputs are the same, 1 if different, 2 if trouble.
Report bugs to: [email protected]
GNU diffutils home page: <http://www.gnu.org/software/diffutils/>
General help using GNU software: <http://www.gnu.org/gethelp/>
CLi@PC-CLI-1 ~/develop/buildroot/diff_patch
$【总结】
对于purN的参数的含义是：
- p：显示变化所在的C函数
- u：显示标准（默认3行）的上下文
- r：递归
- N：把不存在的文件视为新文件
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