对开源或第三方代码进行修改,我们需要将原始代码和修改部分分别上传.此时,需要先将修改的部分使用diff提取出来,记录为patch文件.其他人使用时,下载原始代码和patch文件,通过patch命令恢复为和你修改后同样的代码.
比如,将kernel原始代码的目录记为a,修改后的kernel代码目录记为b.提取差异为kernel.patch文件,可使用命令,
diff -arNu a b > kernel.patch
注意,使用-a选项是为了将二进制文件也作为文本文件处理进行对比.
在原始代码中,需要打上此补丁时,可以使用命令(先进入原始代码目录a中),
cd a; patch -p1 < ../kernel.patch
附上diff命令的说明.
1 用法：diff [选项]... FILES 2 Compare FILES line by line. 3 4 Mandatory arguments to long options are mandatory for short options too. 5 --normal output a normal diff (the default) 6 -q, --brief report only when files differ 7 -s, --report-identical-files report when two files are the same 8 -c, -C NUM, --context[=NUM] output NUM (default 3) lines of copied context 9 -u, -U NUM, --unified[=NUM] output NUM (default 3) lines of unified context 10 -e, --ed output an ed script 11 -n, --rcs output an RCS format diff 12 -y, --side-by-side output in two columns 13 -W, --width=NUM output at most NUM (default 130) print columns 14 --left-column output only the left column of common lines 15 --suppress-common-lines do not output common lines 16 17 -p, --show-c-function show which C function each change is in 18 -F, --show-function-line=RE show the most recent line matching RE 19 --label LABEL use LABEL instead of file name 20 (can be repeated) 21 22 -t, --expand-tabs expand tabs to spaces in output 23 -T, --initial-tab make tabs line up by prepending a tab 24 --tabsize=NUM tab stops every NUM (default 8) print columns 25 --suppress-blank-empty suppress space or tab before empty output lines 26 -l, --paginate pass output through 'pr' to paginate it 27 28 -r, --recursive recursively compare any subdirectories found 29 --no-dereference don't follow symbolic links 30 -N, --new-file treat absent files as empty 31 --unidirectional-new-file treat absent first files as empty 32 --ignore-file-name-case ignore case when comparing file names 33 --no-ignore-file-name-case consider case when comparing file names 34 -x, --exclude=PAT exclude files that match PAT 35 -X, --exclude-from=FILE exclude files that match any pattern in FILE 36 -S, --starting-file=FILE start with FILE when comparing directories 37 --from-file=FILE1 compare FILE1 to all operands; 38 FILE1 can be a directory 39 --to-file=FILE2 compare all operands to FILE2; 40 FILE2 can be a directory 41 42 -i, --ignore-case ignore case differences in file contents 43 -E, --ignore-tab-expansion ignore changes due to tab expansion 44 -Z, --ignore-trailing-space ignore white space at line end 45 -b, --ignore-space-change ignore changes in the amount of white space 46 -w, --ignore-all-space ignore all white space 47 -B, --ignore-blank-lines ignore changes where lines are all blank 48 -I, --ignore-matching-lines=RE ignore changes where all lines match RE 49 50 -a, --text treat all files as text 51 --strip-trailing-cr strip trailing carriage return on input 52 53 -D, --ifdef=NAME output merged file with '#ifdef NAME' diffs 54 --GTYPE-group-format=GFMT format GTYPE input groups with GFMT 55 --line-format=LFMT format all input lines with LFMT 56 --LTYPE-line-format=LFMT format LTYPE input lines with LFMT 57 These format options provide fine-grained control over the output 58 of diff, generalizing -D/--ifdef. 59 LTYPE is 'old', 'new', or 'unchanged'. GTYPE is LTYPE or 'changed'. 60 GFMT (only) may contain: 61 %< lines from FILE1 62 %> lines from FILE2 63 %= lines common to FILE1 and FILE2 64 %[-][WIDTH][.[PREC]]{doxX}LETTER printf-style spec for LETTER 65 LETTERs are as follows for new group, lower case for old group: 66 F first line number 67 L last line number 68 N number of lines = L-F+1 69 E F-1 70 M L+1 71 %(A=B?T:E) if A equals B then T else E 72 LFMT (only) may contain: 73 %L contents of line 74 %l contents of line, excluding any trailing newline 75 %[-][WIDTH][.[PREC]]{doxX}n printf-style spec for input line number 76 Both GFMT and LFMT may contain: 77 %% % 78 %c'C' the single character C 79 %c'\OOO' the character with octal code OOO 80 C the character C (other characters represent themselves) 81 82 -d, --minimal try hard to find a smaller set of changes 83 --horizon-lines=NUM keep NUM lines of the common prefix and suffix 84 --speed-large-files assume large files and many scattered small changes 85 86 --help display this help and exit 87 -v, --version output version information and exit 88 89 FILES are 'FILE1 FILE2' or 'DIR1 DIR2' or 'DIR FILE...' or 'FILE... DIR'. 90 If --from-file or --to-file is given, there are no restrictions on FILE(s). 91 If a FILE is '-', read standard input. 92 如果输入相同，则退出状态为 0；1 表示输入不同；2 表示有错误产生。 93 94 Report bugs to: bug-diffutils@gnu.org 95 GNU diffutils home page: <http://www.gnu.org/software/diffutils/> 96 General help using GNU software: <http://www.gnu.org/gethelp/>