1The output format from "git-diff-index", "git-diff-tree" and 2"git-diff-files" are very similar. 3 4These commands all compare two sets of things; what is 5compared differs: 6 7git-diff-index <tree-ish>:: 8 compares the <tree-ish> and the files on the filesystem. 9 10git-diff-index --cached <tree-ish>:: 11 compares the <tree-ish> and the index. 12 13git-diff-tree [-r] <tree-ish-1> <tree-ish-2> [<pattern>...]:: 14 compares the trees named by the two arguments. 15 16git-diff-files [<pattern>...]:: 17 compares the index and the files on the filesystem. 18 19 20An output line is formatted this way: 21 22------------------------------------------------ 23in-place edit :100644 100644 bcd1234... 0123456... M file0 24copy-edit :100644 100644 abcd123... 1234567... C68 file1 file2 25rename-edit :100644 100644 abcd123... 1234567... R86 file1 file3 26create :000000 100644 0000000... 1234567... A file4 27delete :100644 000000 1234567... 0000000... D file5 28unmerged :000000 000000 0000000... 0000000... U file6 29------------------------------------------------ 30 31That is, from the left to the right: 32 33. a colon. 34. mode for "src"; 000000 if creation or unmerged. 35. a space. 36. mode for "dst"; 000000 if deletion or unmerged. 37. a space. 38. sha1 for "src"; 0\{40\} if creation or unmerged. 39. a space. 40. sha1 for "dst"; 0\{40\} if creation, unmerged or "look at work tree". 41. a space. 42. status, followed by optional "score" number. 43. a tab or a NUL when '-z' option is used. 44. path for "src" 45. a tab or a NUL when '-z' option is used; only exists for C or R. 46. path for "dst"; only exists for C or R. 47. an LF or a NUL when '-z' option is used, to terminate the record. 48 49<sha1> is shown as all 0's if a file is new on the filesystem 50and it is out of sync with the index. 51 52Example: 53 54------------------------------------------------ 55:100644 100644 5be4a4...... 000000...... M file.c 56------------------------------------------------ 57 58When `-z` option is not used, TAB, LF, and backslash characters 59in pathnames are represented as `\t`, `\n`, and `\\`, 60respectively. 61 62 63Generating patches with -p 64-------------------------- 65 66When "git-diff-index", "git-diff-tree", or "git-diff-files" are run 67with a '-p' option, they do not produce the output described above; 68instead they produce a patch file. 69 70The patch generation can be customized at two levels. 71 721. When the environment variable 'GIT_EXTERNAL_DIFF' is not set, 73 these commands internally invoke "diff" like this: 74 75 diff -L a/<path> -L b/<path> -pu <old> <new> 76+ 77For added files, `/dev/null` is used for <old>. For removed 78files, `/dev/null` is used for <new> 79+ 80The "diff" formatting options can be customized via the 81environment variable 'GIT_DIFF_OPTS'. For example, if you 82prefer context diff: 83 84 GIT_DIFF_OPTS=-c git-diff-index -p HEAD 85 86 872. When the environment variable 'GIT_EXTERNAL_DIFF' is set, the 88 program named by it is called, instead of the diff invocation 89 described above. 90+ 91For a path that is added, removed, or modified, 92'GIT_EXTERNAL_DIFF' is called with 7 parameters: 93 94 path old-file old-hex old-mode new-file new-hex new-mode 95+ 96where: 97 98 <old|new>-file:: are files GIT_EXTERNAL_DIFF can use to read the 99 contents of <old|new>, 100 <old|new>-hex:: are the 40-hexdigit SHA1 hashes, 101 <old|new>-mode:: are the octal representation of the file modes. 102 103+ 104The file parameters can point at the user's working file 105(e.g. `new-file` in "git-diff-files"), `/dev/null` (e.g. `old-file` 106when a new file is added), or a temporary file (e.g. `old-file` in the 107index). 'GIT_EXTERNAL_DIFF' should not worry about unlinking the 108temporary file --- it is removed when 'GIT_EXTERNAL_DIFF' exits. 109 110For a path that is unmerged, 'GIT_EXTERNAL_DIFF' is called with 1 111parameter, <path>. 112 113 114git specific extension to diff format 115------------------------------------- 116 117What -p option produces is slightly different from the 118traditional diff format. 119 1201. It is preceded with a "git diff" header, that looks like 121 this: 122 123 diff --git a/file1 b/file2 124+ 125The `a/` and `b/` filenames are the same unless rename/copy is 126involved. Especially, even for a creation or a deletion, 127`/dev/null` is _not_ used in place of `a/` or `b/` filenames. 128+ 129When rename/copy is involved, `file1` and `file2` show the 130name of the source file of the rename/copy and the name of 131the file that rename/copy produces, respectively. 132 1332. It is followed by one or more extended header lines: 134 135 old mode <mode> 136 new mode <mode> 137 deleted file mode <mode> 138 new file mode <mode> 139 copy from <path> 140 copy to <path> 141 rename from <path> 142 rename to <path> 143 similarity index <number> 144 dissimilarity index <number> 145 index <hash>..<hash> <mode> 146 1473. TAB, LF, and backslash characters in pathnames are 148 represented as `\t`, `\n`, and `\\`, respectively. 149 150 151combined diff format 152-------------------- 153 154git-diff-tree and git-diff-files can take '-c' or '--cc' option 155to produce 'combined diff', which looks like this: 156 157------------ 158diff --combined describe.c 159index fabadb8,cc95eb0..4866510 160--- a/describe.c 161+++ b/describe.c 162@@@ -98,20 -98,12 +98,20 @@@ 163 return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1; 164 } 165 166- static void describe(char *arg) 167 -static void describe(struct commit *cmit, int last_one) 168++static void describe(char *arg, int last_one) 169 { 170 + unsigned char sha1[20]; 171 + struct commit *cmit; 172 struct commit_list *list; 173 static int initialized = 0; 174 struct commit_name *n; 175 176 + if (get_sha1(arg, sha1) < 0) 177 + usage(describe_usage); 178 + cmit = lookup_commit_reference(sha1); 179 + if (!cmit) 180 + usage(describe_usage); 181 + 182 if (!initialized) { 183 initialized = 1; 184 for_each_ref(get_name); 185------------ 186 1871. It is preceded with a "git diff" header, that looks like 188 this (when '-c' option is used): 189 190 diff --combined file 191+ 192or like this (when '--cc' option is used): 193 194 diff --c file 195 1962. It is followed by one or more extended header lines 197 (this example shows a merge with two parents): 198 199 index <hash>,<hash>..<hash> 200 mode <mode>,<mode>..<mode> 201 new file mode <mode> 202 deleted file mode <mode>,<mode> 203+ 204The `mode <mode>,<mode>..<mode>` line appears only if at least one of 205the <mode> is diferent from the rest. Extended headers with 206information about detected contents movement (renames and 207copying detection) are designed to work with diff of two 208<tree-ish> and are not used by combined diff format. 209 2103. It is followed by two-line from-file/to-file header 211 212 --- a/file 213 +++ b/file 214+ 215Contrary to two-line header for traditional 'unified' diff 216format, and similar to filenames in ordinary "diff header", 217/dev/null is not used for creation or deletion. 218 2194. Chunk header format is modified to prevent people from 220 accidentally feeding it to `patch -p1`. Combined diff format 221 was created for review of merge commit changes, and was not 222 meant for apply. The change is similar to the change in the 223 extended 'index' header: 224 225 @@@ <from-file-range> <from-file-range> <to-file-range> @@@ 226+ 227There are (number of parents + 1) `@` characters in the chunk 228header for combined diff format. 229 230Unlike the traditional 'unified' diff format, which shows two 231files A and B with a single column that has `-` (minus -- 232appears in A but removed in B), `+` (plus -- missing in A but 233added to B), or `" "` (space -- unchanged) prefix, this format 234compares two or more files file1, file2,... with one file X, and 235shows how X differs from each of fileN. One column for each of 236fileN is prepended to the output line to note how X's line is 237different from it. 238 239A `-` character in the column N means that the line appears in 240fileN but it does not appear in the result. A `+` character 241in the column N means that the line appears in the last file, 242and fileN does not have that line (in other words, the line was 243added, from the point of view of that parent). 244 245In the above example output, the function signature was changed 246from both files (hence two `-` removals from both file1 and 247file2, plus `++` to mean one line that was added does not appear 248in either file1 nor file2). Also two other lines are the same 249from file1 but do not appear in file2 (hence prefixed with ` +`). 250 251When shown by `git diff-tree -c`, it compares the parents of a 252merge commit with the merge result (i.e. file1..fileN are the 253parents). When shown by `git diff-files -c`, it compares the 254two unresolved merge parents with the working tree file 255(i.e. file1 is stage 2 aka "our version", file2 is stage 3 aka 256"their version"). 257