1Jeremy Bornstein wrote: 2 3I recently had the need to transfer files only with different mod 4dates (and to *not* transfer them based on file size differences). 5This is because I'm backing up files remotely on an untrusted machine, 6so I'm encrypting them with gpg before transfer. I discovered that 7rsync didn't already have a --date-only flag, so I added one and am 8enclosing the diffs in case you (as I hope) decide to include this 9option in future releases. 10 11To use this patch, run these commands for a successful build: 12 13 patch -p1 <patches/date-only.diff 14 ./configure (optional if already run) 15 make 16 17--- old/generator.c 18+++ new/generator.c 19@@ -60,6 +60,7 @@ extern int append_mode; 20 extern int make_backups; 21 extern int csum_length; 22 extern int ignore_times; 23+extern int date_only; 24 extern int size_only; 25 extern OFF_T max_size; 26 extern OFF_T min_size; 27@@ -378,6 +379,8 @@ void itemize(struct file_struct *file, i 28 /* Perform our quick-check heuristic for determining if a file is unchanged. */ 29 int unchanged_file(char *fn, struct file_struct *file, STRUCT_STAT *st) 30 { 31+ if (date_only) 32+ return cmp_time(st->st_mtime, file->modtime) == 0; 33 if (st->st_size != file->length) 34 return 0; 35 36--- old/options.c 37+++ new/options.c 38@@ -99,6 +99,7 @@ int keep_partial = 0; 39 int safe_symlinks = 0; 40 int copy_unsafe_links = 0; 41 int size_only = 0; 42+int date_only = 0; 43 int daemon_bwlimit = 0; 44 int bwlimit = 0; 45 int fuzzy_basis = 0; 46@@ -343,6 +344,7 @@ void usage(enum logcode F) 47 rprintf(F," --timeout=TIME set I/O timeout in seconds\n"); 48 rprintf(F," -I, --ignore-times don't skip files that match in size and mod-time\n"); 49 rprintf(F," --size-only skip files that match in size\n"); 50+ rprintf(F," --date-only skip files that match in mod-time\n"); 51 rprintf(F," --modify-window=NUM compare mod-times with reduced accuracy\n"); 52 rprintf(F," -T, --temp-dir=DIR create temporary files in directory DIR\n"); 53 rprintf(F," -y, --fuzzy find similar file for basis if no dest file\n"); 54@@ -463,6 +465,7 @@ static struct poptOption long_options[] 55 {"chmod", 0, POPT_ARG_STRING, 0, OPT_CHMOD, 0, 0 }, 56 {"ignore-times", 'I', POPT_ARG_NONE, &ignore_times, 0, 0, 0 }, 57 {"size-only", 0, POPT_ARG_NONE, &size_only, 0, 0, 0 }, 58+ {"date-only", 0, POPT_ARG_NONE, &date_only, 0, 0, 0 }, 59 {"one-file-system", 'x', POPT_ARG_NONE, 0, 'x', 0, 0 }, 60 {"update", 'u', POPT_ARG_NONE, &update_only, 0, 0, 0 }, 61 {"existing", 0, POPT_ARG_NONE, &ignore_non_existing, 0, 0, 0 }, 62@@ -1676,6 +1679,9 @@ void server_options(char **args,int *arg 63 args[ac++] = "--size-only"; 64 } 65 66+ if (date_only) 67+ args[ac++] = "--date-only"; 68+ 69 if (modify_window_set) { 70 if (asprintf(&arg, "--modify-window=%d", modify_window) < 0) 71 goto oom; 72--- old/rsync.yo 73+++ new/rsync.yo 74@@ -360,6 +360,7 @@ to the detailed description below for a 75 --timeout=TIME set I/O timeout in seconds 76 -I, --ignore-times don't skip files that match size and time 77 --size-only skip files that match in size 78+ --date-only skip files that match in mod-time 79 --modify-window=NUM compare mod-times with reduced accuracy 80 -T, --temp-dir=DIR create temporary files in directory DIR 81 -y, --fuzzy find similar file for basis if no dest file 82@@ -477,6 +478,12 @@ regardless of timestamp. This is useful 83 after using another mirroring system which may not preserve timestamps 84 exactly. 85 86+dit(bf(--date-only)) Normally rsync will skip any files that are 87+already the same size and have the same modification time-stamp. With the 88+--date-only option, files will be skipped if they have the same 89+timestamp, regardless of size. This may be useful when the remote 90+files have passed through a size-changing filter, e.g. for encryption. 91+ 92 dit(bf(--modify-window)) When comparing two timestamps, rsync treats the 93 timestamps as being equal if they differ by no more than the modify-window 94 value. This is normally 0 (for an exact match), but you may find it useful 95--- old/rsync.1 96+++ new/rsync.1 97@@ -426,6 +426,7 @@ to the detailed description below for a 98 \-\-timeout=TIME set I/O timeout in seconds 99 \-I, \-\-ignore\-times don\&'t skip files that match size and time 100 \-\-size\-only skip files that match in size 101+ \-\-date\-only skip files that match in mod-time 102 \-\-modify\-window=NUM compare mod-times with reduced accuracy 103 \-T, \-\-temp\-dir=DIR create temporary files in directory DIR 104 \-y, \-\-fuzzy find similar file for basis if no dest file 105@@ -556,6 +557,13 @@ regardless of timestamp\&. This is usefu 106 after using another mirroring system which may not preserve timestamps 107 exactly\&. 108 .IP 109+.IP "\fB\-\-date\-only\fP" 110+Normally rsync will skip any files that are 111+already the same size and have the same modification time-stamp\&. With the 112+\-\-date\-only option, files will be skipped if they have the same 113+timestamp, regardless of size\&. This may be useful when the remote 114+files have passed through a size-changing filter, e\&.g\&. for encryption\&. 115+.IP 116 .IP "\fB\-\-modify\-window\fP" 117 When comparing two timestamps, rsync treats the 118 timestamps as being equal if they differ by no more than the modify-window 119