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This 16-bit number was 73 unused: 74 75 0x8888 (octal "\210\210") 76 77 but to be more certain, this 32-bit number was chosen: 78 79 0x88888888 (octal "\210\210\210\210") 80 81 This is the pattern submitted to the maintainers of the <STRONG>file</STRONG> 82 program: 83 84 # 85 # ncurses5 (and before) did not use a magic number, 86 # making screen dumps "data". 87 # 88 # ncurses6 (2015) uses this format, ignoring byte-order 89 0 string \210\210\210\210ncurses ncurses6 screen image 90 # 91 92 <STRONG>o</STRONG> The screen dumps are written in textual form, so that internal data 93 sizes are not directly related to the dump-format, and enabling the 94 library to read dumps from either narrow- or wide-character- 95 configurations. 96 97 The <EM>narrow</EM> library configuration holds characters and video 98 attributes in a 32-bit <STRONG>chtype</STRONG>, while the <EM>wide-character</EM> library 99 stores this information in the <STRONG>cchar_t</STRONG> structure, which is much 100 larger than 32-bits. 101 102 <STRONG>o</STRONG> It is possible to read a screen dump into a terminal with a 103 different screen-size, because the library truncates or fills the 104 screen as necessary. 105 106 <STRONG>o</STRONG> The ncurses6 <STRONG>getwin</STRONG> reads the legacy screen dumps from ncurses5. 107 108 109</PRE><H3><a name="h3-ncurses5-_Legacy_">ncurses5 (Legacy)</a></H3><PRE> 110 The screen-dump feature was added to <EM>ncurses</EM> in June 1995. While there 111 were fixes and improvements in succeeding years, the basic scheme was 112 unchanged: 113 114 <STRONG>o</STRONG> The <EM>WINDOW</EM> structure was written in binary form. 115 116 <STRONG>o</STRONG> The <EM>WINDOW</EM> structure refers to lines of data, which were written as 117 an array of binary data following the <EM>WINDOW</EM>. 118 119 <STRONG>o</STRONG> When <STRONG>getwin</STRONG> restored the window, it would keep track of offsets 120 into the array of line-data and adjust the <EM>WINDOW</EM> structure which 121 was read back into memory. 122 123 This is similar to Unix System V, but does not write a "magic number" 124 to identify the file format. 125 126 127</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> 128 There is no standard format for <EM>curses</EM> screen dumps. A brief survey of 129 the existing implementations follows. 130 131 132</PRE><H3><a name="h3-X_Open-Curses">X/Open Curses</a></H3><PRE> 133 X/Open Curses, Issue 7 specifies little. It says (boldface emphasis 134 added) 135 136 "[t]he <EM>getwin()</EM> function reads window-related data stored in the 137 file by <EM>putwin()</EM>. The function then creates and initializes a new 138 window using that data. 139 140 The <EM>putwin()</EM> function writes all data associated with <EM>win</EM> into the 141 <EM>stdio</EM> stream to which <EM>filep</EM> points, using an <STRONG>unspecified</STRONG> <STRONG>format</STRONG>. 142 This information can be retrieved later using <EM>getwin()</EM>." 143 144 In the mid-1990s when the X/Open Curses document was written, there 145 were still System V systems using older, less capable <EM>curses</EM> libraries. 146 BSD <EM>curses</EM> was not relevant to X/Open because it did not meet the 147 criteria for base-level conformance; see <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>. 148 149 150</PRE><H3><a name="h3-System-V">System V</a></H3><PRE> 151 System V <EM>curses</EM> identified the file format by writing a "magic number" 152 at the beginning of the dump. The <EM>WINDOW</EM> data and the lines of text 153 follow, all in binary form. 154 155 Solaris <EM>curses</EM> has the following definitions. 156 157 /* terminfo magic number */ 158 #define MAGNUM 0432 159 160 /* curses screen dump magic number */ 161 #define SVR2_DUMP_MAGIC_NUMBER 0433 162 #define SVR3_DUMP_MAGIC_NUMBER 0434 163 164 That is, the feature was likely introduced in SVr2 (1984), and improved 165 in SVr3 (1987). Solaris <EM>curses</EM> has no magic number for SVr4 (1989). 166 Other System V operating systems (AIX and HP-UX) use a magic number 167 that would correspond to the following. 168 169 /* curses screen dump magic number */ 170 #define SVR4_DUMP_MAGIC_NUMBER 0435 171 172 That octal number in bytes is 001, 035. Because most Unix vendors at 173 the time used big-endian hardware, the magic number is written with the 174 high-order byte first. 175 176 \001\035 177 178 After the magic number, the <EM>WINDOW</EM> structure and line data are written 179 in binary format. While the magic number used by these systems can be 180 observed with <STRONG>od(1)</STRONG>, none of them documents the format used for screen 181 dumps. 182 183 Nor do they use an identical format, even with the System V family. 184 The <EM>ncurses</EM> <EM>savescreen</EM> test program was used to collect information for 185 this manual page. It produced dumps of different size (all on 64-bit 186 hardware, on 40x80 screens): 187 188 <STRONG>o</STRONG> AIX (51817 bytes) 189 190 <STRONG>o</STRONG> HP-UX (90093 bytes) 191 192 <STRONG>o</STRONG> Solaris 10 (13273 bytes) 193 194 <STRONG>o</STRONG> <EM>ncurses</EM>5 (12888 bytes) 195 196 197</PRE><H3><a name="h3-Solaris">Solaris</a></H3><PRE> 198 As noted above, Solaris <EM>curses</EM> has no magic number corresponding to 199 SVr4 <EM>curses</EM>. This is odd, since Solaris was the first operating system 200 to meet the SVr4 guidelines. Solaris furthermore supplies two versions 201 of <EM>curses</EM>. 202 203 <STRONG>o</STRONG> The default <EM>curses</EM> library uses the SVr3 magic number. 204 205 <STRONG>o</STRONG> An alternate <EM>curses</EM> library (which we term <EM>xcurses),</EM> available in 206 <EM>/usr/xpg4</EM>, uses a textual format with no magic number. 207 208 According to its copyright notice, this <EM>xcurses</EM> library was 209 developed by MKS (Mortice Kern Systems) from 1990 to 1995. 210 211 Like ncurses6, it includes a header with parameters. Unlike 212 ncurses6, the contents of the window are written piecemeal, with 213 coordinates and attributes for each chunk of text rather than 214 writing the whole window from top to bottom. 215 216 217</PRE><H3><a name="h3-PDCurses">PDCurses</a></H3><PRE> 218 <EM>PDCurses</EM> added support for screen dumps in version 2.7 (2005). Like 219 System V and ncurses5, it writes the <EM>WINDOW</EM> structure in binary, but 220 begins the file with its three-byte identifier "PDC", followed by a 221 single-byte version number. 222 223 "PDC\001" 224 225 226</PRE><H3><a name="h3-NetBSD">NetBSD</a></H3><PRE> 227 As of April 2017, NetBSD <EM>curses</EM> does not support <STRONG>scr_dump</STRONG> and 228 <STRONG>scr_restore</STRONG> (or <STRONG>scr_init</STRONG>, <STRONG>scr_set</STRONG>), although it has <STRONG>putwin</STRONG> and <STRONG>getwin</STRONG>. 229 230 Like ncurses5, NetBSD <STRONG>putwin</STRONG> does not identify its dumps with a useful 231 magic number. It writes 232 233 <STRONG>o</STRONG> the <EM>curses</EM> shared library major and minor versions as the first two 234 bytes (for example, 7 and 1), 235 236 <STRONG>o</STRONG> followed by a binary dump of the <EM>WINDOW</EM>, 237 238 <STRONG>o</STRONG> some data for wide characters referenced by the <EM>WINDOW</EM> structure, 239 and 240 241 <STRONG>o</STRONG> finally, lines as done by other implementations. 242 243 244</PRE><H2><a name="h2-EXAMPLES">EXAMPLES</a></H2><PRE> 245 Given a simple program which writes text to the screen (and for the 246 sake of example, limiting the screen-size to 10x20): 247 248 #include <curses.h> 249 250 int 251 main(void) 252 { 253 putenv("LINES=10"); 254 putenv("COLUMNS=20"); 255 initscr(); 256 start_color(); 257 init_pair(1, COLOR_WHITE, COLOR_BLUE); 258 init_pair(2, COLOR_RED, COLOR_BLACK); 259 bkgd(<STRONG>COLOR_PAIR(1)</STRONG>); 260 move(4, 5); 261 attron(A_BOLD); 262 addstr("Hello"); 263 move(5, 5); 264 attroff(A_BOLD); 265 attrset(A_REVERSE | <STRONG>COLOR_PAIR(2)</STRONG>); 266 addstr("World!"); 267 refresh(); 268 scr_dump("foo.out"); 269 endwin(); 270 return 0; 271 } 272 273 When run using ncurses6, the output looks like this: 274 275 \210\210\210\210ncurses 6.0.20170415 276 _cury=5 277 _curx=11 278 _maxy=9 279 _maxx=19 280 _flags=14 281 _attrs=\{REVERSE|C2} 282 flag=_idcok 283 _delay=-1 284 _regbottom=9 285 _bkgrnd=\{NORMAL|C1}\s 286 rows: 287 1:\{NORMAL|C1}\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 288 2:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 289 3:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 290 4:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 291 5:\s\s\s\s\s\{BOLD}Hello\{NORMAL}\s\s\s\s\s\s\s\s\s\s 292 6:\s\s\s\s\s\{REVERSE|C2}World!\{NORMAL|C1}\s\s\s\s\s\s\s\s\s 293 7:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 294 8:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 295 9:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 296 10:\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s\s 297 298 The first four octal escapes are actually nonprinting characters, while 299 the remainder of the file is printable text. You may notice: 300 301 <STRONG>o</STRONG> The actual color pair values are not written to the file. 302 303 <STRONG>o</STRONG> All characters are shown in printable form; spaces are "\s" to 304 ensure they are not overlooked. 305 306 <STRONG>o</STRONG> Attributes are written in escaped curly braces, e.g., "\{BOLD}", 307 and may include a color pair (C1 or C2 in this example). 308 309 <STRONG>o</STRONG> The parameters in the header are written out only if they are 310 nonzero. When reading back, order does not matter. 311 312 Running the same program with Solaris <EM>xpg4</EM> curses gives this dump: 313 314 MAX=10,20 315 BEG=0,0 316 SCROLL=0,10 317 VMIN=1 318 VTIME=0 319 FLAGS=0x1000 320 FG=0,0 321 BG=0,0, 322 0,0,0,1, 323 0,19,0,0, 324 1,0,0,1, 325 1,19,0,0, 326 2,0,0,1, 327 2,19,0,0, 328 3,0,0,1, 329 3,19,0,0, 330 4,0,0,1, 331 4,5,0x20,0,Hello 332 4,10,0,1, 333 4,19,0,0, 334 5,0,0,1, 335 5,5,0x4,2,World! 336 5,11,0,1, 337 5,19,0,0, 338 6,0,0,1, 339 6,19,0,0, 340 7,0,0,1, 341 7,19,0,0, 342 8,0,0,1, 343 8,19,0,0, 344 9,0,0,1, 345 9,19,0,0, 346 CUR=11,5 347 348 Solaris <STRONG>getwin</STRONG> requires that all parameters are present, and in the 349 same order. The <EM>xpg4</EM> curses library does not know about the <STRONG>bce</STRONG> (back 350 color erase) capability, and does not color the window background. 351 352 On the other hand, the SVr4 curses library does know about the 353 background color. However, its screen dumps are in binary. Here is 354 the corresponding dump (using "od -t x1"): 355 356 0000000 1c 01 c3 d6 f3 58 05 00 0b 00 0a 00 14 00 00 00 357 0000020 00 00 02 00 00 00 00 00 00 00 00 00 00 00 00 00 358 0000040 00 00 b8 1a 06 08 cc 1a 06 08 00 00 09 00 10 00 359 0000060 00 00 00 80 00 00 20 00 00 00 ff ff ff ff 00 00 360 0000100 ff ff ff ff 00 00 00 00 20 80 00 00 20 80 00 00 361 0000120 20 80 00 00 20 80 00 00 20 80 00 00 20 80 00 00 362 * 363 0000620 20 80 00 00 20 80 00 00 20 80 00 00 48 80 00 04 364 0000640 65 80 00 04 6c 80 00 04 6c 80 00 04 6f 80 00 04 365 0000660 20 80 00 00 20 80 00 00 20 80 00 00 20 80 00 00 366 * 367 0000740 20 80 00 00 20 80 00 00 20 80 00 00 57 00 81 00 368 0000760 6f 00 81 00 72 00 81 00 6c 00 81 00 64 00 81 00 369 0001000 21 00 81 00 20 80 00 00 20 80 00 00 20 80 00 00 370 0001020 20 80 00 00 20 80 00 00 20 80 00 00 20 80 00 00 371 * 372 0001540 20 80 00 00 20 80 00 00 00 00 f6 d1 01 00 f6 d1 373 0001560 08 00 00 00 40 00 00 00 00 00 00 00 00 00 00 07 374 0001600 00 04 00 01 00 01 00 00 00 01 00 00 00 00 00 00 375 0001620 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 376 * 377 0002371 378 379 380</PRE><H2><a name="h2-AUTHORS">AUTHORS</a></H2><PRE> 381 Thomas E. Dickey 382 extended screen-dump format for <EM>ncurses</EM> 6.0 (2015) 383 384 Eric S. Raymond 385 screen dump feature in <EM>ncurses</EM> 1.9.2d (1995) 386 387 388</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> 389 <STRONG><A HREF="curs_scr_dump.3x.html">curs_scr_dump(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG> 390 391 392 393ncurses 6.5 2024-03-23 <STRONG><A HREF="scr_dump.5.html">scr_dump(5)</A></STRONG> 394</PRE> 395<div class="nav"> 396<ul> 397<li><a href="#h2-NAME">NAME</a></li> 398<li><a href="#h2-DESCRIPTION">DESCRIPTION</a> 399<ul> 400<li><a href="#h3-ncurses6">ncurses6</a></li> 401<li><a href="#h3-ncurses5-_Legacy_">ncurses5 (Legacy)</a></li> 402</ul> 403</li> 404<li><a href="#h2-PORTABILITY">PORTABILITY</a> 405<ul> 406<li><a href="#h3-X_Open-Curses">X/Open Curses</a></li> 407<li><a href="#h3-System-V">System V</a></li> 408<li><a href="#h3-Solaris">Solaris</a></li> 409<li><a href="#h3-PDCurses">PDCurses</a></li> 410<li><a href="#h3-NetBSD">NetBSD</a></li> 411</ul> 412</li> 413<li><a href="#h2-EXAMPLES">EXAMPLES</a></li> 414<li><a href="#h2-AUTHORS">AUTHORS</a></li> 415<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> 416</ul> 417</div> 418</BODY> 419</HTML> 420