Less bugs and enhancement requests (OLD)

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NOTE: This page is OBSOLETE and is retained for historical purposes only.
Current and new bugs are managed on github.

This is a list of the known bugs in less.

Ref number Reported in version Fixed in version Description
311 541 open Using the F command when an & filter is in effect may cause extranous "skipping" messages to be displayed.
310 530 531 The "v" command does not work correctly if the filename contains shell metacharacters.
309 530 531 Less passes invalid parameters to the editor if you use the "v" command on an empty file.
302 458 open Less cannot be quit if invoked with the option ++h.
301 458 open In some cases, using more than one + command line option produces unexpected results.
300 458 481 The F command does not work on piped input.
299 458 open If "pattern" does not appear in file, "less +/pattern file" displays "Pattern not found" before displaying any of the file contents.
295 444 448 With -J and -S in effect, scrolling backwards to a line matching the current pattern does not display an asterisk in the status column if the matched pattern is beyond the visible part of the line.
294 436 Probably will not fix With the -R flag, less only honors coloring within a single line. If a color extends across a newline, the color is reset at the start of the next line.
The performance cost of implementing multi-line coloring is excessive. For example, when jumping to the end of the file using the G command, less could no longer just seek to the end of the file, but would need to read and parse any color sequences in the entire file.
293 436 open On some systems, if the shell which invokes less is catching SIGCHLD (eg. "trap name SIGCHLD" in bash), and less is invoked in a pipeline, then when one of the processes in the pipeline exits, less is stopped.
292 436 open Searching doesn't work correctly when the search pattern matches text that is hidden by the & command.
291 436 437 The p command may move to a line close to, but not exactly at, the specified percentage into the file if the file is large.
290 436 437 Trying to set the --follow-name option from within less fails with the message "Cannot change the -. option".
289 429 431 If a search pattern matches the last character on a line, it may not be highlighted correctly.
288 429 434 Searching with regular expressions turned off (via ctrl-R) does not work.
287 429 434 If a character whose display form is longer than one character (such as a control character) appears near the end of a screen line, the screen display can be incorrect.
286 429 430 If viewing standard input and the LESSOPEN variable does not begin with vertical bar, the LESSOPEN script will be passed a filename "-". The script should be invoked only if the LESSOPEN variable begins with a dash.
284 418 429 There is code in ch.c which uses pointer aliasing in a manner which is not ANSI compliant. This causes problems when compiled with the IBM XL compiler unless compiled with -qalias=noansi.
283 418 453 It is difficult to pass a literal dollar sign ($) as the parameter of a command line option because $ has a special meaning in option parameters.
281 416 418 Searching with -R in effect does not find text containing embedded ANSI color escape sequences.
280 416 418 Using -r in UTF-8 mode with text that contains a 0x9B byte can cause a crash.
278 408 416 Searching in text containing certain invalid UTF-8 characters causes a crash.
277 406 415 Case-insensitive searches using -i or -I do not work correctly when searching non-ASCII text.
273 394 485 Double-wide characters are not displayed correctly when typed into a search command.
271 394 As designed If a short file contains lines longer than the screen width, and the -F and -S options are specified, less will prompt rather than exiting after displaying the entire file.
This is by design, because the -S option causes the long lines to be truncated. Thus, exiting immediately would cause some parts of the file to never be seen. The -F option only exits if the entire file can be displayed on one screen.
270 394 As designed Less reports "terminal is not fully functional" on some HP-UX Itanium systems, because these systems use non-standard return values from tgetent.
Workaround: on such systems, edit defines.h and define TGETENT_OK as 0 before running "make".
268 394 388 If a file is mentioned more than once in the command line, such as less aa bb aa cc less will display the files in an unexpected order.
263 381 open Using uppercase metacharacters such as "\W" in a search pattern may not work. The uppercase metacharacters are handled incorrectly if -i or -I is in effect.
262 381 388 If you press h while the display is shifted, the help file will also be shifted.
261 381 388 If you search in the help file and the search fails, the help file is incorrectly entered into the list of input files.
260 381 388 If you press = with a long filename so the message occupies more than one line (with "press RETURN"), and then immediately enter a search command which matches without screen movement, the display is incorrect.
258 376 open On some systems, the F command may hang if the input is an active pipe.
257 378 388 A file containing UTF-8 "composing" or "combining" characters may not break lines at the correct positions.
256 378 388 Entering multibyte UTF-8 characters on the command line (for example, in a search string) may not work correctly.
255 378 396 To be consistent with current POSIX specification of "more", -p argument should be a command, not a search pattern.
252 376 378 The Windows version can produce invalid display if the file contains carriage returns and long lines.
251 376 378 The default buffer size per file is unlimited, not 64K as documented.
250 358 419 Using +G with -F causes less to quit immediately, even if the file doesn't fit on one screen.
249 358 388 In file with color sequences hidden via -R, search highlighting can change colors after the highlight.
248 358 376 In file with color sequences hidden via -R, search can fail due to embedded color sequences.
247 358 open Searching for ^$ with -s in effect won't go past multiple blank lines.
244 - 438 Should allocate ungetcc space dynamically.
240 358 367 Declaration of utf_len uses non-K&R syntax.
237 - As designed Improper use of #stop in lesskey file makes digits stop working.
236 - 357 Support sigprocmask for Cygwin compiler.
235 - 356 Don't use extension .dsm.
231 - 354 Make configure script prefer xcurses over curses, and curses+termcap over termcap.
229 - 354 Won't compile with SECURE=1.
228 - 353 Cannot have space after option that takes numeric argument.
226 - open Fix signal handling race when less is in a pipeline.
222 - 351 Fix standout/clear bug on "ut" terminals.
218 - 343 h:d crashes.
217 - 343 Change iprintf name to avoid conflict with Cygwin compiler.
213 - 343 lesskey doesn't work with CR-LF lines.
212 - As designed less -N with redirected output doesn't produce line numbers.
211 - 382 or earlier Cannot open a file that starts / ends with double quotes.
209 - 343 Searching for a pattern ending in $ doesn't work with CR-LF lines.
208 - 342 Should not set '' mark in help file.
207 - 342 Should check entire page before saying "Nothing to search".
205 - 340 -G suppress -W hiliting.
204 - 340 F while a search pattern is active doesn't go to end of long line.
203 - 364 Windows MSC highlights too much on line wrap.
202 - 364 DJGPP highlights too much on line wrap.
201 - Will not fix DJGPP cannot use long filenames on Windows/NT.
This is an issue with the interface between DJGPP and Windows, and cannot be fixed by less.
199 - open less +F on file with no newline at end causes new chars to display on next line.
198 - 334 On Windows, "j" at EOF scrolls down.
196 - 331 CAPS LOCK leaks characters in Windows.
194 - 331 Resolve issue when buffer is bigger than display window.
192 - 335 (see note) Search highlighting may be incorrect when search pattern uses ^.
NOTE: Fixed only if less is built with the POSIX or PCRE regex library.
190 - As designed Csh says "stty: TCGETS: Operation not supported on socket" on filename completion.
See this FAQ entry.
186 - open Last line of pipe on end of screen; doesn't say END.
185 - 376 Arrow keys don't work with -X (on some terminals).
181 - 325 Linux can't link with ncurses & termcap.
179 - 376 Searching may fail in files with very long lines.
178 - 322 Linux does "stty 0".
176 - 322 ! command while viewing help file crashes.
174 - 400 (see note) Search does not find string which occurs in a line after a null (\0) byte.
NOTE: Fixed in 400 if built with the PCRE regex library, or if no-regex searching is done via ctrl-R.
173 - Will not fix Fix filename completion in OS-9.
171 - Will not fix Fix OS-9 Ultra C build.
170 - 334 Fix MS-DOS Microsoft C build.
168 - 340 Add lesskey feature to toggle option without prompting.
167 - open Setting -S when top line is tail of a wrapped line causes bad display.
166 - 317 Configure fails on AIX (bad substitution).
165 - open Make %L always work when line numbers are on.
163 - 315 "!a;TAB" gives shell error msg.
161 - 308 Fix -d.
157 - 307 date | less > foo produces an escape sequence at end of foo.
156 - 307 Bad display on "/^Kpattern" in squished mode.
152 - Will not fix Sun cmdtool pipe bug.
150 - ? Two -D options on cmd line: second ignored.
149 - 299 Pause after !cmd before sending "ti".
146 - 299 Fix percent overflow in jump_percent.
143 - 311 "!cmd, v" goes to EOF.
142 - 334 Running less over telnet, then quit telnet; less hangs.
141 - 305 LESS=-kfilename; can't set LESS in the #env section.
140 - 304 Add mechanism to set SECURE mode at runtime.
138 - Will not fix /a[1,2] on Solaris matches a1, a2 and a4.
137 - 295 Search in squished file gives "Nothing to search" but then repaints badly.
136 - 295 Linux gets seg fault when TERM=abc (Don't call termcap funcs if tgetent fails.)
131 - 295 Hilite pattern matches without searching.
129 - 301 Cmd F doesn't repaint on SIGWINCH.
128 - 301 Cmd F doesn't show hilites in new text.
118 - 285 v cmd makes # refer to %
117 - 285 Filename with % or # causes DOS version to crash.
110 - 312 Continue after "cannot reopen" error.
109 - 312 Continue after "read error".
104 - open At end of file while using -s on file with trailing blank lines, prompt may say 99% instead of 100%.
103 - 326 q doesn't always quit (in error()).
101 - open Using -s may display ~ lines before start of file.

Enhancement requests

This is a list of requests for feature enhancements.

Ref number Implemented in version Description
308 open Support proposal for embedding hyperlinks in text files.
307 open Allow the "v" command to edit standard input, by saving the input to a temporary file.
306 504 Add option to display scrolling indicators at end of lines truncated by -S, and at beginning of lines that are scrolled right.
305 open Allow a way to include a numeric prefix on commands in the lesskey file.
303 open When -F is used, don't output terminal initialization and exit sequences when only one screen is displayed.
299 open Add a mode to double-space text, to help distinguish line breaks when wrapped lines are viewed.
298 open Add a mode where the prompt line is not displayed, to add an extra line for file contents.
296 open The -R flag should handle Alternate Character Set sequences in addition to SGR sequences.
285 open In UTF-8 mode in the Windows version, translate UTF-8 characters to the Windows console character set on output.
282 open Support UTF-16 files.
276 open When searching with -S in effect, if matched pattern is scrolled off the right or left edge of the screen, automatically scroll left or right to bring the pattern into view.
275 420 When searching with -S in effect, if matched pattern is scrolled off the right or left edge of the screen, allow status column (-J) to mark the matched line.
275 open Allow fuzzy searching which would match "equivalent" characters like single-quote and curly-single-quote.
272 543 Add support for mouse wheel scrolling.
267 397 Allow syntax in -j option to specify a percentage within the screen rather than an absolute line number.
266 388 Allow compiling a secure version of less via configure options instead of manually editing the defines.h file.
265 389 Allow status column (-J) to mark search matches even if search highlighting is turned off via -G.
263 open Allow prompt to display "screen page" numbers, rather than the "file page" numbers displayed by %d and %D.
259 open Warn if LESSCHARSET conflicts with locale environment variables.
254 381 Add a command line option to disable the LESSOPEN preprocessor.
253 open If a line is so long that it doesn't fit on one screen, a search that finds a match in that line may not be displayed. Display such a search match so that the line is positioned so that the search match is visible.
243 367 Make it easier to install system lesskey file elsewhere.
239 367 Use hash for buffers to improve performance in large files.
235 388 Support real Unicode.
I'm finally satisfied enough with the UTF-8 support in this version that I'm willing to say I support "real Unicode".
234 361 Define POSITION = off_t to help support large files.
232 open Convert docs to Texinfo.
227 351 Make default prompts include top and bottom line number.
225 open Include LESSOPEN filter(s) in distribution. Include a LESSOPEN filter to do C/C++ syntax highlighting.
224 open Make ^L act as screen break.
223 420 Add command to do dynamic line-by-line filtering.
220 363 Support fixed tab stop specifiers.
219 344 -w should highlight target line on g and p commands.
216 343 Prompt should show percent in file based on lines not bytes.
215 343 Change default LESSCHARSET to latin1.
214 343 Support HOME/END keys.
210 415 Allow F command to follow either file descriptor or file name if the input file is renamed.
206 343 Support UTF-8.
197 342 Default system-wide LESSKEY file.
191 337 Enable regular expressions in MS-DOS version.
188 345 Pass thru ANSI color escape sequences.
187 329 Add option to change quote char.
184 open Add "bookmarks" (save marks on exit).
183 334 Document "$" at end of string options better.
182 340 Add command to delete a file from the ifile list.
180 open Add shortcut for lesspipe based on suffix.
177 334 Mark last line from prev screen, like trn -m.
175 322 Add alternate command for ESC-[.
172 open Don't display escape sequences for arrow keys, etc.
169 open Add kludge to get ti/te for xterm on Solaris/SGI.
164 314 Make -e quit immediately on short file.
162 396 Make compatible with POSIX more.
160 307 Use -- to mark end of options.
158 340 Allow special keys (arrows, etc.) in lesskey file.
155 340 Support regexp for DOS.
154 309 Port to OS/9.
153 306 Check for ncurses.
147 310 Embed help file in executable.
133 325 Support spaces in filenames.
132 303 Add forw-screen-force.
130 415 Cmd F doesn't work if file shrinks or is deleted.
124 451 Use GNU regex (ftp.gnu.ai.mit.edu in regex-0.12.tar.gz)
122 open Display in partial screen.
120 304 Turn off regex on individual search.
119 340 Support other standard GNU options.
116 279 Support --help, --version options.
114 278 Check VISUAL before EDITOR.
112 399 Don't move to lowerleft on first screen.
111 313 Support horizontal scrolling.
108 354 Allow configure script to force Spencer regex.
105 334 Add installbin installman to Makefile.
102 open Allow -o for non-pipe input.