LESS(1) BSD Reference Manual LESS(1)
less, more - view files on a CRT
less | more -?
less | more --help
less | more -V
less | more --version
less | more [-[+]aBcCdeEfFgGiIJLmMnNqQrRsSuUVwWX~] [-b space] [-h lines]
[-j line] [-k keyfile] [-o | -O logfile] [-p pattern] [-P prompt]
[-t tag] [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[-# shift] [+[+]cmd] [--] [filename ...]
less is a program similar to the traditional more(1), but which allows
backward movement in the file as well as forward movement. Also, less
does not have to read the entire input file before starting, so with
large input files it starts up faster than text editors like vi(1). less
uses termcap (or terminfo on some systems), so it can run on a variety of
terminals. There is even limited support for hardcopy terminals. (On a
hardcopy terminal, lines which should be printed at the top of the screen
are prefixed with a caret.)
This version of less also acts as more(1) if it is called as more. In
this mode, the differences are in the prompt and that more exits by de-
fault when it gets to the end of the file. Commands are based on both
traditional more and vi(1). Commands may be preceded by a decimal number,
called N in the descriptions below. The number is used by some commands,
as indicated.
In the following descriptions, ^X means control-X. ESC stands for the ES-
CAPE key; for example ESC-v means the two character sequence "ESCAPE",
then "v".
h | H
Help: display a summary of these commands. If you forget all the
other commands, remember this one.
SPACE | ^V | f | ^F
Scroll forward N lines, default one window (see option -z below).
If N is more than the screen size, only the final screenful is
displayed. Warning: some systems use ^V as a special literalization
character.
z Like SPACE, but if N is specified, it becomes the new window size.
ESC-SPACE
Like SPACE, but scrolls a full screensful, even if it reaches end-
of-file in the process.
RETURN | ^N | e | ^E | j | ^J
Scroll forward N lines, default 1. The entire N lines are
displayed, even if N is more than the screen size.
d | ^D
Scroll forward N lines, default one half of the screen size. If N
is specified, it becomes the new default for subsequent d and u
commands.
b | ^B | ESC-v
Scroll backward N lines, default one window (see option -z below).
If N is more than the screen size, only the final screenful is
displayed.
w Like ESC-v, but if N is specified, it becomes the new window size.
y | ^Y | ^P | k | ^K
Scroll backward N lines, default 1. The entire N lines are
displayed, even if N is more than the screen size. Warning: some
systems use ^Y as a special job control character.
u | ^U
Scroll backward N lines, default one half of the screen size. If N
is specified, it becomes the new default for subsequent d and u
commands.
ESC-) | RIGHTARROW
Scroll horizontally right N characters, default half the screen
width (see the -# option). If a number N is specified, it becomes
the default for future RIGHTARROW and LEFTARROW commands. While the
text is scrolled, it acts as though the -S option (chop lines) were
in effect.
ESC-( | LEFTARROW
Scroll horizontally left N characters, default half the screen
width (see the -# option). If a number N is specified, it becomes
the default for future RIGHTARROW and LEFTARROW commands.
r | ^R | ^L
Repaint the screen.
R Repaint the screen, discarding any buffered input. Useful if the
file is changing while it is being viewed.
F Scroll forward, and keep trying to read when the end of file is
reached. Normally this command would be used when already at the
end of the file. It is a way to monitor the tail of a file which is
growing while it is being viewed. (The behavior is similar to the
"tail -f" command.)
g | < | ESC-<
Go to line N in the file, default 1 (beginning of file). (Warning:
this may be slow if N is large.)
G | > | ESC->
Go to line N in the file, default the end of the file. (Warning:
this may be slow if N is large, or if N is not specified and stan-
dard input, rather than a file, is being read.)
p | %
Go to a position N percent into the file. N should be between 0 and
100.
{ If a left curly bracket appears in the top line displayed on the
screen, the { command will go to the matching right curly bracket.
The matching right curly bracket is positioned on the bottom line
of the screen. If there is more than one left curly bracket on the
top line, a number N may be used to specify the N-th bracket on the
line.
} If a right curly bracket appears in the bottom line displayed on
the screen, the } command will go to the matching left curly brack-
et. The matching left curly bracket is positioned on the top line
of the screen. If there is more than one right curly bracket on the
top line, a number N may be used to specify the N-th bracket on the
line.
( Like {, but applies to parentheses rather than curly brackets.
) Like }, but applies to parentheses rather than curly brackets.
[ Like {, but applies to square brackets rather than curly brackets.
] Like }, but applies to square brackets rather than curly brackets.
ESC-^F
Followed by two characters, acts like {, but uses the two charac-
ters as open and close brackets, respectively. For example, "ESC ^F
< >" could be used to go forward to the > which matches the < in
the top displayed line.
ESC-^B
Followed by two characters, acts like }, but uses the two charac-
ters as open and close brackets, respectively. For example, "ESC ^B
< >" could be used to go backward to the < which matches the > in
the bottom displayed line.
m Followed by any lowercase letter, marks the current position with
that letter.
' (Single quote.) Followed by any lowercase letter, returns to the
position which was previously marked with that letter. Followed by
another single quote, returns to the position at which the last
"large" movement command was executed. Followed by a ^ or $, jumps
to the beginning or end of the file respectively. Marks are
preserved when a new file is examined, so the ' command can be used
to switch between input files.
^X^X Same as single quote.
/pattern
Search forward in the file for the N-th line containing the pat-
tern. N defaults to 1. The pattern is a regular expression (see
CAVEATS). The search starts at the second line displayed (but see
the -a and -j options, which change this).
Certain characters are special if entered at the beginning of the
pattern; they modify the type of search rather than become part of
the pattern:
^N | ! Search for lines which do NOT match the pattern.
^E | * Search multiple files. That is, if the search reaches the
END of the current file without finding a match, the search
continues in the next file in the command line list.
^F | @ Begin the search at the first line of the FIRST file in the
command line list, regardless of what is currently
displayed on the screen or the settings of the -a or -j op-
tions.
^K Highlight any text which matches the pattern on the current
screen, but don't move to the first match (KEEP current po-
sition).
^R Don't interpret regular expression metacharacters; that is,
do a simple textual comparison.
?pattern
Search backward in the file for the N-th line containing the pat-
tern. The search starts at the line immediately before the top line
displayed.
Certain characters are special, as in the / command:
^N | ! Search for lines which do NOT match the pattern.
^E | * Search multiple files. That is, if the search reaches the
beginning of the current file without finding a match, the
search continues in the previous file in the command line
list.
^F | @ Begin the search at the last line of the last file in the
command line list, regardless of what is currently
displayed on the screen or the settings of the -a or -j op-
tions.
^K As in forward searches.
^R As in forward searches.
ESC-/pattern
Same as "/*".
ESC-?pattern
Same as "?*".
n Repeat previous search, for N-th line containing the last pattern.
If the previous search was modified by ^N, the search is made for
the N-th line NOT containing the pattern. If the previous search
was modified by ^E, the search continues in the next (or previous)
file if not satisfied in the current file. If the previous search
was modified by ^R, the search is done without using regular ex-
pressions. There is no effect if the previous search was modified
by ^F or ^K.
N Repeat previous search, but in the reverse direction.
ESC-n
Repeat previous search, but crossing file boundaries. The effect is
as if the previous search were modified by *.
ESC-N
Repeat previous search, but in the reverse direction and crossing
file boundaries.
ESC-u
Undo search highlighting. Turn off highlighting of strings matching
the current search pattern. If highlighting is already off because
of a previous ESC-u command, turn highlighting back on. Any search
command will also turn highlighting back on. (Highlighting can also
be disabled by toggling the -G option; in that case search commands
do not turn highlighting back on.)
:e [filename]
Examine a new file. If the filename is missing, the "current" file
(see the :n and :p commands below) from the list of files in the
command line is re-examined. A percent sign (%) in the filename is
replaced by the name of the current file. A pound sign (#) is re-
placed by the name of the previously examined file. However, two
consecutive percent signs are simply replaced with a single percent
sign. This allows you to enter a filename that contains a percent
sign in the name. Similarly, two consecutive pound signs are re-
placed with a single pound sign. The filename is inserted into the
command line list of files so that it can be seen by subsequent :n
and :p commands. If the filename consists of several files, they
are all inserted into the list of files and the first one is exam-
ined. If the filename contains one or more spaces, the entire
filename should be enclosed in double quotes (also see the -" op-
tion).
^X^V | E
Same as :e. Warning: some systems use ^V as a special literaliza-
tion character. On such systems, you may not be able to use ^V.
:n Examine the next file (from the list of files given in the command
line). If a number N is specified, the N-th next file is examined.
:p Examine the previous file in the command line list. If a number N
is specified, the N-th previous file is examined.
:t Go to the specified tag.
:x Examine the first file in the command line list. If a number N is
specified, the N-th file in the list is examined.
:d Remove the current file from the list of files.
t Go to the next tag, if there were more than one matches for the
current tag. See the -t option for more details about tags.
T Go to the previous tag, if there were more than one matches for the
current tag.
= | ^G | :f
Prints some information about the file being viewed, including its
name and the line number and byte offset of the bottom line being
displayed. If possible, it also prints the length of the file, the
number of lines in the file and the percent of the file above the
last displayed line.
- Followed by one of the command line option letters (see OPTIONS
below), this will change the setting of that option and print a
message describing the new setting. If a ^P (CONTROL-P) is entered
immediately after the dash, the setting of the option is changed
but no message is printed. If the option letter has a numeric value
(such as -b or -h), or a string value (such as -P or -t), a new
value may be entered after the option letter. If no new value is
entered, a message describing the current setting is printed and
nothing is changed.
-- Like the - command, but takes a long option name (see OPTIONS
below) rather than a single option letter. You must press RETURN
after typing the option name. A ^P immediately after the second
dash suppresses printing of a message describing the new setting,
as in the - command.
-+ Followed by one of the command line option letters this will reset
the option to its default setting and print a message describing
the new setting. (The "-+X" command does the same thing as "-+X" on
the command line.) This does not work for string-valued options.
--+ Like the -+ command, but takes a long option name rather than a
single option letter.
-! Followed by one of the command line option letters, this will reset
the option to the "opposite" of its default setting and print a
message describing the new setting. This does not work for numeric
or string-valued options.
--! Like the -! command, but takes a long option name rather than a
single option letter.
_ (Underscore.) Followed by one of the command line option letters,
this will print a message describing the current setting of that
option. The setting of the option is not changed.
__ (Double underscore.) Like the _ (underscore) command, but takes a
long option name rather than a single option letter. You must press
RETURN after typing the option name.
+cmd Causes the specified cmd to be executed each time a new file is ex-
amined. For example, +G causes less to initially display each file
starting at the end rather than the beginning.
V Prints the version number of less being run.
q | Q | :q | :Q | ZZ
Exits less.
The following four commands may or may not be valid, depending on your
particular installation.
v Invokes an editor to edit the current file being viewed. The editor
is taken from the environment variable VISUAL, if defined, or
EDITOR if VISUAL is not defined, or defaults to "vi" if neither
VISUAL nor EDITOR is defined. See also the discussion of LESSEDIT
under the section on PROMPTS below.
! shell-command
Invokes a shell to run the shell-command given. A percent sign (%)
in the command is replaced by the name of the current file. A pound
sign (#) is replaced by the name of the previously examined file.
"!!" repeats the last shell command. "!" with no shell command sim-
ply invokes a shell. The shell is taken from the environment vari-
able SHELL, or defaults to "sh".
| <m> shell-command
<m> represents any mark letter. Pipes a section of the input file
to the given shell command. The section of the file to be piped is
between the first line on the current screen and the position
marked by the letter. <m> may also be ^ or $ to indicate beginning
or end of file respectively. If <m> is . or newline, the current
screen is piped.
s filename
Save the input to a file. This only works if the input is a pipe,
not an ordinary file.
Command line options are described below. Most options may be changed
while less is running, via the "-" command.
Most options may be given in one of two forms: either a dash followed by
a single letter, or two dashes followed by a long option name. A long op-
tion name may be abbreviated as long as the abbreviation is unambiguous.
For example, --quit-at-eof may be abbreviated --quit, but not --qui,
since both --quit-at-eof and --quiet begin with --qui. Some long option
names are in uppercase, such as --QUIT-AT-EOF, as distinct from --quit-
at-eof. Such option names need only have their first letter capitalized;
the remainder of the name may be in either case. For example, --Quit-at-
eof is equivalent to --QUIT-AT-EOF.
Options are also taken from the environment variable LESS if the command
is less, or from the environment variable MORE if the command is more.
For example, to avoid typing "less -options ..." each time less is in-
voked, you might tell csh(1):
setenv LESS -options
or if you use sh(1):
LESS="-options"; export LESS
The environment variable is parsed before the command line, so command
line options override the LESS environment variable. If an option appears
in the LESS variable, it can be reset to its default value on the command
line by beginning the command line option with "-+".
For options like -P which take a following string, a dollar sign ($) must
be used to signal the end of the string. For example, to separate a
prompt value from any other options with dollar sign between them:
LESS="-Ps--More--$-C -e"
-? | --help
This option displays a summary of the commands accepted by less
(the same as the h command). (Depending on how your shell inter-
prets the question mark, it may be necessary to quote the question
mark, thus: "-\?".)
-a | --search-skip-screen
Causes searches to start after the last line displayed on the
screen, thus skipping all lines displayed on the screen. By de-
fault, searches start at the second line on the screen (or after
the last found line; see the -j option).
-bn | --buffers=n
Specifies the amount of buffer space less will use for each file,
in units of kilobytes (1024 bytes). By default 64K of buffer space
is used for each file (unless the file is a pipe; see the -B op-
tion). The -b option specifies instead that n kilobytes of buffer
space should be used for each file. If n is -1, buffer space is un-
limited; that is, the entire file is read into memory.
-B | --auto-buffers
By default, when data is read from a pipe, buffers are allocated
automatically as needed. If a large amount of data is read from the
pipe, this can cause a large amount of memory to be allocated. The
-B option disables this automatic allocation of buffers for pipes,
so that only 64K (or the amount of space specified by the -b op-
tion) is used for the pipe. Warning: use of -B can result in er-
roneous display, since only the most recently viewed part of the
file is kept in memory; any earlier data is lost.
-c | --clear-screen
Causes full screen repaints to be painted from the top line down.
By default, full screen repaints are done by scrolling from the
bottom of the screen.
-C | --CLEAR-SCREEN
The -C option is like -c, but the screen is cleared before it is
repainted.
-d | --dumb (less only)
The -d option suppresses the error message normally displayed if
the terminal is dumb; that is, lacks some important capability,
such as the ability to clear the screen or scroll backward. The -d
option does not otherwise change the behavior of less on a dumb
terminal. This option is on by default when invoked as more.
-d (more only)
The -d option causes the default prompt to include the basic direc-
tions ``[Press space to continue, 'q' to quit.]''. The -d option
also causes the message ``[Press 'h' for instructions.]'' to be
displayed when an invalid command is entered (normally, the bell is
rung). This option is useful in environments where users may not be
experienced with pagers.
-e | --quit-at-eof
Causes less to automatically exit the second time it reaches end-
of-file. By default, the only way to exit less is via the "q" com-
mand.
-E | --QUIT-AT-EOF
Causes less to automatically exit the first time it reaches end-of-
file.
-f | --force
Forces non-regular files to be opened. (A non-regular file is a
directory or a device special file.) Also suppresses the warning
message when a binary file is opened. By default, less will refuse
to open non-regular files.
-F | --quit-if-one-screen
Causes less to automatically exit if the entire file can be
displayed on the first screen.
-g | --hilite-search
Normally, less will highlight ALL strings which match the last
search command. The -g option changes this behavior to highlight
only the particular string which was found by the last search com-
mand. This can cause less to run somewhat faster than the default.
-G | --HILITE-SEARCH
The -G option suppresses all highlighting of strings found by
search commands.
-hn | --max-back-scroll=n
Specifies a maximum number of lines to scroll backward. If it is
necessary to scroll backward more than n lines, the screen is
repainted in a forward direction instead. (If the terminal does not
have the ability to scroll backward, -h0 is implied.)
-i | --ignore-case
Causes searches to ignore case; that is, uppercase and lowercase
are considered identical. This option is ignored if any uppercase
letters appear in the search pattern; in other words, if a pattern
contains uppercase letters, then that search does not ignore case.
-I | --IGNORE-CASE
Like -i, but searches ignore case even if the pattern contains up-
percase letters.
-jn | --jump-target=n
Specifies a line on the screen where the "target" line is to be po-
sitioned. A target line is the object of a text search, tag search,
jump to a line number, jump to a file percentage, or jump to a
marked position. The screen line is specified by a number: the top
line on the screen is 1, the next is 2, and so on. The number may
be negative to specify a line relative to the bottom of the screen:
the bottom line on the screen is -1, the second to the bottom is
-2, and so on. If the -j option is used, searches begin at the line
immediately after the target line. For example, if "-j4" is used,
the target line is the fourth line on the screen, so searches begin
at the fifth line on the screen.
-J | --status-column
Displays a status column at the left edge of the screen. The status
column shows the lines that matched the current search. The status
column is also used if the -w or -W option is in effect.
-kfilename | --lesskey-file=filename
Causes less to open and interpret the named file as a lesskey(1)
file. Multiple -k options may be specified. If the LESSKEY or
LESSKEY_SYSTEM environment variable is set, or if a lesskey file is
found in a standard place (see KEY BINDINGS), it is also used as a
lesskey file.
-L | --no-lessopen
Ignore the LESSOPEN environment variable (see the INPUT
PREPROCESSOR section below). This option can be set from within
less, but it will apply only to files opened subsequently, not to
the file which is currently open. When invoked as more, the
LESSOPEN environment variable is ignored by default.
-m | --long-prompt
Causes less to prompt verbosely (like more), with the percent into
the file. By default, less prompts with a colon.
-M | --LONG-PROMPT
Causes less to prompt even more verbosely than more.
-n | --line-numbers
Suppresses line numbers. The default (to use line numbers) may
cause less to run more slowly in some cases, especially with a very
large input file. Suppressing line numbers with the -n option will
avoid this problem. Using line numbers means: the line number will
be displayed in the verbose prompt and in the = command, and the v
command will pass the current line number to the editor (see also
the discussion of LESSEDIT in PROMPTS below).
-N | --LINE-NUMBERS
Causes a line number to be displayed at the beginning of each line
in the display.
-ofilename | --log-file=filename
Causes less to copy its input to the named file as it is being
viewed. This applies only when the input file is a pipe, not an or-
dinary file. If the file already exists, less will ask for confir-
mation before overwriting it.
-Ofilename | --LOG-FILE=filename
The -O option is like -o, but it will overwrite an existing file
without asking for confirmation.
If no log file has been specified, the -o and -O options can be
used from within less to specify a log file. Without a file name,
they will simply report the name of the log file. The "s" command
is equivalent to specifying -o from within less.
-ppattern | --pattern=pattern
The -p option on the command line is equivalent to specifying
+/pattern; that is, it tells less to start at the first occurrence
of pattern in the file.
-Pprompt | --prompt=prompt
Provides a way to tailor the three prompt styles to your own
preference. This option would normally be put in the LESS environ-
ment variable, rather than being typed in with each less command.
Such an option must either be the last option in the LESS variable,
or be terminated by a dollar sign. -Ps followed by a string changes
the default (short) prompt to that string. -Pm changes the medium
(-m) prompt. -PM changes the long (-M) prompt. -Ph changes the
prompt for the help screen. -P= changes the message printed by the
= command. -Pw changes the message printed while waiting for data
(in the F command). All prompt strings consist of a sequence of
letters and special escape sequences. See the section on PROMPTS
for more details.
-q | --quiet | --silent
Causes moderately "quiet" operation: the terminal bell is not rung
if an attempt is made to scroll past the end of the file or before
the beginning of the file. If the terminal has a "visual bell", it
is used instead. The bell will be rung on certain other errors,
such as typing an invalid character. The default is to ring the
terminal bell in all such cases.
-Q | --QUIET | --SILENT
Causes totally "quiet" operation: the terminal bell is never rung.
-r | --raw-control-chars
Causes "raw" control characters to be displayed. The default is to
display control characters using the caret notation; for example, a
control-A (octal 001) is displayed as "^A". Warning: when the -r
option is used, less cannot keep track of the actual appearance of
the screen (since this depends on how the screen responds to each
type of control character). Thus, various display problems may
result, such as long lines being split in the wrong place.
-R | --RAW-CONTROL-CHARS
Like -r, but tries to keep track of the screen appearance where
possible. This works only if the input consists of normal text and
possibly some ANSI "color" escape sequences, which are sequences of
the form:
ESC [ ... m
where the "..." is zero or more characters other than "m". For the
purpose of keeping track of screen appearance, all control charac-
ters and all ANSI color escape sequences are assumed to not move
the cursor. You can make less think that characters other than "m"
can end ANSI color escape sequences by setting the environment
variable LESSANSIENDCHARS to the list of characters which can end a
color escape sequence.
-s | --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a single blank
line. This is useful when viewing nroff(1) output.
-S | --chop-long-lines
Causes lines longer than the screen width to be chopped rather than
folded. That is, the portion of a long line that does not fit in
the screen width is not shown. The default is to fold long lines;
that is, display the remainder on the next line.
-ttag | --tag=tag
The -t option, followed immediately by a TAG, will edit the file
containing that tag. For this to work, tag information must be
available; for example, there may be a file in the current directo-
ry called "tags", which was previously built by ctags(1) or an
equivalent command. If the environment variable LESSGLOBALTAGS is
set, it is taken to be the name of a command compatible with
global, and that command is executed to find the tag. (See
http://www.gnu.org/software/global/global.html). The -t option may
also be specified from within less (using the - command) as a way
of examining a new file. The command ":t" is equivalent to specify-
ing -t from within less.
-Ttagsfile | --tag-file=tagsfile
Specifies a tags file to be used instead of "tags".
-u | --underline-special
Causes backspaces and carriage returns to be treated as printable
characters; that is, they are sent to the terminal when they appear
in the input.
-U | --UNDERLINE-SPECIAL
Causes backspaces, tabs and carriage returns to be treated as con-
trol characters; that is, they are handled as specified by the -r
option.
By default, if neither -u nor -U is given, backspaces which appear
adjacent to an underscore character are treated specially: the
underlined text is displayed using the terminal's hardware under-
lining capability. Also, backspaces which appear between two ident-
ical characters are treated specially: the overstruck text is
printed using the terminal's hardware boldface capability. Other
backspaces are deleted, along with the preceding character. Car-
riage returns immediately followed by a newline are deleted. Other
carriage returns are handled as specified by the -r option. Text
which is overstruck or underlined can be searched for if neither -u
nor -U is in effect.
-V | --version
Displays the version number of less.
-w | --hilite-unread
Temporarily highlights the first "new" line after a forward move-
ment of a full page. The first "new" line is the line immediately
following the line previously at the bottom of the screen. Also
highlights the target line after a g or p command. The highlight is
removed at the next command which causes movement. The entire line
is highlighted, unless the -J option is in effect, in which case
only the status column is highlighted.
-W | --HILITE-UNREAD
Like -w, but temporarily highlights the first new line after any
forward movement command larger than one line.
-xn,... | --tabs=n,...
Sets tab stops. If only one n is specified, tab stops are set at
multiples of n. If multiple values separated by commas are speci-
fied, tab stops are set at those positions, and then continue with
the same spacing as the last two. For example, -x9,17 will set tabs
at positions 9, 17, 25, 33, etc. The default for n is 8.
-X | --no-init
Disables sending the termcap initialization and deinitialization
strings to the terminal. This is sometimes desirable if the deini-
tialization string does something unnecessary, like clearing the
screen.
--no-keypad
Disables sending the keypad initialization and deinitialization
strings to the terminal. This is sometimes useful if the keypad
strings make the numeric keypad behave in an undesirable manner.
-yn | --max-forw-scroll=n
Specifies a maximum number of lines to scroll forward. If it is
necessary to scroll forward more than n lines, the screen is
repainted instead. The -c or -C option may be used to repaint from
the top of the screen if desired. By default, any forward movement
causes scrolling.
-[z]n | --window=n
Changes the default scrolling window size to n lines. The default
is one screenful. The z and w commands can also be used to change
the window size. The "z" may be omitted for compatibility with
more. If the number n is negative, it indicates n lines less than
the current screen size. For example, if the screen is 24 lines,
-z-4 sets the scrolling window to 20 lines. If the screen is
resized to 40 lines, the scrolling window automatically changes to
36 lines.
-cc | --quotes=cc
Changes the filename quoting character. This may be necessary if
you are trying to name a file which contains both spaces and quote
characters. Followed by a single character, this changes the quote
character to that character. Filenames containing a space should
then be surrounded by that character rather than by double quotes.
Followed by two characters, changes the open quote to the first
character, and the close quote to the second character. Filenames
containing a space should then be preceded by the open quote char-
acter and followed by the close quote character. Note that even
after the quote characters are changed, this option remains -" (a
dash followed by a double quote).
-~ | --tilde
Normally lines after end of file are displayed as a single tilde
(~). This option causes lines after end of file to be displayed as
blank lines.
-# | --shift
Specifies the default number of positions to scroll horizontally in
the RIGHTARROW and LEFTARROW commands. If the number specified is
zero, it sets the default number of positions to one half of the
screen width.
-- A command line argument of "--" marks the end of option arguments.
Any arguments following this are interpreted as filenames. This can
be useful when viewing a file whose name begins with a "-" or "+".
+ If a command line option begins with +, the remainder of that op-
tion is taken to be an initial command to less. For example, +G
tells less to start at the end of the file rather than the begin-
ning, and +/xyz tells it to start at the first occurrence of "xyz"
in the file. As a special case, +<number> acts like +<number>g;
that is, it starts the display at the specified line number (howev-
er, see the caveat under the "g" command above). If the option
starts with ++, the initial command applies to every file being
viewed, not just the first one. The + command described previously
may also be used to set (or change) an initial command for every
file.
When entering command line at the bottom of the screen (for example, a
filename for the :e command, or the pattern for a search command), cer-
tain keys can be used to manipulate the command line. Most commands have
an alternate form in [ brackets ] which can be used if a key does not ex-
ist on a particular keyboard. Any of these special keys may be entered
literally by preceding it with the "literal" character, either ^V or ^A.
A backslash itself may also be entered literally by entering two
backslashes.
LEFTARROW [ESC-h]
Move the cursor one space to the left.
RIGHTARROW [ESC-l]
Move the cursor one space to the right.
^LEFTARROW [ESC-b or ESC-LEFTARROW]
(That is, CONTROL and LEFTARROW simultaneously.) Move the cursor
one word to the left.
^RIGHTARROW [ESC-w or ESC-RIGHTARROW]
(That is, CONTROL and RIGHTARROW simultaneously.) Move the cursor
one word to the right.
HOME [ESC-0]
Move the cursor to the beginning of the line.
END [ESC-$]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or cancel the
command if the command line is empty.
DELETE or [ESC-x]
Delete the character under the cursor.
^BACKSPACE [ESC-BACKSPACE]
(That is, CONTROL and BACKSPACE simultaneously.) Delete the word
to the left of the cursor.
^DELETE [ESC-X or ESC-DELETE]
(That is, CONTROL and DELETE simultaneously.) Delete the word
under the cursor.
UPARROW [ESC-k]
Retrieve the previous command line.
DOWNARROW [ESC-j]
Retrieve the next command line.
TAB Complete the partial filename to the left of the cursor. If it
matches more than one filename, the first match is entered into
the command line. Repeated TABs will cycle through the other
matching filenames. If the completed filename is a directory, a
"/" is appended to the filename. The environment variable
LESSSEPARATOR can be used to specify a different character to ap-
pend to a directory name.
BACKTAB [ESC-TAB]
Like TAB, but cycles in the reverse direction through the match-
ing filenames.
^L Complete the partial filename to the left of the cursor. If it
matches more than one filename, all matches are entered into the
command line (if they fit).
^U Delete the entire command line, or cancel the command if the com-
mand line is empty. If you have changed your line-kill character
to something other than ^U, that character is used instead of ^U.
You may define your own less commands by using the program lesskey(1) to
create a lesskey file. This file specifies a set of command keys and an
action associated with each key. You may also use lesskey to change the
line-editing keys (see LINE EDITING), and to set environment variables.
If the environment variable LESSKEY is set, less uses that as the name of
the lesskey file. Otherwise, less looks for a lesskey file called
"$HOME/.less". See the lesskey(1) manual page for more details.
A system-wide lesskey file may also be set up to provide key bindings. If
a key is defined in both a local lesskey file and in the system-wide
file, key bindings in the local file take precedence over those in the
system-wide file. If the environment variable LESSKEY_SYSTEM is set, less
uses that as the name of the system-wide lesskey file. Otherwise, less
looks in a standard place for the system-wide lesskey file: On OpenBSD,
the system-wide lesskey file is /etc/sysless.
You may define an "input preprocessor" for less. Before less opens a
file, it first gives your input preprocessor a chance to modify the way
the contents of the file are displayed. An input preprocessor is simply
an executable program (or shell script), which writes the contents of the
file to a different file, called the replacement file. The contents of
the replacement file are then displayed in place of the contents of the
original file. However, it will appear to the user as if the original
file is opened; that is, less will display the original filename as the
name of the current file.
An input preprocessor receives one command line argument, the original
filename, as entered by the user. It should create the replacement file,
and when finished print the name of the replacement file to its standard
output. If the input preprocessor does not output a replacement filename,
less uses the original file, as normal. The input preprocessor is not
called when viewing standard input. To set up an input preprocessor, set
the LESSOPEN environment variable to a command line which will invoke
your input preprocessor. This command line should include one occurrence
of the string "%s", which will be replaced by the filename when the input
preprocessor command is invoked.
When less closes a file opened in such a way, it will call another pro-
gram, called the input postprocessor, which may perform any desired
clean-up action (such as deleting the replacement file created by
LESSOPEN). This program receives two command line arguments, the original
filename as entered by the user, and the name of the replacement file. To
set up an input postprocessor, set the LESSCLOSE environment variable to
a command line which will invoke your input postprocessor. It may include
two occurrences of the string "%s"; the first is replaced with the origi-
nal name of the file and the second with the name of the replacement
file, which was output by LESSOPEN.
For example, these two scripts will allow you to keep files in compressed
format, but still let less view them directly:
lessopen.sh:
#!/bin/mksh
case "$1" in
*.Z) uncompress -c $1 >/tmp/less.$$ 2>/dev/null
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac
lessclose.sh:
#!/bin/mksh
rm $2
To use these scripts, put them both where they can be executed and set
LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More com-
plex LESSOPEN and LESSCLOSE scripts may be written to accept other types
of compressed files, and so on.
It is also possible to set up an input preprocessor to pipe the file data
directly to less, rather than putting the data into a replacement file.
This avoids the need to decompress the entire file before starting to
view it. An input preprocessor that works this way is called an input
pipe. An input pipe, instead of writing the name of a replacement file on
its standard output, writes the entire contents of the replacement file
on its standard output. If the input pipe does not write any characters
on its standard output, then there is no replacement file and less uses
the original file, as normal. To use an input pipe, make the first char-
acter in the LESSOPEN environment variable a vertical bar (|) to signify
that the input preprocessor is an input pipe.
For example, this script will work like the previous example scripts:
lesspipe.sh:
#!/bin/mksh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
;;
esac
To use this script, put it where it can be executed and set
LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE post-
processor can be used, but it is usually not necessary since there is no
replacement file to clean up. In this case, the replacement file name
passed to the LESSCLOSE postprocessor is "-".
There are three types of characters in the input file:
normal characters Can be displayed directly to the screen.
control characters Should not be displayed directly, but are expected to
be found in ordinary text files (such as backspace
and tab).
binary characters Should not be displayed directly and are not expected
to be found in text files.
A "character set" is simply a description of which characters are to be
considered normal, control, and binary. The LESSCHARSET environment vari-
able may be used to select a character set. Possible values for
LESSCHARSET are:
ascii BS, TAB, NL, CR, and formfeed are control characters, all chars
with values between 32 and 126 are normal, and all others are
binary.
iso8859 Selects an ISO 8859 character set. This is the same as ASCII,
except characters between 160 and 255 are treated as normal
characters.
latin1 Same as iso8859.
latin9 Same as iso8859.
dos Selects a character set appropriate for MS-DOS.
ebcdic Selects an EBCDIC character set.
IBM-1047 Selects an EBCDIC character set used by OS/390 Unix Services.
This is the EBCDIC analogue of latin1. You get similar results
by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in
your environment.
koi8-r Selects a Russian character set.
next Selects a character set appropriate for NeXT computers.
utf-8 Selects the UTF-8 encoding of the ISO 10646 character set.
In special cases, it may be desired to tailor less to use a character set
other than the ones definable by LESSCHARSET. In this case, the environ-
ment variable LESSCHARDEF can be used to define a character set. It
should be set to a string where each character in the string represents
one character in the character set. The character "." is used for a nor-
mal character, "c" for control, and "b" for binary. A decimal number may
be used for repetition. For example, "bccc4b." would mean character 0 is
binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is nor-
mal. All characters after the last are taken to be the same as the last,
so characters 9 through 255 would be normal. (This is an example, and
does not necessarily represent any real character set.)
This table shows the value of LESSCHARDEF which is equivalent to each of
the possible values for LESSCHARSET:
ascii 8bcccbcc18b95.b
dos 8bcccbcc12bc5b95.b.
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
191.b
iso8859 8bcccbcc18b95.33b.
koi8-r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb
If neither LESSCHARSET nor LESSCHARDEF is set, but the string "UTF-8" is
found in the LC_ALL, LC_TYPE or LANG environment variables, then the de-
fault character set is utf-8.
If that string is not found, but your system supports the setlocale in-
terface, less will use setlocale to determine the character set. setlo-
cale is controlled by setting the LANG or LC_CTYPE environment variables.
Finally, if the setlocale interface is also not available, the default
character set is latin1.
Control and binary characters are displayed in standout (reverse video).
Each such character is displayed in caret notation if possible (e.g. ^A
for control-A). Caret notation is used only if inverting the 0100 bit
results in a normal printable character. Otherwise, the character is
displayed as a hex number in angle brackets. This format can be changed
by setting the LESSBINFMT environment variable. LESSBINFMT may begin with
a "*" and one character to select the display attribute: "*k" is blink-
ing, "*d" is bold, "*u" is underlined, "*s" is standout, and "*n" is nor-
mal. If LESSBINFMT does not begin with a "*", normal attribute is as-
sumed. The remainder of LESSBINFMT is a string which may include one
printf-style escape sequence (a % followed by x, X, o, d, etc.). For ex-
ample, if LESSBINFMT is "*u[%x]", binary characters are displayed in
underlined hexadecimal surrounded by brackets. The default if no LESS-
BINFMT is specified is "*s<%X>".
The -P option allows you to tailor the prompt to your preference. The
string given to the -P option replaces the specified prompt string. Cer-
tain characters in the string are interpreted specially. The prompt
mechanism is rather complicated to provide flexibility, but the ordinary
user need not understand the details of constructing personalized prompt
strings.
A percent sign followed by a single character is expanded according to
what the following character is:
%bX Replaced by the byte offset into the current input file. The b is
followed by a single character (shown as X above) which specifies
the line whose byte offset is to be used. If the character is a
"t", the byte offset of the top line in the display is used, an
"m" means use the middle line, a "b" means use the bottom line, a
"B" means use the line just after the bottom line, and a "j"
means use the "target" line, as specified by the -j option.
%B Replaced by the size of the current input file.
%c Replaced by the column number of the text appearing in the first
column of the screen.
%dX Replaced by the page number of a line in the input file. The line
to be used is determined by the X, as with the %b option.
%D Replaced by the number of pages in the input file, or equivalent-
ly, the page number of the last line in the input file.
%E Replaced by the name of the editor (from the VISUAL environment
variable, or the EDITOR environment variable if VISUAL is not de-
fined). See the discussion of the LESSEDIT feature below.
%f Replaced by the name of the current input file.
%i Replaced by the index of the current file in the list of input
files.
%lX Replaced by the line number of a line in the input file. The line
to be used is determined by the X, as with the %b option.
%L Replaced by the line number of the last line in the input file.
%m Replaced by the total number of input files.
%pX Replaced by the percent into the current input file, based on
byte offsets. The line used is determined by the X, as with the
%b option.
%PX Replaced by the percent into the current input file, based on
line numbers. The line used is determined by the X, as with the
%b option.
%s Same as %B.
%t Causes any trailing spaces to be removed. Usually used at the end
of the string, but may appear anywhere.
%x Replaced by the name of the next input file in the list.
If any item is unknown (for example, the file size if input is a pipe), a
question mark is printed instead.
The format of the prompt string can be changed depending on certain con-
ditions. A question mark followed by a single character acts like an
"IF": depending on the following character, a condition is evaluated. If
the condition is true, any characters following the question mark and
condition character, up to a period, are included in the prompt. If the
condition is false, such characters are not included. A colon appearing
between the question mark and the period can be used to establish an
"ELSE": any characters between the colon and the period are included in
the string, if and only if the IF condition is false. Condition charac-
ters (which follow a question mark) may be:
?a True if any characters have been included in the prompt so far.
?bX True if the byte offset of the specified line is known.
?B True if the size of the current input file is known.
?c True if the text is horizontally shifted (%c is not zero).
?dX True if the page number of the specified line is known.
?e True if at end-of-file.
?f True if there is an input filename (that is, if input is not a
pipe).
?lX True if the line number of the specified line is known.
?L True if the line number of the last line in the file is known.
?m True if there is more than one input file.
?n True if this is the first prompt in a new input file.
?pX True if the percent into the current input file, based on byte
offsets, of the specified line is known.
?PX True if the percent into the current input file, based on line
numbers, of the specified line is known.
?s Same as "?B".
?x True if there is a next input file (that is, if the current input
file is not the last one).
Any characters other than the special ones (question mark, colon, period,
percent, and backslash) become literally part of the prompt. Any of the
special characters may be included in the prompt literally by preceding
it with a backslash.
Some examples:
?f%f:Standard input.
This prompt prints the filename, if known; otherwise the string "Standard
input".
?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
This prompt would print the filename, if known. The filename is followed
by the line number, if known, otherwise the percent if known, otherwise
the byte offset if known. Otherwise, a dash is printed. Notice how each
question mark has a matching period, and how the % after the %pt is in-
cluded literally by escaping it with a backslash.
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t
This prints the filename if this is the first prompt in a file, followed
by the "file N of N" message if there is more than one input file. Then,
if we are at end-of-file, the string "(END)" is printed followed by the
name of the next file, if there is one. Finally, any trailing spaces are
truncated. This is the default prompt. For reference, here are the de-
faults for the other two prompts (-m and -M respectively). Each is broken
into two lines here for readability only.
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
?pB%pB\%:byte %bB?s/%s...%t
?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
And here is the default message produced by the = command:
?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
The prompt expansion features are also used for another purpose: if an
environment variable LESSEDIT is defined, it is used as the command to be
executed when the v command is invoked. The LESSEDIT string is expanded
in the same way as the prompt strings. The default value for LESSEDIT is:
%E ?lm+%lm. %f
Note that this expands to the editor name, followed by a + and the line
number, followed by the file name. If your editor does not accept the
"+linenumber" syntax, or has other differences in invocation syntax, the
LESSEDIT variable can be changed to modify this default.
When the environment variable LESSSECURE is set to 1, less runs in a
"secure" mode. This means these features are disabled:
! The shell command.
| The pipe command.
:e The examine command.
v The editing command.
s -o Log files.
-k Use of lesskey files.
-t Use of tags files.
Metacharacters in filenames, such as "*".
Filename completion (TAB, ^L).
Less can also be compiled to be permanently in "secure" mode.
Environment variables may be specified either in the system environment
as usual, or in a lesskey(1) file. If environment variables are defined
in more than one place, variables defined in a local lesskey file take
precedence over variables defined in the system environment, which take
precedence over variables defined in the system-wide lesskey file.
COLUMNS
Sets the number of columns on the screen. Takes precedence over
the number of columns specified by the TERM variable. (But if you
have a windowing system which supports TIOCGWINSZ or WIOCGETD,
the window system's idea of the screen size takes precedence over
the LINES and COLUMNS environment variables.)
EDITOR The name of the editor (used for the v command).
HOME Name of the user's home directory (used to find a lesskey file).
LANG Language for determining the character set.
LC_CTYPE
Language for determining the character set.
LESS Options which are passed to less automatically.
LESSANSIENDCHARS
Characters which are assumed to end an ANSI color escape sequence
(default "m").
LESSBINFMT
Format for displaying non-printable, non-control characters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSCLOSE
Command line to invoke the (optional) input-postprocessor.
LESSEDIT
Editor prototype string (used for the v command). See discussion
under PROMPTS.
LESSGLOBALTAGS
Name of the command used by the -t option to find global tags.
Normally should be set to "global" if your system has the global
command. If not set, global tags are not used.
LESSKEY
Name of the default lesskey(1) file.
LESSKEY_SYSTEM
Name of the default system-wide lesskey(1) file.
LESSMETACHARS
List of characters which are considered "metacharacters" by the
shell.
LESSMETAESCAPE
Prefix which less will add before each metacharacter in a command
sent to the shell. If LESSMETAESCAPE is an empty string, commands
containing metacharacters will not be passed to the shell.
LESSOPEN
Command line to invoke the (optional) input-preprocessor.
LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.
LESSSEPARATOR
String to be appended to a directory name in filename completion.
LINES Sets the number of lines on the screen. Takes precedence over the
number of lines specified by the TERM variable. (But if you have
a windowing system which supports TIOCGWINSZ or WIOCGETD, the
window system's idea of the screen size takes precedence over the
LINES and COLUMNS environment variables.)
SHELL The shell used to execute the ! command, as well as to expand
filenames.
TERM The type of terminal on which less is being run.
VISUAL The name of the editor (used for the v command).
lesskey(1)
Copyright (C) 2002 Mark Nudelman <markn@greenwoodsoftware.com>
Send bug reports or comments to the above address or to
<bug-less@gnu.org>.
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.
The regular expression dialect understood by less depends on compile-time
options and the operating system. It may use POSIX EREs, BREs or a
slightly extended BRE variant. On MirBSD, it's EREs, currently.
The = command and prompts (unless changed by -P) report the line numbers
of the lines at the top and bottom of the screen, but the byte and per-
cent of the line after the one at the bottom of the screen.
If the :e command is used to name more than one file, and one of the
named files has been viewed previously, the new files may be entered into
the list in an unexpected order.
On certain older terminals (the so-called "magic cookie" terminals),
search highlighting will cause an erroneous display. On such terminals,
search highlighting is disabled by default to avoid possible problems.
In certain cases, when search highlighting is enabled and a search pat-
tern begins with a ^, more text than the matching string may be
highlighted. (This problem does not occur when less is compiled to use
the POSIX regular expression package.)
When viewing text containing ANSI color escape sequences using the -R op-
tion, searching will not find text containing an embedded escape se-
quence. Also, search highlighting may change the color of some of the
text which follows the highlighted text.
On some systems, setlocale claims that ASCII characters 0 through 31 are
control characters rather than binary characters. This causes less to
treat some binary files as ordinary, non-binary files. To workaround this
problem, set the environment variable LESSCHARSET to "ascii" (or whatever
character set is appropriate).
See http://www.greenwoodsoftware.com/less for the latest list of known
bugs in this version of less.
MirBSD #10-current December 3, 2022 21