LESS(1) General Commands Manual LESS(1)
NAME
less - opposite of more
SYNOPSIS
less -?
less --help
less -V
less --version
less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[-# shift] [+[+]cmd] [--] [filename]...
(See the OPTIONS section for alternate option syntax with long option names.)
DESCRIPTION
Less is a program similar to more (1), but which allows backward movement in the file as well as forward move‐
ment. 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 termi‐
nal, lines which should be printed at the top of the screen are prefixed with a caret.)
Commands are based on both more and vi. Commands may be preceded by a decimal number, called N in the
descriptions below. The number is used by some commands, as indicated.
COMMANDS
In the following descriptions, ^X means control-X. ESC stands for the ESCAPE key; for example ESC-v means the
two character sequence "ESCAPE", then "v".
h or H Help: display a summary of these commands. If you forget all the other commands, remember this one.
SPACE or ^V or f or ^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 char‐
acter.
z Like SPACE, but if N is specified, it becomes the new window size.
ESC-SPACE
Like SPACE, but scrolls a full screenful, even if it reaches end-of-file in the process.
ENTER or RETURN or ^N or e or ^E or j or ^J
Scroll forward N lines, default 1. The entire N lines are displayed, even if N is more than the screen
size.
d or ^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 or ^B or 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.
scrolled, it acts as though the -S option (chop lines) were in effect.
ESC-( or 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 or ^R or ^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 grow‐
ing while it is being viewed. (The behavior is similar to the "tail -f" command.)
ESC-F Like F, but as soon as a line is found which matches the last search pattern, the terminal bell is rung
and forward scrolling stops.
g or < or ESC-<
Go to line N in the file, default 1 (beginning of file). (Warning: this may be slow if N is large.)
G or > or 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 standard input, rather than a file, is being read.)
p or % Go to a position N percent into the file. N should be between 0 and 100, and may contain a decimal
point.
P Go to the line containing byte offset N in the file.
{ 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 spec‐
ify 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 bracket. 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 spec‐
ify 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 characters 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 characters as open and close brackets,
/pattern
Search forward in the file for the N-th line containing the pattern. N defaults to 1. The pattern is
a regular expression, as recognized by the regular expression library supplied by your system. The
search starts at the first 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 or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search reaches the END of the current file without find‐
ing a match, the search continues in the next file in the command line list.
^F or @
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 options.
^K Highlight any text which matches the pattern on the current screen, but don't move to the first
match (KEEP current position).
^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 pattern. The search starts at the line
immediately before the top line displayed.
Certain characters are special as in the / command:
^N or !
Search for lines which do NOT match the pattern.
^E or *
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 or @
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 options.
^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
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.)
&pattern
Display only lines which match the pattern; lines which do not match the pattern are not displayed. If
pattern is empty (if you type & immediately followed by ENTER), any filtering is turned off, and all
lines are displayed. While filtering is in effect, an ampersand is displayed at the beginning of the
prompt, as a reminder that some lines in the file may be hidden.
Certain characters are special as in the / command:
^N or !
Display only lines which do NOT match the pattern.
^R Don't interpret regular expression metacharacters; that is, do a simple textual comparison.
: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 replaced 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 consecu‐
tive pound signs are replaced 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 examined. If the
filename contains one or more spaces, the entire filename should be enclosed in double quotes (also see
the -" option).
^X^V or E
Same as :e. Warning: some systems use ^V as a special literalization 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.
: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.
= or ^G or :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.
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 sin‐
gle option letter. You must press ENTER or RETURN after typing the option name.
+cmd Causes the specified cmd to be executed each time a new file is examined. 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 or Q or :q or :Q or 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 simply invokes a shell. On Unix sys‐
tems, the shell is taken from the environment variable SHELL, or defaults to "sh". On MS-DOS and OS/2
systems, the shell is the normal command processor.
| <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.
OPTIONS
Command line options are described below. Most options may be changed while less is running, via the "-" com‐
mand.
Most options may be given in one of two forms: either a dash followed by a single letter, or two dashes fol‐
lowed by a long option name. A long option name may be abbreviated as long as the abbreviation is unambigu‐
ous. For example, --quit-at-eof may be abbreviated --quit, but not --qui, since both --quit-at-eof and
On MS-DOS, you don't need the quotes, but you should replace any percent signs in the options string by double
percent signs.
The environment variable is parsed before the command line, so command line options override the LESS environ‐
ment 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 "-+".
Some options like -k or -D require a string to follow the option letter. The string for that option is con‐
sidered to end when a dollar sign ($) is found. For example, you can set two -D options on MS-DOS like this:
LESS="Dn9.1$Ds4.1"
If the --use-backslash option appears earlier in the options, then a dollar sign or backslash may be included
literally in an option string by preceding it with a backslash. If the --use-backslash option is not in
effect, then backslashes are not treated specially, and there is no way to include a dollar sign in the option
string.
-? or --help
This option displays a summary of the commands accepted by less (the same as the h command). (Depend‐
ing on how your shell interprets the question mark, it may be necessary to quote the question mark,
thus: "-\?".)
-a or --search-skip-screen
By default, forward searches start at the top of the displayed screen and backwards searches start at
the bottom of the displayed screen (except for repeated searches invoked by the n or N commands, which
start after or before the "target" line respectively; see the -j option for more about the target
line). The -a option causes forward searches to instead start at the bottom of the screen and backward
searches to start at the top of the screen, thus skipping all lines displayed on the screen.
-A or --SEARCH-SKIP-SCREEN
Causes all forward searches (not just non-repeated searches) to start just after the target line, and
all backward searches to start just before the target line. Thus, forward searches will skip part of
the displayed screen (from the first line up to and including the target line). Similarly backwards
searches will skip the displayed screen from the last line up to and including the target line. This
was the default behavior in less versions prior to 441.
-bn or --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 option).
The -b option specifies instead that n kilobytes of buffer space should be used for each file. If n is
-1, buffer space is unlimited; that is, the entire file can be read into memory.
-B or --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 option) is used for the pipe. Warning: use of -B can result in erroneous
display, since only the most recently viewed part of the piped data is kept in memory; any earlier data
is lost.
-c or --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.
numbers separated by a period. The first number selects the foreground color and the second selects
the background color of the text. A single number N is the same as N.M, where M is the normal back‐
ground color.
-e or --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" command.
-E or --QUIT-AT-EOF
Causes less to automatically exit the first time it reaches end-of-file.
-f or --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. Note that some operating systems will not allow directories to be read, even if -f
is set.
-F or --quit-if-one-screen
Causes less to automatically exit if the entire file can be displayed on the first screen.
-g or --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 command. This
can cause less to run somewhat faster than the default.
-G or --HILITE-SEARCH
The -G option suppresses all highlighting of strings found by search commands.
--old-bot
Reverts to the old bottom of screen behavior. This can be sometimes desirable if the long lines are
not wrapped correctly when reaching the bottom of the terminal, while scrolling forward.
-hn or --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 or --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 or --IGNORE-CASE
Like -i, but searches ignore case even if the pattern contains uppercase letters.
-jn or --jump-target=n
Specifies a line on the screen where the "target" line is to be positioned. The target line is the
line specified by any command to search for a pattern, jump to a line number, jump to a file percentage
or jump to a tag. The screen line may be 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. Alternately,
the screen line may be specified as a fraction of the height of the screen, starting with a decimal
point: .5 is in the middle of the screen, .3 is three tenths down from the first line, and so on. If
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.
-K or --quit-on-intr
Causes less to exit immediately (with status 2) when an interrupt character (usually ^C) is typed.
Normally, an interrupt character causes less to stop whatever it is doing and return to its command
prompt. Note that use of this option makes it impossible to return to the command prompt from the "F"
command.
-L or --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.
-m or --long-prompt
Causes less to prompt verbosely (like more), with the percent into the file. By default, less prompts
with a colon.
-M or --LONG-PROMPT
Causes less to prompt even more verbosely than more.
-n or --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 discus‐
sion of LESSEDIT in PROMPTS below).
-N or --LINE-NUMBERS
Causes a line number to be displayed at the beginning of each line in the display.
-ofilename or --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 ordinary file. If the file already exists, less will ask for confirmation
before overwriting it.
-Ofilename or --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 or --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 or --prompt=prompt
Provides a way to tailor the three prompt styles to your own preference. This option would normally be
put in the LESS environment 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
-r or --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 or --RAW-CONTROL-CHARS
Like -r, but only ANSI "color" escape sequences are output in "raw" form. Unlike -r, the screen
appearance is maintained correctly in most cases. ANSI "color" escape sequences are sequences of the
form:
ESC [ ... m
where the "..." is zero or more color specification characters For the purpose of keeping track of
screen appearance, 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. And you can
make less think that characters other than the standard ones may appear between the ESC and the m by
setting the environment variable LESSANSIMIDCHARS to the list of characters which can appear.
-s or --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a single blank line. This is useful when viewing
nroff output.
-S or --chop-long-lines
Causes lines longer than the screen width to be chopped (truncated) rather than wrapped. That is, the
portion of a long line that does not fit in the screen width is not shown. The default is to wrap long
lines; that is, display the remainder on the next line.
-ttag or --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 directory
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 (1), 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 specifying -t from within less.
-Ttagsfile or --tag-file=tagsfile
Specifies a tags file to be used instead of "tags".
-u or --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 or --UNDERLINE-SPECIAL
Causes backspaces, tabs and carriage returns to be treated as control 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 underlining capa‐
bility. Also, backspaces which appear between two identical characters are treated specially: the
causes movement. The entire line is highlighted, unless the -J option is in effect, in which case only
the status column is highlighted.
-W or --HILITE-UNREAD
Like -w, but temporarily highlights the first new line after any forward movement command larger than
one line.
-xn,... or --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 specified, 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 or --no-init
Disables sending the termcap initialization and deinitialization strings to the terminal. This is
sometimes desirable if the deinitialization string does something unnecessary, like clearing the
screen.
-yn or --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 or --window=n
Changes the default scrolling window size to n lines. The default is one screenful. The z and w com‐
mands can also be used to change the window size. The "z" may be omitted for compatibility with some
versions of 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 or --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 charac‐
ter, and the close quote to the second character. Filenames containing a space should then be preceded
by the open quote character 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).
-~ or --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.
-# or --shift
Specifies the default number of positions to scroll horizontally in the RIGHTARROW and LEFTARROW com‐
mands. If the number specified is zero, it sets the default number of positions to one half of the
screen width. Alternately, the number may be specified as a fraction of the width of the screen,
starting with a decimal point: .5 is half of the screen width, .3 is three tenths of the screen width,
and so on. If the number is specified as a fraction, the actual number of scroll positions is recalcu‐
lated if the terminal window is resized, so that the actual scroll remains at the specified fraction of
the screen width.
--follow-name
Normally, if the input file is renamed while an F command is executing, less will continue to display
This allows a dollar sign to be included in option strings.
-- 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 option 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 beginning, 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 (however, 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.
LINE EDITING
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), certain 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 exist on a particular keyboard. (Note that
the forms beginning with ESC do not work in some MS-DOS and Windows systems because ESC is the line erase
character.) 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. If you first enter some text and then press UPARROW, it will
BACKTAB [ ESC-TAB ]
Like, TAB, but cycles in the reverse direction thru the matching 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 (Unix and OS/2) or ESC (MS-DOS)
Delete the entire command line, or cancel the command if the command line is empty. If you have
changed your line-kill character in Unix to something other than ^U, that character is used instead of
^U.
^G Delete the entire command line and return to the main prompt.
KEY BINDINGS
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 in a standard place for
the lesskey file: On Unix systems, less looks for a lesskey file called "$HOME/.less". On MS-DOS and Windows
systems, less looks for a lesskey file called "$HOME/_less", and if it is not found there, then looks for a
lesskey file called "_less" in any directory specified in the PATH environment variable. On OS/2 systems,
less looks for a lesskey file called "$HOME/less.ini", and if it is not found, then looks for a lesskey file
called "less.ini" in any directory specified in the INIT environment variable, and if it not found there, then
looks for a lesskey file called "less.ini" in any directory specified in the PATH environment variable. See
the lesskey 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 sys‐
tem-wide lesskey file. Otherwise, less looks in a standard place for the system-wide lesskey file: On Unix
systems, the system-wide lesskey file is /usr/local/etc/sysless. (However, if less was built with a different
sysconf directory than /usr/local/etc, that directory is where the sysless file is found.) On MS-DOS and Win‐
dows systems, the system-wide lesskey file is c:\_sysless. On OS/2 systems, the system-wide lesskey file is
c:\sysless.ini.
INPUT PREPROCESSOR
You may define an "input preprocessor" for less. Before less opens a file, it first gives your input pre‐
processor 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 dis‐
play 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 com‐
mand 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 program, called the input postprocessor,
case "$1" in
*.Z) uncompress -
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac
lessclose.sh:
#! /bin/sh
rm $2
To use these scripts, put them both where they can be executed and set LESSOPEN="lessopen.sh %s", and LESS‐
CLOSE="lessclose.sh %s %s". More complex 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
character in the LESSOPEN environment variable a vertical bar (|) to signify that the input preprocessor is an
input pipe.
For example, on many Unix systems, this script will work like the previous example scripts:
lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
*) exit 1
;;
esac
exit $?
To use this script, put it where it can be executed and set LESSOPEN="|lesspipe.sh %s".
Note that a preprocessor cannot output an empty file, since that is interpreted as meaning there is no
replacement, and the original file is used. To avoid this, if LESSOPEN starts with two vertical bars, the
exit status of the script becomes meaningful. If the exit status is zero, the output is considered to be
replacement text, even if it empty. If the exit status is nonzero, any output is ignored and the original
file is used. For compatibility with previous versions of less, if LESSOPEN starts with only one vertical
bar, the exit status of the preprocessor is ignored.
When an input pipe is used, a LESSCLOSE postprocessor 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 postpro‐
cessor is "-".
For compatibility with previous versions of less, the input preprocessor or pipe is not used if less is view‐
ing standard input. However, if the first character of LESSOPEN is a dash (-), the input preprocessor is used
on standard input as well as other files. In this case, the dash is not considered to be part of the pre‐
NATIONAL CHARACTER SETS
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 variable 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 nor‐
mal, 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. UTF-8 is special in that it supports multi-
byte characters in the input file. It is the only character set that supports multi-byte characters.
windows
Selects a character set appropriate for Microsoft Windows (cp 1251).
In rare cases, it may be desired to tailor less to use a character set other than the ones definable by LESS‐
CHARSET. In this case, the environment 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 normal 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 normal. All characters after the last are taken to be the same as the last, so
koi8-r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb
If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings "UTF-8", "UTF8", "utf-8" or "utf8" is
found in the LC_ALL, LC_CTYPE or LANG environment variables, then the default character set is utf-8.
If that string is not found, but your system supports the setlocale interface, less will use setlocale to
determine the character set. setlocale 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 blinking, "*d" is bold, "*u" is under‐
lined, "*s" is standout, and "*n" is normal. If LESSBINFMT does not begin with a "*", normal attribute is
assumed. The remainder of LESSBINFMT is a string which may include one printf-style escape sequence (a % fol‐
lowed by x, X, o, d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters are displayed in under‐
lined hexadecimal surrounded by brackets. The default if no LESSBINFMT is specified is "*s<%02X>". Warning:
the result of expanding the character via LESSBINFMT must be less than 31 characters.
When the character set is utf-8, the LESSUTFBINFMT environment variable acts similarly to LESSBINFMT but it
applies to Unicode code points that were successfully decoded but are unsuitable for display (e.g., unassigned
code points). Its default value is "<U+%04lX>". Note that LESSUTFBINFMT and LESSBINFMT share their display
attribute setting ("*x") so specifying one will affect both; LESSUTFBINFMT is read after LESSBINFMT so its
setting, if any, will have priority. Problematic octets in a UTF-8 file (octets of a truncated sequence,
octets of a complete but non-shortest form sequence, illegal octets, and stray trailing octets) are displayed
individually using LESSBINFMT so as to facilitate diagnostic of how the UTF-8 file is ill-formed.
PROMPTS
The -P option allows you to tailor the prompt to your preference. The string given to the -P option replaces
the specified prompt string. Certain characters in the string are interpreted specially. The prompt mecha‐
nism 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 equivalently, the page number of the last line in
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 deter‐
mined 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 deter‐
mined 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 any‐
where.
%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 conditions. 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 characters
(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 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.
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, other‐
wise 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 included 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 defaults 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.
SECURITY
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
If the environment variable LESS_IS_MORE is set to 1, or if the program is invoked via a file link named
"more", less behaves (mostly) in conformance with the POSIX "more" command specification. In this mode, less
behaves differently in these ways:
The -e option works differently. If the -e option is not set, less behaves as if the -E option were set. If
the -e option is set, less behaves as if the -e and -F options were set.
The -m option works differently. If the -m option is not set, the medium prompt is used, and it is prefixed
with the string "--More--". If the -m option is set, the short prompt is used.
The -n option acts like the -z option. The normal behavior of the -n option is unavailable in this mode.
The parameter to the -p option is taken to be a less command rather than a search pattern.
The LESS environment variable is ignored, and the MORE environment variable is used in its place.
ENVIRONMENT VARIABLES
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 on Unix and OS/2 systems).
HOMEDRIVE, HOMEPATH
Concatenation of the HOMEDRIVE and HOMEPATH environment variables is the name of the user's home direc‐
tory if the HOME variable is not set (only in the Windows version).
INIT Name of the user's init directory (used to find a lesskey file on OS/2 systems).
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 may end an ANSI color escape sequence (default "m").
LESSANSIMIDCHARS
Characters which may appear between the ESC character and the end character in an ANSI color escape
sequence (default "0123456789;[?!"'#%()*+ ".
LESSBINFMT
Format for displaying non-printable, non-control characters.
acters, such as * and ?, in filenames on Unix systems.
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 (1) command. If not set, global tags are not used.
LESSHISTFILE
Name of the history file used to remember search commands and shell commands between invocations of
less. If set to "-" or "/dev/null", a history file is not used. The default is "$HOME/.lesshst" on
Unix systems, "$HOME/_lesshst" on DOS and Windows systems, or "$HOME/lesshst.ini" or
"$INIT/lesshst.ini" on OS/2 systems.
LESSHISTSIZE
The maximum number of commands to save in the history file. The default is 100.
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.
LESSUTFBINFMT
Format for displaying non-printable Unicode code points.
LESS_IS_MORE
Emulate the more (1) command.
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.)
MORE Options which are passed to less automatically when running in more compatible mode.
PATH User's search path (used to find a lesskey file on MS-DOS and OS/2 systems).
Copyright (C) 1984-2012 Mark Nudelman
less is part of the GNU project and is free software. You can redistribute it and/or modify it under the
terms of either (1) the GNU General Public License as published by the Free Software Foundation; or (2) the
Less License. See the file README in the less distribution for more details regarding redistribution. You
should have received a copy of the GNU General Public License along with the source for less; see the file
COPYING. If not, write to the Free Software Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307,
USA. You should also have received a copy of the Less License; see the file LICENSE.
less is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
AUTHOR
Mark Nudelman
Send bug reports or comments to <[email protected]>
See http://www.greenwoodsoftware.com/less/bugs.html for the latest list of known bugs in less.
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.
Version 458: 04 Apr 2013 LESS(1)
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