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LESS(1) General Commands Manual LESS(1)
less - opposite of more
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.)
Less is a program similar to 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.)
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.
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 character.
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.
y or ^Y or ^P or k or ^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 or ^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.
J Like j, but continues to scroll beyond the end of the
file.
K or Y Like k, but continues to scroll beyond the beginning of
the file.
ESC-) or 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-( 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.
ESC-} or ^RIGHTARROW
Scroll horizontally right to show the end of the longest
displayed line.
ESC-{ or ^LEFTARROW
Scroll horizontally left back to the first column.
r or ^R or ^L
Repaint the screen.
R Repaint the screen, discarding any buffered input. That
is, reload the current file. 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.) To stop waiting for more data, enter the
interrupt character (usually ^C). On systems which
support poll(2) you can also use ^X or the character
specified by the --intr option. If the input is a pipe
and the --exit-follow-on-close option is in effect, less
will automatically stop waiting for data when the input
side of the pipe is closed.
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.)
ESC-G Same as G, except if no number N is specified and the
input is standard input, goes to the last line which is
currently buffered.
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 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 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 bottom
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
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, 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 or uppercase letter, marks the
first displayed line with that letter. If the status
column is enabled via the -J option, the status column
shows the marked line.
M Acts like m, except the last displayed line is marked
rather than the first displayed line.
' (Single quote.) Followed by any lowercase or uppercase
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.
ESC-m Followed by any lowercase or uppercase letter, clears the
mark identified by that letter.
/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. By default, searching is
case-sensitive (uppercase and lowercase are considered
different); the -i option can be used to change this. 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 finding
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.
^S Followed by a digit N between 1 and 5. Only text
which has a non-empty match for the N-th
parenthesized SUB-PATTERN will be considered to
match the pattern. (Supported only if less is
built with one of the regular expression libraries
posix, pcre, or pcre2.) Multiple ^S modifiers can
be specified, to match more than one sub-pattern.
^W WRAP around the current file. That is, if the
search reaches the end of the current file without
finding a match, the search continues from the
first line of the current file up to the line where
it started. If the ^W modifier is set, the ^E
modifier is ignored.
?pattern
Search backward in the file for the N-th line containing
the pattern. The search starts at the last line displayed
(but see the -a and -j options, which change this).
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.
^S As in forward searches.
^W WRAP around the current file. That is, if the
search reaches the beginning of the current file
without finding a match, the search continues from
the last line of the current file up to the line
where it started.
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
expressions. 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.)
ESC-U Like ESC-u but also clears the saved search pattern. If
the status column is enabled via the -J option, this
clears all search matches marked in the status column.
&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. Multiple & commands may be
entered, in which case only lines which match all of the
patterns will be displayed.
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
consecutive 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.
- 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 ENTER or 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 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 six 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 systems, 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.
# shell-command
Similar to the "!" command, except that the command is
expanded in the same way as prompt strings. For example,
the name of the current file would be given as "%f".
| <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 position marked by the
letter and the current screen. The entire current screen
is included, regardless of whether the marked position is
before or after the current screen. <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 works only if the input is
a pipe, not an ordinary file.
^X When the "Waiting for data" message is displayed, such as
while in the F command, pressing ^X will stop less from
waiting and return to a prompt. This may cause less to
think that the file ends at the current position, so it
may be necessary to use the R or F command to see more
data. The --intr option can be used to specify a
different character to use instead of ^X. This command
works only on systems that support the poll(2) function.
On systems without poll(2), the interrupt character
(usually ^C) can be used instead.
Command line options are described below. Most options may be
changed while less is running, via the "-" command.
Some 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 option 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". For
example, to avoid typing "less -options ..." each time less is
invoked, you might tell csh:
setenv LESS "-options"
or if you use sh:
LESS="-options"; export LESS
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 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 "-+".
Some options like -k or -D require a string to follow the option
letter. The string for that option is considered to end when a
dollar sign ($) is found. For example, you can set two -D
options like this:
LESS="Dn9.1$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). (Depending 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
64 KB 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
64 KB (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. Lost characters are displayed as question marks.
-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.
-C or --CLEAR-SCREEN
Same as -c, for compatibility with older versions of less.
-d or --dumb
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.
-Dxcolor or --color=xcolor
Changes the color of different parts of the displayed
text. x is a single character which selects the type of
text whose color is being set:
B Binary characters.
C Control characters.
E Errors and informational messages.
H Header lines and columns, set via the --header
option.
M Mark letters in the status column.
N Line numbers enabled via the -N option.
P Prompts.
R The rscroll character.
S Search results.
1-5 The text in a search result which matches the first
through fifth parenthesized sub-pattern. Sub-
pattern coloring works only if less is built with
one of the regular expression libraries posix,
pcre, or pcre2.
W The highlight enabled via the -w option.
d Bold text.
k Blinking text.
s Standout text.
u Underlined text.
The uppercase letters and digits can be used only when the
--use-color option is enabled. When text color is
specified by both an uppercase letter and a lowercase
letter, the uppercase letter takes precedence. For
example, error messages are normally displayed as standout
text. So if both "s" and "E" are given a color, the "E"
color applies to error messages, and the "s" color applies
to other standout text. The "d" and "u" letters refer to
bold and underline text formed by overstriking with
backspaces (see the -U option), not to text using ANSI
escape sequences with the -R option.
A lowercase letter may be followed by a + to indicate that
the normal format change and the specified color should
both be used. For example, -Dug displays underlined text
as green without underlining; the green color has replaced
the usual underline formatting. But -Du+g displays
underlined text as both green and in underlined format.
color is either a 4-bit color string or an 8-bit color
string:
A 4-bit color string is zero, one or two characters, where
the first character specifies the foreground color and the
second specifies the background color as follows:
b Blue
c Cyan
g Green
k Black
m Magenta
r Red
w White
y Yellow
The corresponding uppercase letter denotes a brighter
shade of the color. For example, -DNGk displays line
numbers as bright green text on a black background, and
-DEbR displays error messages as blue text on a bright red
background. If either character is a "-" or is omitted,
the corresponding color is set to that of normal text.
An 8-bit color string is one or two decimal integers
separated by a dot, where the first integer specifies the
foreground color and the second specifies the background
color. Each integer is a value between 0 and 255
inclusive which selects a "CSI 38;5" color value (see
https://en.wikipedia.org/wiki/ANSI_escape_code#SGR) If ei‐
ther integer is a "-" or is omitted, the corresponding
color is set to that of normal text. On MS-DOS versions
of less, 8-bit color is not supported; instead, decimal
values are interpreted as 4-bit CHAR_INFO.Attributes val‐
ues (see
https://docs.microsoft.com/en-us/windows/console/char-info-str).
On MS-DOS only, the -Da option may be used to specify
strict parsing of ANSI color (SGR) sequences when the -R
option is used. Without this option, sequences that
change text attributes (bold, underline, etc.) may clear
the text 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 reach‐
es 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 sup‐
presses 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 directo‐
ries 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 some‐
what faster than the default.
-G or --HILITE-SEARCH
The -G option suppresses all highlighting of strings found
by search commands.
-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 back‐
ward, -h0 is implied.)
-i or --ignore-case
Causes searches to ignore case; that is, uppercase and
lowercase are considered identical. This option is ig‐
nored if any uppercase letters appear in the search pat‐
tern; in other words, if a pattern contains uppercase let‐
ters, then that search does not ignore case.
-I or --IGNORE-CASE
Like -i, but searches ignore case even if the pattern con‐
tains 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 sec‐
ond 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 the line is specified as a
fraction, the actual line number is recalculated if the
terminal window is resized. If any form of the -j option
is used, repeated forward searches (invoked with "n" or
"N") begin at the line immediately after the target line,
and repeated backward searches begin at the target line,
unless changed by -a or -A. For example, if "-j4" is
used, the target line is the fourth line on the screen, so
forward searches begin at the fifth line on the screen.
However nonrepeated searches (invoked with "/" or "?")
always begin at the start or end of the current screen re‐
spectively.
-J or --status-column
Displays a status column at the left edge of the screen.
The character displayed in the status column may be one
of:
> The line is chopped with the -S option, and the
text that is chopped off beyond the right edge of
the screen contains a match for the current search.
< The line is horizontally shifted, and the text that
is shifted beyond the left side of the screen con‐
tains a match for the current search.
= The line is both chopped and shifted, and there are
matches beyond both sides of the screen.
* There are matches in the visible part of the line
but none to the right or left of it.
a-z, A-Z
The line has been marked with the corresponding
letter via the m command.
-kfilename or --lesskey-file=filename
Causes less to open and interpret the named file as a
lesskey(1) binary file. Multiple -k options may be speci‐
fied. If the LESSKEY or LESSKEY_SYSTEM environment vari‐
able is set, or if a lesskey file is found in a standard
place (see KEY BINDINGS), it is also used as a lesskey
file.
--lesskey-src=filename
Causes less to open and interpret the named file as a
lesskey(1) source file. If the LESSKEYIN or
LESSKEYIN_SYSTEM environment variable is set, or if a
lesskey source file is found in a standard place (see KEY
BINDINGS), it is also used as a lesskey source file. Pri‐
or to version 582, the lesskey program needed to be run to
convert a lesskey source file to a lesskey binary file for
less to use. Newer versions of less read the lesskey
source file directly and ignore the binary file if the
source file exists.
-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 do‐
ing 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 subse‐
quently, not to the file which is currently open.
-m or --long-prompt
Causes less to prompt verbosely (like more(1)), 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(1).
-n or --line-numbers
Suppresses line numbers. The default (to use line num‐
bers) may cause less to run more slowly in some cases, es‐
pecially 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 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 exist‐
ing 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. With‐
out 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 speci‐
fying +/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 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 or --quiet or --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 ter‐
minal 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 or --QUIET or --SILENT
Causes totally "quiet" operation: the terminal bell is
never rung. If the terminal has a "visual bell", it is
used in all cases where the terminal bell would have been
rung.
-r or --raw-control-chars
Causes "raw" control characters to be displayed. The de‐
fault is to display control characters using the caret no‐
tation; for example, a control-A (octal 001) is displayed
as "^A" (with some exceptions as described under the -U
option). 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.
USE OF THE -r OPTION IS NOT RECOMMENDED.
-R or --RAW-CONTROL-CHARS
Like -r, but only ANSI "color" escape sequences and OSC 8
hyperlink sequences are output in "raw" form. Unlike -r,
the screen appearance is maintained correctly, provided
that there are no escape sequences in the file other than
these types of escape sequences. Color escape sequences
are only supported when the color is changed within one
line, not across lines. In other words, the beginning of
each line is assumed to be normal (non-colored), regard‐
less of any escape sequences in previous lines. For the
purpose of keeping track of screen appearance, these es‐
cape sequences are assumed to not move the cursor.
OSC 8 hyperlinks are sequences of the form:
ESC ] 8 ; ... \7
The terminating sequence may be either a BEL character
(\7) or the two-character sequence "ESC \".
ANSI color escape sequences are sequences of the form:
ESC [ ... m
where the "..." is zero or more color specification char‐
acters. 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 stan‐
dard 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 sin‐
gle 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
displayed until you press RIGHT-ARROW. The default is to
wrap long lines; that is, display the remainder on the
next line. See also the --wordwrap option.
-ttag or --tag=tag
The -t option, followed immediately by a TAG, will edit
the file containing that tag. For this to work, tag in‐
formation 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 tak‐
en 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 termi‐
nal when they appear in the input.
-U or --UNDERLINE-SPECIAL
Causes backspaces, tabs, carriage returns and "formatting
characters" (as defined by Unicode) 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 underlining capability. Also,
backspaces which appear between two identical characters
are treated specially: the overstruck text is printed us‐
ing the terminal's hardware boldface capability. Other
backspaces are deleted, along with the preceding charac‐
ter. Carriage returns immediately followed by a newline
are deleted. Other carriage returns are handled as speci‐
fied by the -r option. Unicode formatting characters,
such as the Byte Order Mark, are sent to the terminal.
Text which is overstruck or underlined can be searched for
if neither -u nor -U is in effect.
See also the --proc-backspace, --proc-tab, and --proc-re‐
turn options.
-V or --version
Displays the version number of less.
-w or --hilite-unread
Temporarily highlights the first "new" line after a for‐
ward movement of a full page. The first "new" line is the
line immediately following the line previously at the bot‐
tom 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. If the --status-line op‐
tion is in effect, the entire line (the width of the
screen) is highlighted. Otherwise, only the text in the
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 af‐
ter 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 posi‐
tions, 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 deinitial‐
ization strings to the terminal. This is sometimes desir‐
able if the deinitialization string does something unnec‐
essary, 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.
-zn or --window=n or -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 some versions of more(1). 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 auto‐
matically changes to 36 lines.
-"cc or --quotes=cc
Changes the filename quoting character. This may be nec‐
essary 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 char‐
acter. Filenames containing a space should then be sur‐
rounded 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 charac‐
ter. 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 charac‐
ters 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 hori‐
zontally 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. 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 recalculated if the
terminal window is resized.
--exit-follow-on-close
When using the "F" command on a pipe, less will automati‐
cally stop waiting for more data when the input side of
the pipe is closed.
--file-size
If --file-size is specified, less will determine the size
of the file immediately after opening the file. Then the
"=" command will display the number of lines in the file.
Normally this is not done, because it can be slow if the
input file is non-seekable (such as a pipe) and is large.
--follow-name
Normally, if the input file is renamed while an F command
is executing, less will continue to display the contents
of the original file despite its name change. If --fol‐
low-name is specified, during an F command less will peri‐
odically attempt to reopen the file by name. If the re‐
open succeeds and the file is a different file from the
original (which means that a new file has been created
with the same name as the original (now renamed) file),
less will display the contents of that new file.
--header=N[,M]
Sets the number of header lines and columns displayed on
the screen. The value may be of the form "N,M" where N
and M are integers, to set the header lines to N and the
header columns to M, or it may be a single integer "N"
which sets the header lines to N and the header columns to
zero, or it may be ",M" which sets the header columns to M
and the header lines to zero. When N is nonzero, the
first N lines at the top of the screen are replaced with
the first N lines of the file, regardless of what part of
the file are being viewed. When M is nonzero, the charac‐
ters displayed at the beginning of each line are replaced
with the first M characters of the line, even if the rest
of the line is scrolled horizontally. If either N or M is
zero, less stops displaying header lines or columns, re‐
spectively. (Note that it may be necessary to change the
setting of the -j option to ensure that the target line is
not obscured by the header line(s).)
--incsearch
Subsequent search commands will be "incremental"; that is,
less will advance to the next line containing the search
pattern as each character of the pattern is typed in.
--intr=c
Use the character c instead of ^X to interrupt a read when
the "Waiting for data" message is displayed. c must be an
ASCII character; that is, one with a value between 1 and
127 inclusive. A caret followed by a single character can
be used to specify a control character.
--line-num-width=n
Sets the minimum width of the line number field when the
-N option is in effect to n characters. The default is 7.
--modelines=n
Before displaying a file, less will read the first n lines
to try to find a vim-compatible modeline. If n is zero,
less does not try to find modelines. By using a modeline,
the file itself can specify the tab stops that should be
used when viewing it.
A modeline contains, anywhere in the line, a program name
("vi", "vim", "ex", or "less"), followed by a colon, pos‐
sibly followed by the word "set", and finally followed by
zero or more option settings. If the word "set" is used,
option settings are separated by spaces, and end at the
first colon. If the word "set" is not used, option set‐
tings may be separated by either spaces or colons. The
word "set" is required if the program name is "less" but
optional if any of the other three names are used. If any
option setting is of the form "tabstop=n" or "ts=n", then
tab stops are automatically set as if --tabs=n had been
given. See the --tabs description for acceptable values
of n.
--mouse
Enables mouse input: scrolling the mouse wheel down moves
forward in the file, scrolling the mouse wheel up moves
backwards in the file, and clicking the mouse sets the "#"
mark to the line where the mouse is clicked. The number
of lines to scroll when the wheel is moved can be set by
the --wheel-lines option. Mouse input works only on ter‐
minals which support X11 mouse reporting, and on the Win‐
dows version of less.
--MOUSE
Like --mouse, except the direction scrolled on mouse wheel
movement is reversed.
--no-keypad
Disables sending the keypad initialization and deinitial‐
ization strings to the terminal. This is sometimes useful
if the keypad strings make the numeric keypad behave in an
undesirable manner.
--no-histdups
This option changes the behavior so that if a search
string or file name is typed in, and the same string is
already in the history list, the existing copy is removed
from the history list before the new one is added. Thus,
a given string will appear only once in the history list.
Normally, a string may appear multiple times.
--no-number-headers
Header lines (defined via the --header option) are not as‐
signed line numbers. Line number 1 is assigned to the
first line after any header lines.
--no-search-headers
Searches do not include header lines or header columns.
--no-vbell
Disables the terminal's visual bell.
--proc-backspace
If set, backspaces are handled as if neither the -u option
nor the -U option were set. That is, a backspace adjacent
to an underscore causes text to be displayed in underline
mode, and a backspace between identical characters cause
text to be displayed in boldface mode. This option over‐
rides the -u and -U options, so that display of backspaces
can be controlled separate from tabs and carriage returns.
If not set, backspace display is controlled by the -u and
-U options.
--PROC-BACKSPACE
If set, backspaces are handled as if the -U option were
set; that is backspaces are treated as control characters.
--proc-return
If set, carriage returns are handled as if neither the -u
option nor the -U option were set. That is, a carriage
return immediately before a newline is deleted. This op‐
tion overrides the -u and -U options, so that display of
carriage returns can be controlled separate from that of
backspaces and tabs. If not set, carriage return display
is controlled by the -u and -U options.
--PROC-RETURN
If set, carriage returns are handled as if the -U option
were set; that is carriage returns are treated as control
characters.
--proc-tab
If set, tabs are handled as if the -U option were not set.
That is, tabs are expanded to spaces. This option over‐
rides the -U option, so that display of tabs can be con‐
trolled separate from that of backspaces and carriage re‐
turns. If not set, tab display is controlled by the -U
options.
--PROC-TAB
If set, tabs are handled as if the -U option were set;
that is tabs are treated as control characters.
--redraw-on-quit
When quitting, after sending the terminal deinitialization
string, redraws the entire last screen. On terminals
whose terminal deinitialization string causes the terminal
to switch from an alternate screen, this makes the last
screenful of the current file remain visible after less
has quit.
--rscroll=c
This option changes the character used to mark truncated
lines. It may begin with a two-character attribute indi‐
cator like LESSBINFMT does. If there is no attribute in‐
dicator, standout is used. If set to "-", truncated lines
are not marked.
--save-marks
Save marks in the history file, so marks are retained
across different invocations of less.
--search-options=...
Sets default search modifiers. The value is a string of
one or more of the characters E, F, K, N, R or W. Setting
any of these has the same effect as typing that control
character at the beginning of every search pattern. For
example, setting --search-options=W is the same as typing
^W at the beginning of every pattern. The value may also
contain a digit between 1 and 5, which has the same effect
as typing ^S followed by that digit at the beginning of
every search pattern. The value "-" disables all default
search modifiers.
--show-preproc-errors
If a preprocessor produces data, then exits with a non-ze‐
ro exit code, less will display a warning.
--status-col-width=n
Sets the width of the status column when the -J option is
in effect. The default is 2 characters.
--status-line
If a line is marked, the entire line (rather than just the
status column) is highlighted. Also lines highlighted due
to the -w option will have the entire line highlighted.
If --use-color is set, the line is colored rather than
highlighted.
--use-backslash
This option changes the interpretations of options which
follow this one. After the --use-backslash option, any
backslash in an option string is removed and the following
character is taken literally. This allows a dollar sign
to be included in option strings.
--use-color
Enables colored text in various places. The -D option can
be used to change the colors. Colored text works only if
the terminal supports ANSI color escape sequences (as de‐
fined in ECMA-48 SGR; see
https://www.ecma-international.org/publications-and-standards/standards/ecma-48).
--wheel-lines=n
Set the number of lines to scroll when the mouse wheel is
scrolled and the --mouse or --MOUSE option is in effect.
The default is 1 line.
--wordwrap
When the -S option is not in use, wrap each line at a
space or tab if possible, so that a word is not split be‐
tween two lines. The default is to wrap at any character.
-- 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.
When entering a command line at the bottom of the screen (for ex‐
ample, 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 retrieve the
previous command which begins with that text.
DOWNARROW [ ESC-j ]
Retrieve the next command line. If you first enter some
text and then press DOWNARROW, it will retrieve the next
command which begins with that text.
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
thru the other matching filenames. If the completed file‐
name is a directory, a "/" is appended to the filename.
(On MS-DOS systems, a "\" is appended.) The environment
variable LESSSEPARATOR can be used to specify a different
character to append to a directory name.
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 en‐
tered 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.
You may define your own less commands by creating a lesskey
source file. This file specifies a set of command keys and an
action associated with each key. You may also change the line-
editing keys (see LINE EDITING), and set environment variables
used by less. See the lesskey(1) manual page for details about
the file format.
If the environment variable LESSKEYIN is set, less uses that as
the name of the lesskey source file. Otherwise, less looks in a
standard place for the lesskey source file: On Unix systems, less
looks for a lesskey file called "$XDG_CONFIG_HOME/lesskey" or
"$HOME/.config/lesskey" or "$HOME/.lesskey". On MS-DOS and Win‐
dows systems, less looks for a lesskey file called
"$HOME/_lesskey", and if it is not found there, then looks for a
lesskey file called "_lesskey" in any directory specified in the
PATH environment variable. On OS/2 systems, less looks for a
lesskey file called "$HOME/lesskey.ini", and if it is not found,
then looks for a lesskey file called "lesskey.ini" in any direc‐
tory specified in the INIT environment variable, and if it not
found there, then looks for a lesskey file called "lesskey.ini"
in any directory specified in the PATH environment variable.
A system-wide lesskey source 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 environ‐
ment variable LESSKEYIN_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 Unix systems,
the system-wide lesskey file is /usr/local/etc/syslesskey. (How‐
ever, 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 Windows systems, the system-wide lesskey
file is c:\_syslesskey. On OS/2 systems, the system-wide lesskey
file is c:\syslesskey.ini.
Previous versions of less (before v582) used lesskey files with a
binary format, produced by the lesskey program. It is no longer
necessary to use the lesskey program.
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 re‐
placement 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 view‐
ing 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 anoth‐
er program, 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 ar‐
guments, 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 occur‐
rences of the string "%s"; the first is replaced with the origi‐
nal name of the file and the second with the name of the replace‐
ment file, which was output by LESSOPEN.
For example, on many Unix systems, these two scripts will allow
you to keep files in compressed format, but still let less view
them directly:
lessopen.sh:
#! /bin/sh
case "$1" in
*.Z) TEMPFILE=$(mktemp)
uncompress -c $1 >$TEMPFILE 2>/dev/null
if [ -s $TEMPFILE ]; then
echo $TEMPFILE
else
rm -f $TEMPFILE
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 LESSCLOSE="less‐
close.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 stan‐
dard 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 verti‐
cal bar (|) to signify that the input preprocessor is an input
pipe. As with non-pipe input preprocessors, the command string
must contain one occurrence of %s, which is replaced with the
filename of the input file.
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 origi‐
nal file is used. To avoid this, if LESSOPEN starts with two
vertical bars, the exit status of the script determines the be‐
havior when the output is empty. If the output is empty and the
exit status is zero, the empty output is considered to be re‐
placement text. If the output is empty and the exit status is
nonzero, the original file is used. For compatibility with pre‐
vious 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 replace‐
ment file to clean up. In this case, the replacement file name
passed to the LESSCLOSE postprocessor is "-".
For compatibility with previous versions of less, the input pre‐
processor or pipe is not used if less is viewing 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 preprocessor command. If standard input is being viewed, the
input preprocessor is passed a file name consisting of a single
dash. Similarly, if the first two characters of LESSOPEN are
vertical bar and dash (|-) or two vertical bars and a dash (||-),
the input pipe is used on standard input as well as other files.
Again, in this case the dash is not considered to be part of the
input pipe command.
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. Pos‐
sible 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 Ser‐
vices. 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 sup‐
ports 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 charac‐
ter set other than the ones definable by LESSCHARSET. In this
case, the environment variable LESSCHARDEF can be used to define
a character set. It should be set to a string where each charac‐
ter in the string represents one character in the character set.
The character "." is used for a normal character, "c" for con‐
trol, and "b" for binary. A decimal number may be used for repe‐
tition. 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 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 setlo‐
cale interface, less will use setlocale to determine the charac‐
ter 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 underlined, "*s" is standout, and "*n" is nor‐
mal. 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 % followed by x, X,
o, d, etc.). For example, if LESSBINFMT is "*u[%x]", binary
characters are displayed in underlined 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, invalid octets, and stray trailing
octets) are displayed individually using LESSBINFMT so as to fa‐
cilitate diagnostic of how the UTF-8 file is ill-formed.
When the character set is utf-8, in rare cases it may be desir‐
able to override the Unicode definition of the type of certain
characters. For example, characters in a Private Use Area are
normally treated as control characters, but if you are using a
custom font with printable characters in that range, it may be
desirable to tell less to treat such characters as printable.
This can be done by setting the LESSUTFCHARDEF environment vari‐
able to a comma-separated list of character type definitions.
Each character type definition consists of either one hexadecimal
codepoint or a pair of codepoints separated by a dash, followed
by a colon and a type character. Each hexadecimal codepoint may
optionally be preceded by a "U" or "U+". If a pair of codepoints
is given, the type is set for all characters inclusively between
the two values. If there are multiple comma-separated codepoint
values, they must be in ascending numerical order. The type
character may be one of:
p A normal printable character.
w A wide (2-space) printable character.
b A binary (non-printable) character.
c A composing (zero width) character.
For example, setting LESSUTFCHARDEF to
E000-F8FF:p,F0000-FFFFD:p,100000-10FFFD:p
would make all Private Use Area characters be treated as print‐
able.
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 spe‐
cially. The prompt mechanism is rather complicated to provide
flexibility, but the ordinary user need not understand the de‐
tails of constructing personalized prompt strings.
A percent sign followed by a single character is expanded accord‐
ing to what the following character is. (References to the input
file size below refer to the preprocessed size, if an input pre‐
processor is being used.)
%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 "tar‐
get" 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 the in‐
put file.
%E Replaced by the name of the editor (from the VISUAL envi‐
ronment variable, or the EDITOR environment variable if
VISUAL is not defined). See the discussion of the LESSED‐
IT feature below.
%f Replaced by the name of the current input file.
%F Replaced by the last component of the name of the current
input file.
%g Replaced by the shell-escaped name of the current input
file. This is useful when the expanded string will be
used in a shell command, such as in LESSEDIT.
%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.
%T Normally expands to the word "file". However if viewing
files via a tags list using the -t option, it expands to
the word "tag".
%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 cer‐
tain conditions. A question mark followed by a single character
acts like an "IF": depending on the following character, a condi‐
tion is evaluated. If the condition is true, any characters fol‐
lowing 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 ques‐
tion 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 char‐
acters (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.
?s Same as "?B".
?x True if there is a next input file (that is, if the cur‐
rent 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 included literally by escaping it
with a backslash.
?n?f%f .?m(%T %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(%T %i of %m) ..?e(END) ?x- Next\: %x.:
?pB%pB\%:byte %bB?s/%s...%t
?f%f .?n?m(%T %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(%T %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. %g
Note that this expands to the editor name, followed by a + and
the line number, followed by the shell-escaped file name. If
your editor does not accept the "+linenumber" syntax, or has oth‐
er 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 pshell 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)
history file
Less can also be compiled to be permanently in "secure" mode.
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(1) command specifica‐
tion. 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 option 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 environ‐
ment variable is used in its place.
Environment variables may be specified either in the system envi‐
ronment as usual, or in a lesskey(1) file. If environment vari‐
ables 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 prece‐
dence over the number of columns specified by the TERM
variable. (But if you have a windowing system which sup‐
ports 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 directory 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 (de‐
fault "0123456789:;[?!"'#%()*+ ".
LESSBINFMT
Format for displaying non-printable, non-control charac‐
ters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSCLOSE
Command line to invoke the (optional) input-postprocessor.
LESSECHO
Name of the lessecho program (default "lessecho"). The
lessecho program is needed to expand metacharacters, 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 de‐
fault depends on the operating system, but is usually:
Linux and Unix
"$XDG_STATE_HOME/lesshst" or "$HOME/.lo‐
cal/state/lesshst" or "$XDG_DATA_HOME/lesshst" or
"$HOME/.lesshst".
Windows and MS-DOS
"$HOME/_lesshst".
OS/2 "$HOME/lesshst.ini" or "$INIT/lesshst.ini".
LESSHISTSIZE
The maximum number of commands to save in the history
file. The default is 100.
LESSKEYIN
Name of the default lesskey source file.
LESSKEY
Name of the default lesskey binary file. (Not used if
"$LESSKEYIN" exists.)
LESSKEYIN_SYSTEM
Name of the default system-wide lesskey source file.
LESSKEY_SYSTEM
Name of the default system-wide lesskey binary file. (Not
used if "$LESSKEYIN_SYSTEM" exists.)
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 SECURI‐
TY.
LESSSEPARATOR
String to be appended to a directory name in filename com‐
pletion.
LESSUTFBINFMT
Format for displaying non-printable Unicode code points.
LESSUTFCHARDEF
Overrides the type of specified Unicode characters.
LESS_COLUMNS
Sets the number of columns on the screen. Unlike COLUMNS,
takes precedence over the system's idea of the screen
size, so it can be used to make less use less than the
full screen width. If set to a negative number, sets the
number of columns used to this much less than the actual
screen width.
LESS_LINES
Sets the number of lines on the screen. Unlike LINES,
takes precedence over the system's idea of the screen
size, so it can be used to make less use less than the
full screen height. If set to a negative number, sets the
number of lines used to this much less than the actual
screen height. When set, less repaints the entire screen
on every movement command, so scrolling may be slower.
LESS_DATA_DELAY
Duration (in milliseconds) after starting to read data
from the input, after which the "Waiting for data" message
will be displayed. The default is 4000 (4 seconds).
LESS_IS_MORE
Emulate the more(1) command.
LESS_TERMCAP_xx
Where "xx" is any two characters, overrides the definition
of the termcap "xx" capability for the terminal.
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 TIOCG‐
WINSZ or WIOCGETD, the window system's idea of the screen
size takes precedence over the LINES and COLUMNS environ‐
ment variables.)
MORE Options which are passed to less automatically when run‐
ning in more-compatible mode.
PATH User's search path (used to find a lesskey file on MS-DOS
and OS/2 systems).
SHELL The shell used to execute the ! command, as well as to ex‐
pand filenames.
TERM The type of terminal on which less is being run.
VISUAL The name of the editor (used for the v command).
XDG_CONFIG_HOME
Possible location of the lesskey file; see the KEY BIND‐
INGS section.
XDG_DATA_HOME
Possible location of the history file; see the description
of the LESSHISTFILE environment variable.
XDG_STATE_HOME
Possible location of the history file; see the description
of the LESSHISTFILE environment variable.
lesskey(1), lessecho(1)
Copyright (C) 1984-2023 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 WITH‐
OUT ANY WARRANTY; without even the implied warranty of MER‐
CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
Mark Nudelman
Report bugs at https://github.com/gwsw/less/issues.
For more information, see the less homepage at
https://greenwoodsoftware.com/less
This page is part of the less (A file pager) project. Informa‐
tion about the project can be found at
⟨http://www.greenwoodsoftware.com/less/⟩. If you have a bug
report for this manual page, see
⟨http://www.greenwoodsoftware.com/less/faq.html#bugs⟩. This page
was obtained from the tarball less-643.tar.gz fetched from
⟨http://www.greenwoodsoftware.com/less/download.html⟩ on
2024-06-14. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
[email protected]
Version 643: 20 Jul 2023 LESS(1)
Pages that refer to this page: homectl(1), importctl(1), journalctl(1), lessecho(1), lesskey(1), localectl(1), loginctl(1), machinectl(1), man(1), more(1), portablectl(1), quilt(1), systemctl(1), systemd(1), systemd-analyze(1), systemd-inhibit(1), systemd-nspawn(1), systemd-vmspawn(1), timedatectl(1), userdbctl(1), environ(7), debugfs(8), systemd-tmpfiles(8)
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