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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 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 num‐
ber 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 character.
z Like SPACE, but if N is specified, it becomes the new win‐
dow 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 win‐
dow 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. Warn‐
ing: some systems use ^Y as a special job control charac‐
ter.
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 speci‐
fied, it becomes the default for future RIGHTARROW and LEF‐
TARROW 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 speci‐
fied, it becomes the default for future RIGHTARROW and LEF‐
TARROW 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. 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.)
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 posi‐
tioned 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 dis‐
played 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 specify the N-th bracket on the line.
( Like {, but applies to parentheses rather than curly brack‐
ets.
) Like }, but applies to parentheses rather than curly brack‐
ets.
[ 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 col‐
umn 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 pre‐
served 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. 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 cur‐
rently 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 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 previ‐
ous 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 cur‐
rently 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 pat‐
tern. If the previous search was modified by ^E, the
search continues in the next (or previous) file if not sat‐
isfied 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 high‐
lighting back on. Any search command will also turn high‐
lighting 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 "cur‐
rent" 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 file‐
name 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 lit‐
eralization 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 num‐
ber 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 set‐
ting 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 set‐
ting 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 let‐
ter. 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 cur‐
rent file. A pound sign (#) is replaced by the name of the
previously examined file. "!!" repeats the last shell com‐
mand. "!" 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.
| <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 let‐
ter 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 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 "-" command.
Most options may be given in one of two forms: either a dash fol‐
lowed by a single letter, or two dashes followed by a long option
name. A long option name may be abbreviated as long as the abbre‐
viation is unambiguous. For example, --quit-at-eof may be abbre‐
viated --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 ($) is found. For example, you can set two -D options
on MS-DOS like this:
LESS="Dn9.1$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 spe‐
cially, 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 dis‐
played 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 dis‐
played screen from the last line up to and including the
target line. This was the default behavior in less ver‐
sions 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 K
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 K (or the amount of space specified by the -b option) is
used for the pipe. Warning: use of -B can result in erro‐
neous 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.
-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 dis‐
played if the terminal is dumb; that is, lacks some impor‐
tant 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
[MS-DOS only] Sets the color of the text displayed. x is a
single character which selects the type of text whose color
is being set: n=normal, s=standout, d=bold, u=underlined,
k=blink. color is a pair of numbers separated by a period.
The first number selects the foreground color and the sec‐
ond 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. The color may start or end with u to use
underline (with the normal color, if by itself), if the
system supports it (Windows only). x may also be a to tog‐
gle strict ANSI sequence rendering (SGR mode).
-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 some‐
what 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 low‐
ercase 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 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 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 the line is specified as a fraction, the actual
line number is recalculated if the terminal window is
resized, so that the target line remains at the specified
fraction of the screen height. 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
respectively.
-J or --status-column
Displays a status column at the left edge of the screen.
The status column shows the lines that matched the current
search, and any lines that are marked (via the m or M com‐
mand). The status column is also used if the -w or -W
option is in effect.
-kfilename or --lesskey-file=filename
Causes less to open and interpret the named file as a
lesskey (1) file. Multiple -k options may be specified.
If the LESSKEY or LESSKEY_SYSTEM environment variable is
set, or if a lesskey file is found in a standard place (see
KEY BINDINGS), it is also used as a lesskey file.
-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 subse‐
quently, not to the file which is currently open.
-m or --long-prompt
Causes less to prompt verbosely (like more), with the per‐
cent 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
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 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. 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 specify‐
ing +/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
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 main‐
tained correctly in most cases. ANSI "color" escape
sequences are sequences of the form:
ESC [ ... m
where the "..." is zero or more color specification charac‐
ters 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 char‐
acters 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 char‐
acters 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 informa‐
tion 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 envi‐
ronment 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 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 spe‐
cially: the underlined text is displayed using the termi‐
nal's hardware underlining capability. Also, backspaces
which appear between two identical characters are treated
specially: the overstruck text is printed using the termi‐
nal's hardware boldface capability. Other backspaces are
deleted, along with the preceding character. Carriage
returns immediately followed by a newline are deleted.
Other carriage returns are handled as specified by the -r
option. Text which is overstruck or underlined can be
searched for if neither -u nor -U is in effect.
-V or --version
Displays the version number of less.
-w or --hilite-unread
Temporarily highlights the first "new" line after a forward
movement of a full page. The first "new" line is the line
immediately following the line previously at the bottom of
the screen. Also highlights the target line after a g or p
command. The highlight is removed at the next command
which causes movement. The entire line is highlighted,
unless the -J option is in effect, in which case only the
status column is highlighted.
-W 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 deinitial‐
ization strings to the terminal. This is sometimes desir‐
able if the deinitialization string does something unneces‐
sary, 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. 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 neces‐
sary if you are trying to name a file which contains both
spaces and quote characters. Followed by a single charac‐
ter, 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. File‐
names containing a space should then be preceded by the
open quote character and followed by the close quote char‐
acter. Note that even after the quote characters are
changed, this option remains -" (a dash followed by a dou‐
ble 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, 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 the contents of
the original file despite its name change. If --follow-
name is specified, during an F command less will periodi‐
cally attempt to reopen the file by name. If the reopen
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.
--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 terminals
which support X11 mouse reporting, and on the Windows ver‐
sion 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. Nor‐
mally, a string may appear multiple times.
--rscroll
This option changes the character used to mark truncated
lines. It may begin with a two-character attribute indica‐
tor like LESSBINFMT does. If there is no attribute indica‐
tor, 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.
--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.
--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.
-- 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 exam‐
ple, 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 Win‐
dows 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 pre‐
vious 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
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 com‐
mand 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 speci‐
fied 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 man‐
ual page for more details.
A system-wide lesskey file may also be set up to provide key bind‐
ings. If a key is defined in both a local lesskey file and in the
system-wide file, key bindings in the local file take precedence
over those in the system-wide file. If the environment variable
LESSKEY_SYSTEM is set, less uses that as the name of the system-
wide lesskey file. Otherwise, less looks in a standard place for
the system-wide lesskey file: On 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 preprocessor a chance to
modify the way the contents of the file are displayed. An input
preprocessor is simply an executable program (or shell script),
which writes the contents of the file to a different file, called
the replacement file. The contents of the replacement file are
then displayed in place of the contents of the original file.
However, it will appear to the user as if the original file is
opened; that is, less will display the original filename as the
name of the current file.
An input preprocessor receives one command line argument, the
original filename, as entered by the user. It should create the
replacement file, and when finished, print the name of the
replacement file to its standard output. If the input preproces‐
sor 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 file‐
name 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, which may perform any
desired clean-up action (such as deleting the replacement file
created by LESSOPEN). This program receives two command line
arguments, the original filename as entered by the user, and the
name of the replacement file. To set up an input postprocessor,
set the LESSCLOSE environment variable to a command line which
will invoke your input postprocessor. It may include two occur‐
rences of the string "%s"; the first is replaced with the original
name of the file and the second with the name of the replacement
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="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 writ‐
ing the name of a replacement file on its standard output, writes
the entire contents of the replacement file on its standard out‐
put. If the input pipe does not write any characters on its stan‐
dard 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. 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 ver‐
tical bars, the exit status of the script becomes meaningful. If
the exit status is zero, the output is considered to be replace‐
ment text, even if it is empty. If the exit status is nonzero,
any output is ignored and the original file is used. For compati‐
bility 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 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 ver‐
tical 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 used following files to set up default preprocessor:
/etc/profile.d/less.sh
/etc/profile.d/less.csh
These files set up /usr/bin/lesspipe.sh as a default filter. An
user defined filter can be specified in ~/.lessfilter. This file
should have an execute bit set and accept only one parameter,
which represents a filename. If the user defined filter process
the file, zero should be returned. Otherwise ~/.lessfilter tries
to handle the file.
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. 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 character
set other than the ones definable by LESSCHARSET. In this case,
the environment variable LESSCHARDEF can be used to define a char‐
acter 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 char‐
acters 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 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 underlined, "*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 % followed by x, X, o,
d, etc.). For example, if LESSBINFMT is "*u[%x]", binary charac‐
ters are displayed in underlined hexadecimal surrounded by brack‐
ets. 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 spe‐
cially. The prompt mechanism is rather complicated to provide
flexibility, but the ordinary user need not understand the details
of constructing personalized prompt strings.
A percent sign followed by a single character is expanded accord‐
ing 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 "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 input
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 LESSEDIT
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 char‐
acters are not included. A colon appearing between the question
mark and the period can be used to establish an "ELSE": any char‐
acters 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.
?s Same as "?B".
?x True if there is a next input file (that is, if the current
input file is not the last one).
Any characters other than the special ones (question mark, colon,
period, percent, and backslash) become literally part of the
prompt. Any of the special characters may be included in the
prompt literally by preceding it with a backslash.
Some examples:
?f%f:Standard input.
This prompt prints the filename, if known; otherwise the string
"Standard input".
?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...
This prompt would print the filename, if known. The filename is
followed by the line number, if known, otherwise the percent if
known, otherwise the byte offset if known. Otherwise, a dash is
printed. Notice how each question mark has a matching period, and
how the % after the %pt is 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 other dif‐
ferences 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
-k use of lesskey files
-t use of tags files
metacharacters in filenames, such as *
filename completion (TAB, ^L)
Less can also be compiled to be permanently in "secure" mode.
COMPATIBILITY WITH MORE
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 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 environment
variable is used in its place.
ENVIRONMENT VARIABLES
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 precedence
over the number of columns 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.)
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 (default
"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 dis‐
cussion 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 com‐
pletion.
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 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 running
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
expand filenames.
TERM The type of terminal on which less is being run.
VISUAL The name of the editor (used for the v command).
SEE ALSO
lesskey(1)
COPYRIGHT
Copyright (C) 1984-2019 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 Foun‐
dation; 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.
AUTHOR
Mark Nudelman
Report bugs at https://github.com/gwsw/less/issues.
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.
Version 551: 11 Jun 2019 LESS(1)