less
opposite of more
see also :
lesskey
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.)
add an example, a script, a trick and tips
examples
source
How to turn off word-wrap in less
Don't know if less has a option for that, but I use the most command which does that by default (and
allows scrolling left/right to view it)
source
How can I have `less` automatically decompress `xz` files like it did with `gz` files on my old SUSE distro?
The functionality is provided by lesspipe. Install it and put (I don't have a SUSE
machine at the moment to check)
[ -x /usr/bin/lessopen.sh ] && eval /usr/bin/lessopen.sh
in your shell configuration (e.g., .bashrc
)
source
Get colors in 'less'' command
Try the following:
less -R
from man less
:
-r or --raw-control-chars
Causes "raw" control characters to be displayed. (...)
-R or --RAW-CONTROL-CHARS
Like -r, but only ANSI "color" escape sequences are output in
"raw" form. (...)
source
less is more? Is more less? I'm so confused
more
is a basic pager, which allows you to scroll
downwards, one page at a time. Only downwards.
less
is also a pager, but has addition functionality
to scroll upwards and downwards through the input, in addition to
several other extensions.
So, yes. less
is more, and more
is
less. Another common idiom (according to the wiki entry) is
"less
is more
, more or less." The name
comes from the fact that the author (Mark Nudelman) essentially
wanted a program that was "backwards more" -- The opposite of
more, is less
.
source
Getting LESS to return back to command line if a short file is displayed
See manpage:
-F or --quit-if-one-screen
Causes less to automatically exit if the entire file can be
displayed on the first screen.
source
Why does less tail mode stop working?
maybe you could try tail -f [filename]
instead?
source
How do I execute a Linux command whilst using the less command or within the man pages?
You can access the command line using bang (!
)
within less.
So for example, if you type:
touch temp.txt
ls | less
!rm temp.txt
And temp.txt should be gone.
Edit: By default it seems that man now uses less
to page (for some reason I thought it used more
,
maybe in the past it did). You can use the same trick, but it
requires the full path (eg. /home/user/...) to get it to work.
This is because invoking man changes the current working
directory. On my machine (xubuntu, using
xfce-terminal
) it goes to
/usr/share/man
. If your console displays the CWD you
can see it change, or you can see it from within man
by entering:
!pwd
source
How do you search for tabs in the linux command less?
Press / then CtrlV, followed by
Tab.
source
Incremental searching with the `less` utility
Unfortunately the less
pager does not have this
functionality. The only search options available are
/
for a forward search, and ?
for a
backward search.
source
Less hotkeys not working, printing keycodes instead performing action
php -i
is doing something weird with stdin. Try
this:
php -i </dev/null | less
source
How to turn off word-wrap in less
Don't know if less has a option for that, but I use the most command
which does that by default (and allows scrolling left/right to
view it)
source
How do you run `less` and have it run a search pattern automatically?
You mean like?
less -p PATTERN filename
That is in the manual.
source
Why less -F option does not work with -S option
Works for me; less -FS
exits immediately if the
input can be printed on one screen without folding lines, and
acts normally if scrolling (either to the right or down) is
needed.
source
Unix command to empty logfile from within "less"?
The easiest I can think of is probably to use ^Z
to
put the current process in the background, remove your files, and
type fg
to go back to your process. That said,
removing log files is not the best way to deal with them, it's
much better usually to use logrotate
to compress
them.
description
Less is
a program similar to more (1), but it has many more
features. 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.
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 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 ($) is found. For example, you can
set two -D options on MS-DOS like this:
LESS="Dn9.1$Ds4.1"
A dollar sign
or backslash may be included literally in an option string
by preceding it with a backslash.
-? 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 64K of buffer space is
used for each file (unless the file is a pipe; see the
-B option). The -b option specifies instead that
n kilobytes of buffer space should be used for each
file. If n is -1, buffer space is unlimited;
that is, the entire file can be read into memory.
-B or
--auto-buffers
By default, when data is read
from a pipe, buffers are allocated automatically as needed.
If a large amount of data is read from the pipe, this can
cause a large amount of memory to be allocated. The -B
option disables this automatic allocation of buffers for
pipes, so that only 64K (or the amount of space specified by
the -b option) is used for the pipe. Warning: use of
-B can result in erroneous display, since only the
most recently viewed part of the piped data is kept in
memory; any earlier data is lost.
-c or
--clear-screen
Causes full screen repaints to
be painted from the top line down. By default, full screen
repaints are done by scrolling from the bottom of the
screen.
-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
[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 second selects the
background color of the text. A single number N is
the same as N.M, where M is the normal
background color.
-e or
--quit-at-eof
Causes less to
automatically exit the second time it reaches end-of-file.
By default, the only way to exit less is via the
"q" command.
-E or
--QUIT-AT-EOF
Causes less to
automatically exit the first time it reaches
end-of-file.
-f or
--force
Forces non-regular files to be
opened. (A non-regular file is a directory or a device
special file.) Also suppresses the warning message when a
binary file is opened. By default, less will refuse
to open non-regular files. Note that some operating systems
will not allow directories to be read, even if -f is
set.
-F or
--quit-if-one-screen
Causes less to
automatically exit if the entire file can be displayed on
the first screen.
-g or
--hilite-search
Normally, less will
highlight ALL strings which match the last search command.
The -g option changes this behavior to highlight only
the particular string which was found by the last search
command. This can cause less to run somewhat faster
than the default.
-G or
--HILITE-SEARCH
The -G option suppresses
all highlighting of strings found by search commands.
-hn or
--max-back-scroll=n
Specifies a maximum number of
lines to scroll backward. If it is necessary to scroll
backward more than n lines, the screen is repainted
in a forward direction instead. (If the terminal does not
have the ability to scroll backward, -h0 is
implied.)
-i or
--ignore-case
Causes searches to ignore case;
that is, uppercase and lowercase are considered identical.
This option is ignored if any uppercase letters appear in
the search pattern; in other words, if a pattern contains
uppercase letters, then that search does not ignore
case.
-I or
--IGNORE-CASE
Like -i, but searches
ignore case even if the pattern contains uppercase
letters.
-jn or
--jump-target=n
Specifies a line on the screen
where the "target" line is to be positioned. The
target line is the line specified by any command to search
for a pattern, jump to a line number, jump to a file
percentage or jump to a tag. The screen line may be
specified by a number: the top line on the screen is 1, the
next is 2, and so on. The number may be negative to specify
a line relative to the bottom of the screen: the bottom line
on the screen is -1, the second to the bottom is
-2, and so on. Alternately, the screen line may be
specified as a fraction of the height of the screen,
starting with a decimal point: .5 is in the middle of the
screen, .3 is three tenths down from the first line, and so
on. If 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, forward searches begin at the line immediately after
the target line, and 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.
-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. 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 subsequently, not to the file which is
currently open.
-m or
--long-prompt
Causes less to prompt
verbosely (like more), with the percent into the
file. By default, less prompts with a colon.
-M or
--LONG-PROMPT
Causes less to prompt
even more verbosely than more.
-n or
--line-numbers
Suppresses line numbers. The
default (to use line numbers) may cause less to run
more slowly in some cases, especially with a very large
input file. Suppressing line numbers with the -n
option will avoid this problem. Using line numbers means:
the line number will be displayed in the verbose prompt and
in the = command, and the v command will pass the current
line number to the editor (see also the 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. Without
a file name, they will simply report the name of the log
file. The "s" command is equivalent to specifying
-o from within less.
-ppattern or
--pattern=pattern
The -p option on the
command line is equivalent to specifying +/pattern;
that is, it tells less to start at the first
occurrence of pattern in the file.
-Pprompt or
--prompt=prompt
Provides a way to tailor the
three prompt styles to your own preference. This option
would normally be put in the LESS environment variable,
rather than being typed in with each less command.
Such an option must either be the last option in the LESS
variable, or be terminated by a dollar sign. -Ps followed by
a string changes the default (short) prompt to that string.
-Pm changes the medium (-m) prompt. -PM changes the
long (-M) prompt. -Ph changes the prompt for the help
screen. -P= changes 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 terminal has a
"visual bell", it is used instead. The bell will
be rung on certain other errors, such as typing an invalid
character. The default is to ring the terminal bell in all
such cases.
-Q or --QUIET
or --SILENT
Causes totally
"quiet" operation: the terminal bell is never
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 maintained correctly in most cases. ANSI
"color" escape sequences are sequences of the
form:
ESC [ ... m
where the
"..." is zero or more color specification
characters For the purpose of keeping track of screen
appearance, ANSI color escape sequences are assumed to not
move the cursor. You can make less think that
characters other than "m" can end ANSI color
escape sequences by setting the environment variable
LESSANSIENDCHARS to the list of characters which can end a
color escape sequence. And you can make less think
that characters other than the standard ones may appear
between the ESC and the m by setting the environment
variable LESSANSIMIDCHARS to the list of characters which
can appear.
-s or
--squeeze-blank-lines
Causes consecutive blank lines
to be squeezed into a single blank line. This is useful when
viewing nroff output.
-S or
--chop-long-lines
Causes lines longer than the
screen width to be chopped (truncated) rather than wrapped.
That is, the portion of a long line that does not fit in the
screen width is not shown. The default is to wrap long
lines; that is, display the remainder on the next line.
-ttag or
--tag=tag
The -t option, followed
immediately by a TAG, will edit the file containing that
tag. For this to work, tag information must be available;
for example, there may be a file in the current directory
called "tags", which was previously built by
ctags (1) or an equivalent command. If the
environment variable LESSGLOBALTAGS is set, it is taken to
be the name of a command compatible with global (1),
and that command is executed to find the tag. (See
http://www.gnu.org/software/global/global.html). The
-t option may also be specified from within
less (using the - command) as a way of
examining a new file. The command ":t" is
equivalent to specifying -t from within
less.
-Ttagsfile or
--tag-file=tagsfile
Specifies a tags file to be
used instead of "tags".
-u or
--underline-special
Causes backspaces and carriage
returns to be treated as printable characters; that is, they
are sent to the terminal when they appear in the input.
-U or
--UNDERLINE-SPECIAL
Causes backspaces, tabs and
carriage returns to be treated as control characters; that
is, they are handled as specified by the -r
option.
By default, if
neither -u nor -U is given, backspaces which
appear adjacent to an underscore character are treated
specially: the underlined text is displayed using the
terminal’s hardware underlining capability. Also,
backspaces which appear between two identical characters are
treated specially: the overstruck text is printed using the
terminal’s hardware boldface capability. Other
backspaces are deleted, along with the preceding character.
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 deinitialization strings to the terminal.
This is sometimes desirable if the deinitialization string
does something unnecessary, like clearing the screen.
-yn or
--max-forw-scroll=n
Specifies a maximum number of
lines to scroll forward. If it is necessary to scroll
forward more than n lines, the screen is repainted
instead. The -c or -C option may be used to
repaint from the top of the screen if desired. By default,
any forward movement causes scrolling.
-[z]n or
--window=n
Changes the default scrolling
window size to n lines. The default is one screenful.
The z and w 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 necessary if you are trying to name a
file which contains both spaces and quote characters.
Followed by a single character, this changes the quote
character to that character. Filenames containing a space
should then be surrounded by that character rather than by
double quotes. Followed by two characters, changes the open
quote to the first character, and the close quote to the
second character. Filenames containing a space should then
be preceded by the open quote character and followed by the
close quote character. Note that even after the quote
characters are changed, this option remains -" (a
dash followed by a double quote).
-~ or
--tilde
Normally lines after end of
file are displayed as a single tilde (~). This option causes
lines after end of file to be displayed as blank lines.
-# or
--shift
Specifies the default number of
positions to scroll horizontally in the RIGHTARROW and
LEFTARROW 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.
--no-keypad
Disables sending the keypad
initialization and deinitialization strings to the terminal.
This is sometimes useful if the keypad strings make the
numeric keypad behave in an undesirable manner.
--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 periodically
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.
--
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.
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 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.
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.
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.)
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 top line, a number N may be used to specify the N-th
bracket on the line.
(
Like {, but applies to parentheses rather than curly brackets.
)
Like }, but applies to parentheses rather than curly brackets.
[
Like {, but applies to square brackets rather than curly
brackets.
]
Like }, but applies to square brackets rather than curly
brackets.
ESC-^F
Followed by two characters, acts like {, but uses the two
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 letter, marks the current position with
that letter.
’
(Single quote.) Followed by any lowercase letter, returns to the
position which was previously marked with that letter. Followed
by another single quote, returns to the position at which the
last "large" movement command was executed. Followed by a ^ or $,
jumps to the beginning or end of the file respectively. Marks are
preserved when a new file is examined, so the ’ command can be
used to switch between input files.
^X^X
Same as single quote.
/pattern
Search forward in the file for the N-th line containing the
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 currently displayed on
the screen or the settings of the -a or -j options.
^K
Highlight any text which matches the pattern on the current
screen, but don’t move to the first match (KEEP current
position).
^R
Don’t interpret regular expression metacharacters; that is, do a
simple textual comparison.
?pattern
Search backward in the file for the N-th line containing the
pattern. The search starts at the line immediately before the top
line displayed.
Certain characters are special as in the / command:
^N or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search reaches the
beginning of the current file without finding a match, the search
continues in the previous file in the command line list.
^F or @
Begin the search at the last line of the last file in the command
line list, regardless of what is currently displayed on the
screen or the settings of the -a or -j options.
^K
As in forward searches.
^R
As in forward searches.
ESC-/pattern
Same as "/*".
ESC-?pattern
Same as "?*".
n
Repeat previous search, for N-th line containing the last
pattern. If the previous search was modified by ^N, the search is
made for the N-th line NOT containing the pattern. If the
previous search was 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.)
&pattern
Display only lines which match the pattern; lines which do not
match the pattern are not displayed. If pattern is empty (if you
type & immediately followed by ENTER), any filtering is turned
off, and all lines are displayed. While filtering is in effect,
an ampersand is displayed at the beginning of the prompt, as a
reminder that some lines in the file may be hidden.
Certain characters are special as in the / command:
^N or !
Display only lines which do NOT match the pattern.
^R
Don’t interpret regular expression metacharacters; that is, do a
simple textual comparison.
:e [filename]
Examine a new file. If the filename is missing, the "current"
file (see the :n and :p commands below) from the list of files in
the command line is re-examined. A percent sign (%) in the
filename is replaced by the name of the current file. A pound
sign (#) is replaced by the name of the previously examined file.
However, two consecutive percent signs are simply replaced with a
single percent sign. This allows you to enter a filename that
contains a percent sign in the name. Similarly, two 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 four commands may or may not be valid, depending on
your particular installation.
v
Invokes an editor to edit the current file being viewed. The
editor is taken from the environment variable VISUAL if defined,
or EDITOR if VISUAL is not defined, or defaults to "vi" if
neither VISUAL nor EDITOR is defined. See also the discussion of
LESSEDIT under the section on PROMPTS below.
! shell-command
Invokes a shell to run the shell-command given. A percent sign
(%) in the command is replaced by the name of the current file. A
pound sign (#) is replaced by the name of the previously examined
file. "!!" repeats the last shell command. "!" with no shell
command simply invokes a shell. On Unix 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 first line on the current screen and the
position marked by the letter. <m> may also be ^ or $ to
indicate beginning or end of file respectively. If <m> is .
or newline, the current screen is piped.
s filename
Save the input to a file. This only works if the input is a pipe,
not an ordinary file.
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
specification. In this mode, less behaves differently in these
ways:
The -e option works differently. If the -e option is not set,
less behaves as if the -E option were set. If the -e
option is set, less behaves as if the -e and -F options
were set.
The -m option works differently. If the -m option is not set, the
medium prompt is used, and it is prefixed with the string
"--More--". If the -m option is set, the short prompt is used.
The -n option acts like the -z option. The normal behavior of the
-n option is unavailable in this mode.
The parameter to the -p option is taken to be a less
command rather than a search pattern.
The LESS environment variable is ignored, and the MORE
environment variable is used in its place.
copyright
Copyright (C) 1984-2012 Mark Nudelman
less is part of the GNU project and is free software. You can
redistribute it and/or modify it under the terms of either (1)
the GNU General Public License as published by the Free Software
Foundation; or (2) the Less License. See the file README in the
less distribution for more details regarding redistribution. You
should have received a copy of the GNU General Public License
along with the source for less; see the file COPYING. If not,
write to the Free Software Foundation, 59 Temple Place, Suite
330, Boston, MA 02111-1307, USA. You should also have received a
copy of the Less License; see the file LICENSE.
less is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
environment variables
Environment variables may be specified either in the system
environment as usual, or in a lesskey (1) file. If
environment variables are defined in more than one place,
variables defined in a local lesskey file take precedence over
variables defined in the system environment, which take
precedence over variables defined in the system-wide lesskey
file.
COLUMNS
Sets the number of columns on the screen. Takes precedence over
the number of columns specified by the TERM variable. (But if you
have a windowing system which supports TIOCGWINSZ or WIOCGETD,
the window system’s idea of the screen size takes precedence over
the LINES and COLUMNS environment variables.)
EDITOR
The name of the editor (used for the v command).
HOME
Name of the user’s home directory (used to find a lesskey file on
Unix and OS/2 systems).
HOMEDRIVE, HOMEPATH
Concatenation of the HOMEDRIVE and HOMEPATH environment variables
is the name of the user’s home 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 characters.
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 default is
"$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" on
OS/2 systems.
LESSHISTSIZE
The maximum number of commands to save in the history file. The
default is 100.
LESSKEY
Name of the default lesskey(1) file.
LESSKEY_SYSTEM
Name of the default system-wide lesskey(1) file.
LESSMETACHARS
List of characters which are considered "metacharacters" by the
shell.
LESSMETAESCAPE
Prefix which less will add before each metacharacter in a command
sent to the shell. If LESSMETAESCAPE is an empty string, commands
containing metacharacters will not be passed to the shell.
LESSOPEN
Command line to invoke the (optional) input-preprocessor.
LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.
LESSSEPARATOR
String to be appended to a directory name in filename completion.
LESSUTFBINFMT
Format for displaying non-printable Unicode code points.
LESS_IS_MORE
Emulate the more (1) command.
LINES
Sets the number of lines on the screen. Takes precedence over the
number of lines specified by the TERM variable. (But if you have
a windowing system which supports TIOCGWINSZ or WIOCGETD, the
window system’s idea of the screen size takes precedence over the
LINES and COLUMNS environment variables.)
MORE
Options which are passed to less automatically when
running in more compatible mode.
PATH
User’s search path (used to find a lesskey file on MS-DOS and
OS/2 systems).
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).
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
preprocessor does not output a replacement filename, less
uses the original file, as normal. The input preprocessor is not
called when viewing standard input. To set up an input
preprocessor, set the LESSOPEN environment variable to a command
line which will invoke your input preprocessor. This command line
should include one occurrence of the string "%s", which will be
replaced by the filename when the input preprocessor command is
invoked.
When less closes a file opened in such a way, it will call
another 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 occurrences 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) uncompress -
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac
lessclose.sh:
#! /bin/sh
rm $2
To use these scripts, put them both where they can be executed
and set LESSOPEN="lessopen.sh %s", and
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 writing the name of a replacement file on its standard
output, writes the entire contents of the replacement file on its
standard output. If the input pipe does not write any characters
on its standard output, then there is no replacement file and
less uses the original file, as normal. To use an input
pipe, make the first character in the LESSOPEN environment
variable a vertical bar (|) to signify that the input
preprocessor is an input pipe.
For example, on many Unix systems, this script will work like the
previous example scripts:
lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
*) exit 1
;;
esac
exit $?
To use this script, put it where it can be executed and set
LESSOPEN="|lesspipe.sh %s".
Note that a preprocessor cannot output an empty file, since that
is interpreted as meaning there is no replacement, and the
original file is used. To avoid this, if LESSOPEN starts with two
vertical bars, the exit status of the script becomes meaningful.
If the exit status is zero, the output is considered to be
replacement text, even if it empty. If the exit status is
nonzero, any output is ignored and the original file is used. For
compatibility with previous versions of less, if LESSOPEN
starts with only one vertical bar, the exit status of the
preprocessor is ignored.
When an input pipe is used, a LESSCLOSE postprocessor can be
used, but it is usually not necessary since there is no
replacement file to clean up. In this case, the replacement file
name passed to the LESSCLOSE postprocessor is "-".
For compatibility with previous versions of less, the
input preprocessor 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.
key bindings
You may define your own less commands by using the program
lesskey (1) to create a lesskey file. This file specifies
a set of command keys and an action associated with each key. You
may also use lesskey to change the line-editing keys (see
LINE EDITING), and to set environment variables. If the
environment variable LESSKEY is set, less uses that as the
name of the lesskey file. Otherwise, less looks in a
standard place for the lesskey file: On Unix systems, less
looks for a lesskey file called "$HOME/.less". On MS-DOS and
Windows systems, less looks for a lesskey file called
"$HOME/_less", and if it is not found there, then looks for a
lesskey file called "_less" in any directory specified in the
PATH environment variable. On OS/2 systems, less looks for
a lesskey file called "$HOME/less.ini", and if it is not found,
then looks for a lesskey file called "less.ini" in any directory
specified in the INIT environment variable, and if it not found
there, then looks for a lesskey file called "less.ini" in any
directory specified in the PATH environment variable. See the
lesskey manual page for more details.
A system-wide lesskey file may also be set up to provide key
bindings. If a key is defined in both a local lesskey file and in
the system-wide file, key bindings in the local file take
precedence over those in the system-wide file. If the environment
variable LESSKEY_SYSTEM is set, less uses that as the name
of the 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 Windows systems, the
system-wide lesskey file is c:\_sysless. On OS/2 systems, the
system-wide lesskey file is c:\sysless.ini.
line editing
When entering command line at the bottom of the screen (for
example, a filename for the :e command, or the pattern for a
search command), certain keys can be used to manipulate the
command line. Most commands have an alternate form in [ brackets
] which can be used if a key does not exist on a particular
keyboard. (Note that the forms beginning with ESC do not work in
some MS-DOS and Windows systems because ESC is the line erase
character.) Any of these special keys may be entered literally by
preceding it with the "literal" character, either ^V or ^A. A
backslash itself may also be entered literally by entering two
backslashes.
LEFTARROW [ ESC-h ]
Move the cursor one space to the left.
RIGHTARROW [ ESC-l ]
Move the cursor one space to the right.
^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
(That is, CONTROL and LEFTARROW simultaneously.) Move the cursor
one word to the left.
^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
(That is, CONTROL and RIGHTARROW simultaneously.) Move the cursor
one word to the right.
HOME [ ESC-0 ]
Move the cursor to the beginning of the line.
END [ ESC-$ ]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or cancel the
command if the command line is empty.
DELETE or [ ESC-x ]
Delete the character under the cursor.
^BACKSPACE [ ESC-BACKSPACE ]
(That is, CONTROL and BACKSPACE simultaneously.) Delete the word
to the left of the cursor.
^DELETE [ ESC-X or ESC-DELETE ]
(That is, CONTROL and DELETE simultaneously.) Delete the word
under the cursor.
UPARROW [ ESC-k ]
Retrieve the previous command line. If you first enter some text
and then press UPARROW, it will 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 filename 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.
national character sets
There are three types of characters in the input file:
normal characters
can be displayed directly to the screen.
control characters
should not be displayed directly, but are expected to be found in
ordinary text files (such as backspace and tab).
binary characters
should not be displayed directly and are not expected to be found
in text files.
A "character set" is simply a description of which characters are
to be considered normal, control, and binary. The LESSCHARSET
environment variable may be used to select a character set.
Possible values for LESSCHARSET are:
ascii
BS, TAB, NL, CR, and formfeed are control characters, all chars
with values between 32 and 126 are normal, and all others are
binary.
iso8859
Selects an ISO 8859 character set. This is the same as ASCII,
except characters between 160 and 255 are treated as normal
characters.
latin1
Same as iso8859.
latin9
Same as iso8859.
dos
Selects a character set appropriate for MS-DOS.
ebcdic
Selects an EBCDIC character set.
IBM-1047
Selects an EBCDIC character set used by OS/390 Unix Services.
This is the EBCDIC analogue of latin1. You get similar results by
setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
environment.
koi8-r
Selects a Russian character set.
next
Selects a character set appropriate for NeXT computers.
utf-8
Selects the UTF-8 encoding of the ISO 10646 character set. UTF-8
is special in that it supports multi-byte characters in the input
file. It is the only character set that supports multi-byte
characters.
windows
Selects a character set appropriate for Microsoft Windows (cp
1251).
In rare cases, it may be desired to tailor less to use a
character set other than the ones definable by 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
character in the string represents one character in the character
set. The character "." is used for a normal character, "c" for
control, and "b" for binary. A decimal number may be used for
repetition. For example, "bccc4b." would mean character 0 is
binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8
is normal. All characters after the last are taken to be the same
as the last, so 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
setlocale interface, less will use setlocale to
determine the character set. setlocale is controlled by setting
the LANG or LC_CTYPE environment variables.
Finally, if the setlocale interface is also not available,
the default character set is latin1.
Control and binary characters are displayed in standout (reverse
video). Each such character is displayed in caret notation if
possible (e.g. ^A for control-A). Caret notation is used only if
inverting the 0100 bit results in a normal printable character.
Otherwise, the character is displayed as a hex number in angle
brackets. This format can be changed by setting the LESSBINFMT
environment variable. LESSBINFMT may begin with a "*" and one
character to select the display attribute: "*k" is blinking, "*d"
is bold, "*u" is 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
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, illegal octets, and stray
trailing octets) are displayed individually using LESSBINFMT so
as to facilitate diagnostic of how the UTF-8 file is ill-formed.
prompts
The -P option allows you to tailor the prompt to your preference.
The string given to the -P option replaces the specified prompt
string. Certain characters in the string are interpreted
specially. The prompt mechanism is rather complicated to provide
flexibility, but the ordinary user need not understand the
details of constructing personalized prompt strings.
A percent sign followed by a single character is expanded
according to what the following character is:
%bX
Replaced by the byte offset into the current input file. The b is
followed by a single character (shown as X above) which
specifies the line whose byte offset is to be used. If the
character is a "t", the byte offset of the top line in the
display is used, an "m" means use the middle line, a "b" means
use the bottom line, a "B" means use the line just after the
bottom line, and a "j" means use the "target" line, as specified
by the -j option.
%B
Replaced by the size of the current input file.
%c
Replaced by the column number of the text appearing in the first
column of the screen.
%dX
Replaced by the page number of a line in the input file. The line
to be used is determined by the X, as with the %b option.
%D
Replaced by the number of pages in the input file, or
equivalently, the page number of the last line in the input file.
%E
Replaced by the name of the editor (from the VISUAL environment
variable, or the EDITOR environment variable if VISUAL is not
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.
%i
Replaced by the index of the current file in the list of input
files.
%lX
Replaced by the line number of a line in the input file. The line
to be used is determined by the X, as with the %b option.
%L
Replaced by the line number of the last line in the input file.
%m
Replaced by the total number of input files.
%pX
Replaced by the percent into the current input file, based on
byte offsets. The line used is determined by the X as with
the %b option.
%PX
Replaced by the percent into the current input file, based on
line numbers. The line used is determined by the X as with
the %b option.
%s
Same as %B.
%t
Causes any trailing spaces to be removed. Usually used at the end
of the string, but may appear anywhere.
%x
Replaced by the name of the next input file in the list.
If any item is unknown (for example, the file size if input is a
pipe), a question mark is printed instead.
The format of the prompt string can be changed depending on
certain conditions. A question mark followed by a single
character acts like an "IF": depending on the following
character, a condition is evaluated. If the condition is true,
any characters following the question mark and condition
character, up to a period, are included in the prompt. If the
condition is false, such characters are not included. A colon
appearing between the question mark and the period can be used to
establish an "ELSE": any characters between the colon and the
period are included in the string if and only if the IF condition
is false. Condition characters (which follow a question mark) may
be:
?a
True if any characters have been included in the prompt so far.
?bX
True if the byte offset of the specified line is known.
?B
True if the size of current input file is known.
?c
True if the text is horizontally shifted (%c is not zero).
?dX
True if the page number of the specified line is known.
?e
True if at end-of-file.
?f
True if there is an input filename (that is, if input is not a
pipe).
?lX
True if the line number of the specified line is known.
?L
True if the line number of the last line in the file is known.
?m
True if there is more than one input file.
?n
True if this is the first prompt in a new input file.
?pX
True if the percent into the current input file, based on byte
offsets, of the specified line is known.
?PX
True if the percent into the current input file, based on line
numbers, of the specified line is known.
?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(file %i of %m) ..?e(END) ?x- Next\: %x..%t
This prints the filename if this is the first prompt in a file,
followed by the "file N of N" message if there is more than one
input file. Then, if we are at end-of-file, the string "(END)" is
printed followed by the name of the next file, if there is one.
Finally, any trailing spaces are truncated. This is the default
prompt. For reference, here are the defaults for the other two
prompts (-m and -M respectively). Each is broken into two lines
here for readability only.
?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.:
?pB%pB\%:byte %bB?s/%s...%t
?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. :
byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t
And here is the default message produced by the = command:
?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. .
byte %bB?s/%s. ?e(END) :?pB%pB\%..%t
The prompt expansion features are also used for another purpose:
if an environment variable LESSEDIT is defined, it is used as the
command to be executed when the v command is invoked. The
LESSEDIT string is expanded in the same way as the prompt
strings. The default value for LESSEDIT is:
%E ?lm+%lm. %f
Note that this expands to the editor name, followed by a + and
the line number, followed by the file name. If your editor does
not accept the "+linenumber" syntax, or has other differences in
invocation syntax, the LESSEDIT variable can be changed to modify
this default.
security
When the environment variable LESSSECURE is set to 1, less
runs in a "secure" mode. This means these features are disabled:
!
the shell command
|
the pipe command
:e
the examine command.
v
the editing command
s -o
log files
-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.
see also
lesskey
author
Mark Nudelman
Send bug reports or comments to <bug-less[:at:]gnu[:dot:]org>
See http://www.greenwoodsoftware.com/less/bugs.html for the
latest list of known bugs in less.
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.