NAME
less - opposite of more
SYNOPSIS
less -?
less --help
less -V
less --version
less [-[+]aBcCdeEfFgGiIJmMnNqQrRsSuUVwWX]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[+[+]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 number is used by some commands,
as indicated.
COMMANDS
In the following descriptions, ^X means control-X. ESC stands for the ESCAPE
key; for example ESC-v means the two character sequence "ESCAPE", then "v".
h or H
Help: display a summary of these commands. If you forget all the other commands,
remember this one.
SPACE or ^V or f or ^F
Scroll forward N lines, default one window (see option -z below). If N is more
than the screen size, only the final screenful is displayed. Warning: some
systems use ^V as a special literalization 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.
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.)
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.
{
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 ed. The search
starts at the second line displayed (but see the -a and -j options, which change
this).
Certain characters are special if entered at the beginning of the pattern; they
modify the type of search rather than become part of the pattern:
^N 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.)
: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 RETURN after typing the option name. A ^P
immediately after the second dash suppresses printing of a message describing
the new setting, as in the - command.
-+
Followed by one of the command line option letters this will reset the option to
its default setting and print a message describing the new setting. (The "-+X"
command does the same thing as "-+X" on the command line.) This does not work
for string-valued options.
--+
Like the -+ command, but takes a long option name rather than a single option
letter.
-!
Followed by one of the command line option letters, this will reset the option
to the "opposite" of its default setting and print a message describing the new
setting. This does not work for numeric or string-valued options.
--!
Like the -! command, but takes a long option name rather than a single option
letter.
_
(Underscore.) Followed by one of the command line option letters, this will
print a message describing the current setting of that option. The setting of
the option is not changed.
__
(Double underscore.) Like the _ (underscore) command, but takes a long option
name rather than a single option letter. You must press RETURN after typing the
option name.
+cmd
Causes the specified cmd to be executed each time a new file is 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.
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 "-+".
For options like -P or -D which take a following string, a dollar sign ($) must
be used to signal the end of the string. For example, to set two -D options on
MS-DOS, you must have a dollar sign between them, like this:
LESS="-Dn9.1$-Ds4.1"
-? 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
Causes searches to start after the last line displayed on the screen, thus
skipping all lines displayed on the screen. By default, searches start at the
second line on the screen (or after the last found line; see the -j option).
-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 is 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 file 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
The -C option is like -c, but the screen is cleared before it is repainted.
-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.0.
-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.
-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. A
target line is the object of a text search, tag search, jump to a line number,
jump to a file percentage, or jump to a marked position. The screen line is
specified by a number: the top line on the screen is 1, the next is 2, and so
on. The number may be negative to specify a line relative to the bottom of the
screen: the bottom line on the screen is -1, the second to the bottom is -2, and
so on. If the -j option is used, searches begin at the line immediately after
the target line. For example, if "-j4" is used, the target line is the fourth
line on the screen, so searches begin at the fifth line on the screen.
-J 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.
-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 tries to keep track of the screen appearance where possible. This
works only if the input consists of normal text and possibly some ANSI "color"
escape sequences, which are sequences of the form:
ESC [ ... m
where the "..." is zero or more characters other than "m". For the purpose of
keeping track of screen appearance, all control characters and all ANSI color
escape sequences are assumed to not move the cursor. You can make less think
that characters other than "m" can end ANSI color escape sequences by setting
the environment variable LESSANSIENDCHARS to the list of characters which can
end a color escape sequence.
-s 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 rather than folded. That
is, the remainder of a long line is simply discarded. The default is to fold
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.
--no-keypad
Disables sending the keypad initialization and deinitialization strings to the
terminal. This is sometimes useful if the keypad strings make the numeric keypad
behave in an undesirable manner.
-yn 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 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.
--
A command line argument of "--" marks the end of option arguments. Any arguments
following this are interpreted as filenames. This can be useful when viewing a
file whose name begins with a "-" or "+".
+
If a command line option begins with +, the remainder of that option is taken to
be an initial command to less. For example, +G tells less to start at the end of
the file rather than the beginning, and +/xyz tells it to start at the first
occurrence of "xyz" in the file. As a special case, +<number> acts like
+<number>g; that is, it starts the display at the specified line number
(however, see the caveat under the "g" command above). If the option starts with
++, the initial command applies to every file being viewed, not just the first
one. The + command described previously may also be used to set (or change) an
initial command for every file.
LINE EDITING
When entering command line at the bottom of the screen (for example, a filename
for the :e command, or the pattern for a search command), certain keys can be
used to manipulate the command line. Most commands have an alternate form in [
brackets ] which can be used if a key does not exist on a particular keyboard.
(The bracketed forms do not work in the MS-DOS version.) Any of these special
keys may be entered literally by preceding it with the "literal" character,
either ^V or ^A. A backslash itself may also be entered literally by entering
two backslashes.
LEFTARROW [ ESC-h ]
Move the cursor one space to the left.
RIGHTARROW [ ESC-l ]
Move the cursor one space to the right.
^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
(That is, CONTROL and LEFTARROW simultaneously.) Move the cursor one word to the
left.
^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
(That is, CONTROL and RIGHTARROW simultaneously.) Move the cursor one word to
the right.
HOME [ ESC-0 ]
Move the cursor to the beginning of the line.
END [ ESC-$ ]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or cancel the command if the
command line is empty.
DELETE or [ ESC-x ]
Delete the character under the cursor.
^BACKSPACE [ ESC-BACKSPACE ]
(That is, CONTROL and BACKSPACE simultaneously.) Delete the word to the left of
the cursor.
^DELETE [ ESC-X or ESC-DELETE ]
(That is, CONTROL and DELETE simultaneously.) Delete the word under the cursor.
UPARROW [ ESC-k ]
Retrieve the previous command line.
DOWNARROW [ ESC-j ]
Retrieve the next command line.
TAB
Complete the partial filename to the left of the cursor. If it matches more than
one filename, the first match is entered into the command line. Repeated TABs
will cycle 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.
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.
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 -c $1 >/tmp/less.$$ 2>/dev/null
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac
lessclose.sh:
#! /bin/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
;;
esac
To use this script, put it where it can be executed and set
LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE
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 "-".
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.
In special cases, it may be desired to tailor less to use a character set other
than the ones definable by LESSCHARSET. In this case, the 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 the string "UTF-8" is found
in the LC_ALL, LC_TYPE 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<%X>".
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.
%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.
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 are assumed to end an ANSI color escape sequence (default "m").
LESSBINFMT
Format for displaying non-printable, non-control characters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSCLOSE
Command line to invoke the (optional) input-postprocessor.
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.
LESSKEY
Name of the default lesskey(1) file.
LESSKEY_SYSTEM
Name of the default system-wide lesskey(1) file.
LESSMETACHARS
List of characters which are considered "metacharacters" by the shell.
LESSMETAESCAPE
Prefix which less will add before each metacharacter in a command sent to the
shell. If LESSMETAESCAPE is an empty string, commands containing metacharacters
will not be passed to the shell.
LESSOPEN
Command line to invoke the (optional) input-preprocessor.
LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.
LESSSEPARATOR
String to be appended to a directory name in filename completion.
LINES
Sets the number of lines on the screen. Takes precedence over the number of
lines specified by the TERM variable. (But if you have a windowing system which
supports TIOCGWINSZ or WIOCGETD, the window system's idea of the screen size
takes precedence over the LINES and COLUMNS environment variables.)
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)
WARNINGS
The = command and prompts (unless changed by -P) report the line numbers of the
lines at the top and bottom of the screen, but the byte and percent of the line
after the one at the bottom of the screen.
If the :e command is used to name more than one file, and one of the named files
has been viewed previously, the new files may be entered into the list in an
unexpected order.
On certain older terminals (the so-called "magic cookie" terminals), search
highlighting will cause an erroneous display. On such terminals, search
highlighting is disabled by default to avoid possible problems.
In certain cases, when search highlighting is enabled and a search pattern
begins with a ^, more text than the matching string may be highlighted. (This
problem does not occur when less is compiled to use the POSIX regular expression
package.)
When viewing text containing ANSI color escape sequences using the -R option,
searching will not find text containing an embedded escape sequence. Also,
search highlighting may change the color of some of the text which follows the
highlighted text.
On some systems, setlocale claims that ASCII characters 0 thru 31 are control
characters rather than binary characters. This causes less to treat some binary
files as ordinary, non-binary files. To workaround this problem, set the
environment variable LESSCHARSET to "ascii" (or whatever character set is
appropriate).
See http://www.greenwoodsoftware.com/less for the latest list of known bugs in
this version of less.
COPYRIGHT
Copyright (C) 2001 Mark Nudelman
less is part of the GNU project and is free software. You can redistribute it
and/or modify it under the terms of either (1) the GNU General Public License as
published by the Free Software Foundation; or (2) the Less License. See the file
README in the less distribution for more details regarding redistribution. You
should have received a copy of the GNU General Public License along with the
source for less; see the file COPYING. If not, write to the Free Software
Foundation, 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should
also have received a copy of the Less License; see the file LICENSE.
less is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE. See the GNU General Public License for more details.
AUTHOR
Mark Nudelman <[email protected]>
Send bug reports or comments to the above address or to [email protected].
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.