less, more - view files on a CRT
less | more -?
less | more --help
less | more -V
less | more --version
less | more [-[+]aBcCdeEfFgGiIJLmMnNqQrRsSuUVwWX~] [-b
space] [-h lines]
[-j line] [-k keyfile] [-o | -O logfile] [-p pattern]
[-P prompt]
[-t tag] [-T tagsfile] [-x tab,...] [-y lines] [-[z]
lines]
[-# shift] [+[+]cmd] [--] [filename ...]
less is a program similar to the traditional 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.)
This version of less also acts as more(1) if it is called as
more. In
this mode, the differences are in the prompt and that more
exits by default
when it gets to the end of the file. Commands are
based on both
traditional more and vi(1). Commands may be preceded by a
decimal number,
called N in the descriptions below. The number is used
by some commands,
as indicated.
In the following descriptions, ^X means control-X. ESC
stands for the
ESCAPE key; for example ESC-v means the two character sequence "ESCAPE",
then "v".
h | H
Help: display a summary of these commands. If you
forget all the
other commands, remember this one.
SPACE | ^V | f | ^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 [Toc] [Back]
Like SPACE, but scrolls a full screensful, even if it
reaches endof-file
in the process.
RETURN | ^N | e | ^E | j | ^J
Scroll forward N lines, default 1. The entire N lines
are displayed,
even if N is more than the screen size.
d | ^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 | ^B | 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 | ^Y | ^P | k | ^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 | ^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-) | 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-( | 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 | ^R | ^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 | < | ESC-<
Go to line N in the file, default 1 (beginning of
file). (Warning:
this may be slow if N is large.)
G | > | 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 | %
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 Nth 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(1). 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 | ! Search for lines which do NOT match the pattern.
^E | * 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 | @ 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 | ! Search for lines which do NOT match the pattern.
^E | * 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 | @ 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 [Toc] [Back]
Repeat previous search, but crossing file boundaries.
The effect
is as if the previous search were modified by *.
ESC-N [Toc] [Back]
Repeat previous search, but in the reverse direction
and crossing
file boundaries.
ESC-u [Toc] [Back]
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 | 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.
:t Go to the specified tag.
: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.
= | ^G | :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 stringvalued 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 | Q | :q | :Q | 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. The shell is taken from
the environment
variable SHELL, or defaults to "sh".
| <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.
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 if
the command
is less, or from the environment variable MORE if the command is more.
For example, to avoid typing "less -options ..." each time
less is invoked,
you might tell csh(1):
setenv LESS -options
or if you use sh(1):
LESS="-options"; export LESS
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 which take a following string, a dollar
sign ($) must
be used to signal the end of the string. For example, to
separate a
prompt value from any other options with dollar sign between
them:
LESS="-Ps--More--$-C -e"
-? | --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 | --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 | --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 | --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 | --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 | --CLEAR-SCREEN
The -C option is like -c, but the screen is cleared
before it is
repainted.
-d | --dumb (less only)
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. This option is on by default when invoked
as more.
-d (more only)
The -d option causes the default prompt to include the
basic directions
``[Press space to continue, 'q' to quit.]''.
The -d option
also causes the message ``[Press 'h' for instructions.]'' to be
displayed when an invalid command is entered (normally, the bell is
rung). This option is useful in environments where
users may not
be experienced with pagers.
-e | --quit-at-eof
Causes less to automatically exit the second time it
reaches endof-file.
By default, the only way to exit less is via
the "q" command.
-E | --QUIT-AT-EOF
Causes less to automatically exit the first time it
reaches end-offile.
-f | --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 | --quit-if-one-screen
Causes less to automatically exit if the entire file
can be displayed
on the first screen.
-g | --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 | --HILITE-SEARCH
The -G option suppresses all highlighting of strings
found by
search commands.
-hn | --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 | --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 | --IGNORE-CASE
Like -i, but searches ignore case even if the pattern
contains uppercase
letters.
-jn | --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 | --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 | --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.
-L | --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. When invoked as
more, the
LESSOPEN environment variable is ignored by default.
-m | --long-prompt
Causes less to prompt verbosely (like more), with the
percent into
the file. By default, less prompts with a colon.
-M | --LONG-PROMPT
Causes less to prompt even more verbosely than more.
-n | --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 | --LINE-NUMBERS
Causes a line number to be displayed at the beginning
of each line
in the display.
-ofilename | --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 | --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 | --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 | --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 | --quiet | --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 | --QUIET | --SILENT
Causes totally "quiet" operation: the terminal bell is
never rung.
-r | --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 | --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 | --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a
single blank
line. This is useful when viewing nroff(1) output.
-S | --chop-long-lines
Causes lines longer than the screen width to be
chopped rather than
folded. That is, the portion of a long line that does
not fit in
the screen width is not shown. The default is to fold
long lines;
that is, display the remainder on the next line.
-ttag | --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, 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 | --tag-file=tagsfile
Specifies a tags file to be used instead of "tags".
-u | --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 | --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 | --version
Displays the version number of less.
-w | --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 | --HILITE-UNREAD
Like -w, but temporarily highlights the first new line
after any
forward movement command larger than one line.
-xn,... | --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 | --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 | --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 | --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 | --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).
-~ | --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.
-# | --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.
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. 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-$]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or
cancel the
command if the command line is empty.
DELETE or [ESC-x]
Delete the character under the cursor.
^BACKSPACE [ESC-BACKSPACE]
(That is, CONTROL and BACKSPACE simultaneously.)
Delete the word
to the left of the cursor.
^DELETE [ESC-X or ESC-DELETE]
(That is, CONTROL and DELETE simultaneously.)
Delete the word
under the cursor.
UPARROW [ESC-k]
Retrieve the previous command line.
DOWNARROW [ESC-j]
Retrieve the next command line.
TAB Complete the partial filename to the left of the
cursor. If it
matches more than one filename, the first match is
entered into
the command line. Repeated TABs will cycle through
the other
matching filenames. If the completed filename is a
directory, a
"/" is appended to the filename. The environment
variable
LESSSEPARATOR can be used to specify a different
character to append
to a directory name.
BACKTAB [ESC-TAB]
Like TAB, but cycles in the reverse direction
through the matching
filenames.
^L Complete the partial filename to the left of the
cursor. If it
matches more than one filename, all matches are entered into the
command line (if they fit).
^U Delete the entire command line, or cancel the command if the command
line is empty. If you have changed your linekill character
to something other than ^U, that character is used
instead of ^U.
You may define your own less commands by using the program
lesskey(1) to
create a lesskey file. This file specifies a set of command
keys and an
action associated with each key. You may also use lesskey
to change the
line-editing keys (see LINE EDITING), and to set environment
variables.
If the environment variable LESSKEY is set, less uses that
as the name of
the lesskey file. Otherwise, less looks for a lesskey file
called
"$HOME/.less". See the lesskey(1) 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
OpenBSD, the system-wide lesskey file is /etc/sysless.
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, 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, 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 [Toc] [Back] 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>".
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 the 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 use
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