NAME¶
less - opposite of more
SYNOPSIS¶
less -?
less --help
less -V
less --version
less [-[+]aBcCdeEfFgGiIJLmMnNqQrRsSuUVwWXYZ~]
[-b space] [-h lines] [-j line] [-k keyfile]
[-K character set] [-{oO} logfile]
[-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z]
lines]
[-# shift] [+[+]cmd] [--] [filename]...
(See the OPTIONS section for alternate option syntax with long option names.)
DESCRIPTION¶
Less is a program similar to
more (1), but which allows backward
movement in the file as well as forward movement. Also,
less does not
have to read the entire input file before starting, so with large input files
it starts up faster than text editors like
vi (1).
Less uses
termcap (or terminfo on some systems), so it can run on a variety of
terminals. There is even limited support for hardcopy terminals. (On a
hardcopy terminal, lines which should be printed at the top of the screen are
prefixed with a caret.)
Commands are based on both
more and
vi. Commands may be preceded
by a decimal number, called N in the descriptions below. The 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.
- @
- Rotate the code recognition method of the current file. Enhanced
less has 7 methods for recognition, default (which is chosen by the
JLESSCHARSET environment variable), japanese, ujis, sjis, iso8, noconv and
none.
- -
- 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.
Options are also taken from the environment variable "LESS" and
"JLESS".
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 and JLESS environment variables. If an option
appears in the LESS and JLESS variables, 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.
- -L or --no-lessopen
- Ignore the LESSOPEN environment variable (see the INPUT PREPROCESSOR
section below). This option can be set from within less, but it
will apply only to files opened subsequently, not to the file which is
currently open.
- -Kcharset
- Causes less to use this charset instead of a charset defined in the
JLESSCHARSET or LESSCHARSET environment variable.
- -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 and JLESS environment
variables, rather than being typed in with each less command. Such
an option must either be the last option in the LESS and JLESS variables,
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 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 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.
- -Y
- Causes mark characters to be used to represent wrong characters. By
default, such wrong characters displayed as binary.
- -[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.
- -Z
- Causes to give priority to the SJIS over the UJIS if a
"japanese" was selected by the JLESSCHARSET environment
variable. The default value is to give priority to the UJIS over the
SJIS.
- -"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.
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 JLESSCHARSET and LESSCHARSET
environment variables may be used to select a character set. There is no
difference between them in program of
less. But I suppose you should
use the JLESSCHARSET environment variable because not enhanced
less
will make errors if you use enhanced character set in your LESSCHARSET
environment variable. Possible values for them 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.
And possible values for only JLESSCHARSET are:
- iso7
- Multi character sets with the ISO 2022 code extension techniques in 7 bits
are assumed. Characters with values between 128 and 255 are treated as
binary. The level of implementation of Less is level 3 of ISO
2022.
- iso8
- Multi character sets with the ISO 2022 code extension techniques in 8 bits
are assumed. The level of implementation of Less is level 3 of ISO
2022.
- jis
- Only Japanese character sets with the ISO 2022 code extension techniques
in 7 bits are assumed.
- ujis
- If characters has values between 32 and 127, the ASCII character set are
assumed. If characters has values between 162 and 254, the JISX 0208
character set, a right half of the JISX 0201 character set and the JISX
0212 character set with the UJIS coding are assumed. Otherwise, characters
are treated as binary.
- euc
- Same as ujis.
- sjis
- If characters has values between 32 and 127, the ASCII character set are
assumed. If characters has values between 128 and 252, the JISX 0208
character set and a right half of the JISX 0201 character set are assumed.
Otherwise, characters are treated as binary.
- japanese
- All Japanese character sets, jis, ujis and sjis, are assumed. But
less output only the jis.
Japanese has several code sets (not character sets). Thus
less must
convert among them to display them correctly. Possible values with this
conversion for only JLESSCHARSET are:
- ujis-iso7
- The ujis and iso7 are assumend. But less output only the iso7.
- euc-iso7
- Same as ujis-iso7.
- sjis-iso7
- The sjis and iso7 are assumend. But less output only the iso7.
- ujis-jis
- The ujis and jis are assumend. But less output only the jis.
- euc-jis
- Same as ujis-jis.
- sjis-jis
- The sjis and jis are assumend. But less output only the jis.
- jis-ujis
- The jis and ujis are assumend. But less output only the ujis.
- jis-euc
- Same as jis-ujis.
- jis-sjis
- The jis and sjis are assumend. But less output only the sjis.
- japanese-iso7
- The japanese and iso7 are assumend. But less output only the
iso7.
- japanese-jis
- The japanese is assumend. But less output only the jis. Same as
japanese.
- japanese-ujis
- The japanese is assumend. But less output only the ujis.
- japanese-euc
- Same as japanese-ujis.
- japanese-sjis
- The japanese is assumend. But less output only the sjis.
- ujis-sjis
- The ujis is assumend. But less output only the sjis.
- euc-sjis
- Same as ujis-sjis.
- sjis-ujis
- The sjis is assumend. But less output only the ujis.
- sjis-euc
- Same as sjis-ujis.
Other way to select a character set is to use the LANG environment variable. If
it start with "ja_JP" or "japan",
less read all
Japanese coded characters as some Japanese character set, and a rest of the
LANG environment variable specify output coding.
The ISO 2022 code extension techniques define 4 planes to display many character
sets easy. Default setting of planes is selected by the JLESSPLANESET
environment variable. If the JLESSPLANESET vriable is equal to
"japanese", "ujis" or "euc",
less treat
g1 plane as JISX 0208, g2 plane as JISX 0201 right half, g3 plane as JISX
0212. If it is equal to "latin1", "latin2",
"latin3", "latin4", "greek", "arabic",
"hebrew", "cyrillic" or "latin5",
less
treat g1 plane as one of ISO 8859. Otherwise,
less try to parse the
JLESSPLANESET variable as real escape sequences for setting up, and
"\e" in JLESSPLANESET is treated as escape code when parsing.
Less understand almost all escape sequence about character set in the ISO
2022 code extension techniques. There are many escape sequences to select the
character set. On the one hand,
less output only 6 escape sequences to
select a character set: '^[(', '^[-', '^[$(', '^[$-', '^N' and '^O'. It means
less is friendly to a terminal and a terminal emulator.
And there is special "character set" for keyboard inputs. The
JLESSKEYCHARSET environment variable is used for such purpose. Possible values
of it are equal to the JLESSCHARSET environment variable.
If the LESSCHARSET environment variable is not set, the default character set is
latin1. However, if the string "UTF-8" is found in the LC_ALL,
LC_CTYPE or LANG environment variables, then the default character set is
utf-8 instead.
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.
- %K
- Replaced by the name of the last non ASCII character set or code set.
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.
- JLESS
- same as the LESS environment variable.
- 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.
- JLESSCHARSET
- Selects a predefined character set.
- LESSCHARSET
- Selects a predefined character set if JLESSCHARSET is not defined.
- JLESSKEYCHARSET
- Selects a predefined character set for keyboard inputs.
- JLESSPLANESET
- Selects a predefined plane set of the ISO 2022 code extension
techniques.
- 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) 2002 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 <markn@greenwoodsoftware.com>
Send bug reports or comments to the above address or to bug-less@gnu.org.
For more information, see the less homepage at
http://www.greenwoodsoftware.com/less.
PATCH¶
Copyright (c) 1994-2005 Kazushi (Jam) Marukawa, Japanized routines only
Comments about this part to: jam@pobox.com
You may distribute under the terms of the Less License.