less - phpMan

LESS(1) LESS(1)

NAME
less - opposite of more

SYNOPSIS
less -?
less --help
less -V
less --version
less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
[-b space] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
[-# shift] [+[+]cmd] [--] [filename]...
(See the OPTIONS section for alternate option syntax with long option names.)

DESCRIPTION
Less is a program similar to more (1), but which allows backward movement in the
file as well as forward movement. Also, less does not have to read the entire
input file before starting, so with large input files it starts up faster than text
editors like vi (1). Less uses termcap (or terminfo on some systems), so it can
run on a variety of terminals. There is even limited support for hardcopy termi-
nals. (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 num-
ber, 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 com-
mands, 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 speci-
fied, 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 spe-
cial job control character.

u or ^U
Scroll backward N lines, default one half of the screen size. If N is spec-
ified, 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 let-
ter.

’ (Single quote.) Followed by any lowercase letter, returns to the position
which was previously marked with that letter. Followed by another single
quote, returns to the position at which the last "large" movement command
was executed. Followed by a ^ or $, jumps to the beginning or end of the
file respectively. Marks are preserved when a new file is examined, so the
’ command can be used to switch between input files.

^X^X Same as single quote.

/pattern
Search forward in the file for the N-th line containing the pattern. N
defaults to 1. The pattern is a regular expression, as recognized by the
regular expression library supplied by your system. The search starts at
the 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 sim-
ple 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 cur-
rent 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 previ-
ous 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 con-
tains 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 con-
tains 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 char-
acter. 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 speci-
fied, the N-th previous file is examined.

:x Examine the first file in the command line list. If a number N is speci-
fied, 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 pos-
sible, 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 mes-
sage 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 set-
ting. (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 describ-
ing 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 pro-
cessor.

| <m> shell-command
<m> represents any mark letter. Pipes a section of the input file to the
given shell command. The section of the file to be piped is between the
first line on the current screen and the position marked by the letter. <m>
may also be ^ or $ to indicate beginning or end of file respectively. If
<m> is . or newline, the current screen is piped.

s filename
Save the input to a file. This only works if the input is a pipe, not an
ordinary file.

OPTIONS
Command line options are described below. Most options may be changed while less
is running, via the "-" command.

Most options may be given in one of two forms: either a dash followed by a single
letter, or two dashes followed by a long option name. A long option name may be
abbreviated as long as the abbreviation is unambiguous. For example, --quit-at-eof
may be abbreviated --quit, but not --qui, since both --quit-at-eof and --quiet
begin with --qui. Some long option names are in uppercase, such as --QUIT-AT-EOF,
as distinct from --quit-at-eof. Such option names need only have their first let-
ter capitalized; the remainder of the name may be in either case. For example,
--Quit-at-eof is equivalent to --QUIT-AT-EOF.

Options are also taken from the environment variable "LESS". For example, to avoid
typing "less -options ..." each time less is invoked, you might tell csh:

setenv LESS "-options"

or if you use sh:

LESS="-options"; export LESS

On MS-DOS, you don’t need the quotes, but you should replace any percent signs in
the options string by double percent signs.

The environment variable is parsed before the command line, so command line options
override the LESS environment variable. If an option appears in the LESS variable,
it can be reset to its default value on the command line by beginning the command
line option with "-+".

For options like -P or -D which take a following string, a dollar sign ($) must be
used to signal the end of the string. For example, to set two -D options on MS-
DOS, you must have a dollar sign between them, like this:

LESS="-Dn9.1$-Ds4.1"

-? or --help
This option displays a summary of the commands accepted by less (the same as
the h command). (Depending on how your shell interprets the question mark,
it may be necessary to quote the question mark, thus: "-\?".)

-a or --search-skip-screen
Causes searches to start after the last line displayed on the screen, thus
skipping all lines displayed on the screen. By default, searches start at
the second line on the screen (or after the last found line; see the -j
option).

-bn or --buffers=n
Specifies the amount of buffer space less will use for each file, in units
of kilobytes (1024 bytes). By default 64K of buffer space is used for each
file (unless the file is a pipe; see the -B option). The -b option speci-
fies 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 automati-
cally 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 termi-
nal 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=stand-
out, 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 com-
mand. 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 com-
mands.

-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 consid-
ered 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.

-K or --quit-on-intr
Causes less to exit immediately when an interrupt character (usually ^C) is
typed. Normally, an interrupt character causes less to stop whatever it is
doing and return to its command prompt.

-L or --no-lessopen
Ignore the LESSOPEN environment variable (see the INPUT PREPROCESSOR section
below). This option can be set from within less, but it will apply only to
files opened subsequently, not to the file which is currently open.

-m or --long-prompt
Causes less to prompt verbosely (like more), with the percent into the file.
By default, less prompts with a colon.

-M or --LONG-PROMPT
Causes less to prompt even more verbosely than more.

-n or --line-numbers
Suppresses line numbers. The default (to use line numbers) may cause less
to run more slowly in some cases, especially with a very large input file.
Suppressing line numbers with the -n option will avoid this problem. Using
line numbers means: the line number will be displayed in the verbose prompt
and in the = command, and the v command will pass the current line number to
the editor (see also the discussion of LESSEDIT in PROMPTS below).

-N or --LINE-NUMBERS
Causes a line number to be displayed at the beginning of each line in the
display.

-ofilename or --log-file=filename
Causes less to copy its input to the named file as it is being viewed. This
applies only when the input file is a pipe, not an ordinary file. If the
file already exists, less will ask for confirmation before overwriting it.

-Ofilename or --LOG-FILE=filename
The -O option is like -o, but it will overwrite an existing file without
asking for confirmation.

If no log file has been specified, the -o and -O options can be used from
within less to specify a log file. Without a file name, they will simply
report the name of the log file. The "s" command is equivalent to specify-
ing -o from within less.

-ppattern or --pattern=pattern
The -p option on the command line is equivalent to specifying +/pattern;
that is, it tells less to start at the first occurrence of pattern in the
file.

-Pprompt or --prompt=prompt
Provides a way to tailor the three prompt styles to your own preference.
This option would normally be put in the LESS environment variable, rather
than being typed in with each less command. Such an option must either be
the last option in the LESS variable, or be terminated by a dollar sign.
-Ps followed by a string changes the default (short) prompt to that string.
-Pm changes the medium (-m) prompt. -PM changes the long (-M) prompt. -Ph
changes the prompt for the help screen. -P= changes the message printed by
the = command. -Pw changes the message printed while waiting for data (in
the F command). All prompt strings consist of a sequence of letters and
special escape sequences. See the section on PROMPTS for more details.

-q or --quiet or --silent
Causes moderately "quiet" operation: the terminal bell is not rung if an
attempt is made to scroll past the end of the file or before the beginning
of the file. If the terminal has a "visual bell", it is used instead. The
bell will be rung on certain other errors, such as typing an invalid charac-
ter. 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 dis-
play problems may result, such as long lines being split in the wrong place.

-R or --RAW-CONTROL-CHARS
Like -r, but only ANSI "color" escape sequences are output in "raw" form.
Unlike -r, the screen appearance is maintained correctly in most cases.
ANSI "color" escape sequences are sequences of the form:

ESC [ ... m

where the "..." is zero or more color specification characters For the pur-
pose of keeping track of screen appearance, ANSI color escape sequences are
assumed to not move the cursor. You can make less think that characters
other than "m" can end ANSI color escape sequences by setting the environ-
ment variable LESSANSIENDCHARS to the list of characters which can end a
color escape sequence. And you can make less think that characters other
than the standard ones may appear between the ESC and the m by setting the
environment variable LESSANSIMIDCHARS to the list of characters which can
appear.

-s or --squeeze-blank-lines
Causes consecutive blank lines to be squeezed into a single blank line.
This is useful when viewing nroff output.

-S or --chop-long-lines
Causes lines longer than the screen width to be chopped 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 remain-
der 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 previ-
ously built by ctags (1) or an equivalent command. If the environment vari-
able LESSGLOBALTAGS is set, it is taken to be the name of a command compati-
ble 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 charac-
ters; 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 char-
acters; 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 spe-
cially: the overstruck text is printed using the terminal’s hardware bold-
face capability. Other backspaces are deleted, along with the preceding
character. Carriage returns immediately followed by a newline are deleted.
other carriage returns are handled as specified by the -r option. Text
which is overstruck or underlined can be searched for if neither -u nor -U
is in effect.

-V or --version
Displays the version number of less.

-w or --hilite-unread
Temporarily highlights the first "new" line after a forward movement of a
full page. The first "new" line is the line immediately following the line
previously at the bottom of the screen. Also highlights the target line
after a g or p command. The highlight is removed at the next command which
causes movement. The entire line is highlighted, unless the -J option is in
effect, in which case only the status column is highlighted.

-W or --HILITE-UNREAD
Like -w, but temporarily highlights the first new line after any forward
movement command larger than one line.

-xn,... or --tabs=n,...
Sets tab stops. If only one n is specified, tab stops are set at multiples
of n. If multiple values separated by commas are specified, tab stops are
set at those positions, and then continue with the same spacing as the last
two. For example, -x9,17 will set tabs at positions 9, 17, 25, 33, etc.
The default for n is 8.

-X or --no-init
Disables sending the termcap initialization and deinitialization strings to
the terminal. This is sometimes desirable if the deinitialization string
does something unnecessary, like clearing the screen.

--no-keypad
Disables sending the keypad initialization and deinitialization strings to
the terminal. This is sometimes useful if the keypad strings make the
numeric keypad behave in an undesirable manner.

-yn or --max-forw-scroll=n
Specifies a maximum number of lines to scroll forward. If it is necessary
to scroll forward more than n lines, the screen is repainted instead. The
-c or -C option may be used to repaint from the top of the screen if
desired. By default, any forward movement causes scrolling.

-[z]n or --window=n
Changes the default scrolling window size to n lines. The default is one
screenful. The z and w commands can also be used to change the window size.
The "z" may be omitted for compatibility with more. If the number n is neg-
ative, it indicates n lines less than the current screen size. For example,
if the screen is 24 lines, -z-4 sets the scrolling window to 20 lines. If
the screen is resized to 40 lines, the scrolling window automatically
changes to 36 lines.

-"cc or --quotes=cc
Changes the filename quoting character. This may be necessary if you are
trying to name a file which contains both spaces and quote characters. Fol-
lowed by a single character, this changes the quote character to that char-
acter. Filenames containing a space should then be surrounded by that char-
acter rather than by double quotes. Followed by two characters, changes the
open quote to the first character, and the close quote to the second charac-
ter. 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 speci-
fied 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 back-
slash 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 com-
pleted 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 envi-
ronment 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 environ-
ment 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/sys-
less. (However, if less was built with a different sysconf directory than
/usr/local/etc, that directory is where the sysless file is found.) On MS-DOS and
Windows systems, the system-wide lesskey file is c:\_sysless. On OS/2 systems, the
system-wide lesskey file is c:\sysless.ini.

INPUT PREPROCESSOR
You may define an "input preprocessor" for less. Before less opens a file, it
first gives your input preprocessor a chance to modify the way the contents of the
file are displayed. An input preprocessor is simply an executable program (or
shell script), which writes the contents of the file to a different file, called
the replacement file. The contents of the replacement file are then displayed in
place of the contents of the original file. However, it will appear to the user as
if the original file is opened; that is, less will display the original filename as
the name of the current file.

An input preprocessor receives one command line argument, the original filename, as
entered by the user. It should create the replacement file, and when finished,
print the name of the replacement file to its standard output. If the input pre-
processor 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 com-
mand 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 environ-
ment variable to a command line which will invoke your input postprocessor. It may
include two occurrences of the string "%s"; the first is replaced with the original
name of the file and the second with the name of the replacement file, which was
output by LESSOPEN.

For example, on many Unix systems, these two scripts will allow you to keep files
in compressed format, but still let less view them directly:

lessopen.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -
if [ -s /tmp/less.$$ ]; then
echo /tmp/less.$$
else
rm -f /tmp/less.$$
fi
;;
esac

lessclose.sh:
#! /bin/sh
rm $2

To use these scripts, put them both where they can be executed and set
LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More complex
LESSOPEN and LESSCLOSE scripts may be written to accept other types of compressed
files, and so on.

It is also possible to set up an input preprocessor to pipe the file data directly
to less, rather than putting the data into a replacement file. This avoids the
need to decompress the entire file before starting to view it. An input preproces-
sor that works this way is called an input pipe. An input pipe, instead of writing
the name of a replacement file on its standard output, writes the entire contents
of the replacement file on its standard output. If the input pipe does not write
any characters on its standard output, then there is no replacement file and less
uses the original file, as normal. To use an input pipe, make the first character
in the LESSOPEN environment variable a vertical bar (|) to signify that the input
preprocessor is an input pipe.

For example, on many Unix systems, this script will work like the previous example
scripts:

lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
;;
esac

To use this script, put it where it can be executed and set LESSOPEN="|lesspipe.sh
%s". When an input pipe is used, a LESSCLOSE postprocessor can be used, but it is
usually not necessary since there is no replacement file to clean up. In this
case, the replacement file name passed to the LESSCLOSE postprocessor is "-".

NATIONAL CHARACTER SETS
There are three types of characters in the input file:

normal characters
can be displayed directly to the screen.

control characters
should not be displayed directly, but are expected to be found in ordinary
text files (such as backspace and tab).

binary characters
should not be displayed directly and are not expected to be found in text
files.

A "character set" is simply a description of which characters are to be considered
normal, control, and binary. The LESSCHARSET environment variable may be used to
select a character set. Possible values for LESSCHARSET are:

ascii BS, TAB, NL, CR, and formfeed are control characters, all chars with values
between 32 and 126 are normal, and all others are binary.

iso8859
Selects an ISO 8859 character set. This is the same as ASCII, except char-
acters 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 LESS-
CHARSET=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.

windows
Selects a character set appropriate for Microsoft Windows (cp 1251).

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 neces-
sarily represent any real character set.)

This table shows the value of LESSCHARDEF which is equivalent to each of the possi-
ble values for LESSCHARSET:

ascii 8bcccbcc18b95.b
dos 8bcccbcc12bc5b95.b.
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
191.b
iso8859 8bcccbcc18b95.33b.
koi8-r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb

If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings "UTF-8",
"UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or LANG environment vari-
ables, 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 set-
ting 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 brack-
ets. 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 default if
no LESSBINFMT is specified is "*s<%02X>". Warning: the result of expanding the
character via LESSBINFMT must be less than 31 characters.

When the character set is utf-8, the LESSUTFBINFMT environment variable acts simi-
larly to LESSBINFMT but it applies to Unicode code points that were successfully
decoded but are unsuitable for display (e.g., unassigned code points). Its default
value is "<U+%04lX>". Note that LESSUTFBINFMT and LESSBINFMT share their display
attribute setting ("*x") so specifying one will affect both; LESSUTFBINFMT is read
after LESSBINFMT so its setting, if any, will have priority. Problematic octets in
a UTF-8 file (octets of a truncated sequence, octets of a complete but non-shortest
form sequence, illegal octets, and stray trailing octets) are displayed individu-
ally using LESSBINFMT so as to facilitate diagnostic of how the UTF-8 file is ill-
formed.

PROMPTS
The -P option allows you to tailor the prompt to your preference. The string given
to the -P option replaces the specified prompt string. Certain characters in the
string are interpreted specially. The prompt mechanism is rather complicated to
provide flexibility, but the ordinary user need not understand the details of
constructing personalized prompt strings.

A percent sign followed by a single character is expanded according to what the
following character is:

%bX Replaced by the byte offset into the current input file. The b is followed
by a single character (shown as X above) which specifies the line whose byte
offset is to be used. If the character is a "t", the byte offset of the top
line in the display is used, an "m" means use the middle line, a "b" means
use the bottom line, a "B" means use the line just after the bottom line,
and a "j" means use the "target" line, as specified by the -j option.

%B Replaced by the size of the current input file.

%c Replaced by the column number of the text appearing in the first column of
the screen.

%dX Replaced by the page number of a line in the input file. The line to be
used is determined by the X, as with the %b option.

%D Replaced by the number of pages in the input file, or equivalently, the page
number of the last line in the input file.

%E Replaced by the name of the editor (from the VISUAL environment variable, or
the EDITOR environment variable if VISUAL is not defined). See the discus-
sion 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 char-
acters 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 charac-
ters (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 sys-
tems).

LANG Language for determining the character set.

LC_CTYPE
Language for determining the character set.

LESS Options which are passed to less automatically.

LESSANSIENDCHARS
Characters which may end an ANSI color escape sequence (default "m").

LESSANSIMIDCHARS
Characters which may appear between the ESC character and the end character
in an ANSI color escape sequence (default "0123456789;[?!"’#%()*+ ".

LESSBINFMT
Format for displaying non-printable, non-control characters.

LESSCHARDEF
Defines a character set.

LESSCHARSET
Selects a predefined character set.

LESSCLOSE
Command line to invoke the (optional) input-postprocessor.

LESSECHO
Name of the lessecho program (default "lessecho"). The lessecho program is
needed to expand metacharacters, such as * and ?, in filenames on Unix sys-
tems.

LESSEDIT
Editor prototype string (used for the v command). See discussion under
PROMPTS.

LESSGLOBALTAGS
Name of the command used by the -t option to find global tags. Normally
should be set to "global" if your system has the global (1) command. If not
set, global tags are not used.

LESSHISTFILE
Name of the history file used to remember search commands and shell commands
between invocations of less. If set to "-", a history file is not used.
The default is "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and
Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" on OS/2 sys-
tems.

LESSHISTSIZE
The maximum number of commands to save in the history file. The default is
100.

LESSKEY
Name of the default lesskey(1) file.

LESSKEY_SYSTEM
Name of the default system-wide lesskey(1) file.

LESSMETACHARS
List of characters which are considered "metacharacters" by the shell.

LESSMETAESCAPE
Prefix which less will add before each metacharacter in a command sent to
the shell. If LESSMETAESCAPE is an empty string, commands containing
metacharacters will not be passed to the shell.

LESSOPEN
Command line to invoke the (optional) input-preprocessor.

LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.

LESSSEPARATOR
String to be appended to a directory name in filename completion.

LESSUTFBINFMT
Format for displaying non-printable Unicode code points.

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 vari-
ables.)

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).