less - opposite of more
SYNOPSIS
less -?
less [-[+]aBcCdeEfHimMnNqQrsSuUw]
[-b bufs] [-h lines] [-j line] [-k keyfile]
[-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
[-T tagfile] [-x tab] [-y lines] [-[z] lines]
[+[+]cmd] [filename]...
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 an up-
arrow.)
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. Warn-
ing: some systems use ^V as a special literaliza-
tion character.
z Like SPACE, but if N is specified, it becomes the
new window size.
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
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.
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
than a file, is being read.)
p or % Go to a position N percent into the file. N should
be between 0 and 100. (This works if standard
input is being read, but only if less has already
read to the end of the file. It is always fast,
but not always useful.)
{ 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,
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 con-
taining 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:
! Search for lines which do NOT match the pat-
tern.
* Search multiple files. That is, if the
search reaches the end of the current file
without finding a match, the search contin-
ues in the next file in the command line
list.
@ Begin the search at the first line of the
first file in the command line list, regard-
less of what is currently displayed on the
screen or the settings of the -a or -j
options.
?pattern
Search backward in the file for the N-th line con-
taining the pattern. The search starts at the line
immediately before the top line displayed.
tern.
* 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 com-
mand line list.
@ Begin the search at the last line of the
last file in the command line list, regard-
less of what is currently displayed on the
screen or the settings of the -a or -j
options.
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 modi-
fied by !, the search is made for the N-th line NOT
containing the pattern. If the previous search was
modified by *, the search continues in the next (or
previous) file if not satisfied in the current
file. There is no effect if the previous search
was modified by @.
N Repeat previous search, but in the reverse direc-
tion.
ESC-n Repeat previous search, but crossing file bound-
aries. The effect is as if the previous search
were modified by *.
ESC-N Repeat previous search, but in the reverse direc-
tion and crossing file boundaries.
: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
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.
^X^V or E
Same as :e. Warning: some systems use ^V as a spe-
cial literalization character.
: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.
= or ^G or :f
Prints some information about the file being
viewed, including its name and the line number and
byte offset of the bottom line being displayed. If
possible, it also prints the length of the file,
the number of lines in the file and the percent of
the file above the last displayed line.
- Followed by one of the command line option letters
(see below), this will change the setting of that
option and print a message describing the new set-
ting. 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 noth-
ing is changed.
-+ Followed by one of the command line option letters
(see below), 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
(see below), this will reset the option to the
"opposite" of its default setting and print a mes-
sage describing the new setting. (The "--X" com-
mand does the same thing as "-X" on the command
line.) This does not work for numeric or string-
valued options.
_ (Underscore.) Followed by one of the command line
option letters (see below), this will print a mes-
sage describing the current setting of that option.
The setting of the option is not changed.
+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 ZZ or ESC ESC
Exits less.
The following three 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 EDITOR, or defaults to "vi". 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. In
all cases, the shell is taken from the environment
variable SHELL, or defaults to "sh".
| <m> shell-command
<m> represents any mark letter. Pipes a section of
the input file to the given shell command. The
section of the file to be piped is between the
indicate beginning or end of file respectively. If
<m> is . or newline, the current screen is piped.
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". 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
The environment variable is parsed before the command
line, so command line options override the LESS environ-
ment variable. If an option appears in the LESS variable,
it can be reset to its default on the command line by
beginning the command line option with "-+".
A dollar sign ($) may be used to signal the end of an
option string. This is important only for options like -P
which take a following string.
-? This option displays a summary of the commands
accepted by less (the same as the h command). If
this option is given, all other options are
ignored, and less exits after the help screen is
viewed. (Depending on how your shell interprets
the question mark, it may be necessary to quote the
question mark, thus: "-\?".)
-a Causes searches to start after the last line dis-
played on the screen, thus skipping all lines dis-
played 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 Causes less to use a non-standard number of
buffers. Buffers are 1K, and by default 10 buffers
are used (except if data in coming from standard
input; see the -B option). The number n specifies
a different number of buffers to use.
-B Disables automatic allocation of buffers, so that
only the default number of buffers are used. If
more data is read than will fit in the buffers, the
oldest data is discarded. By default, when data is
-c 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 The -C option is like -c, but the screen is cleared
before it is repainted.
-d 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).
-e 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 Causes less to automatically exit the first time it
reaches end-of-file.
-f 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.
-hn Specifies a maximum number of lines to scroll back-
ward. 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 Causes searches to ignore case; that is, uppercase
and lowercase are considered identical. Also, text
which is overstruck or underlined can be searched
for. This option is ignored if any uppercase let-
ters appear in the search pattern.
-jn Specifies a line on the screen where "target" lines
are to be positioned. Target lines are the object
of text searches, tag searches, jumps to a line
number, jumps to a file percentage, and jumps 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 immedi-
screen, so searches begin at the fifth line on the
screen.
-kfilename
Causes less to open and interpret the named file as
a lesskey (1) file. Multiple -k options may be
specified. If a file called .less exists in the
user's home directory, this file is also used as a
lesskey file.
-m Causes less to prompt verbosely (like more), with
the percent into the file. By default, less
prompts with a colon.
-M Causes less to prompt even more verbosely than
more.
-n 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 flag 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 Causes a line number to be displayed at the begin-
ning of each line in the display.
-ofilename
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
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
The -p option on the command line is equivalent to
specifying +/pattern; that is, it tells less to
start at the first occurence of pattern in the
file.
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. -P
followed by a string changes the default (short)
prompt to that string. -Pm changes the medium (-m)
prompt to the string, and -PM changes the long (-M)
prompt. Also, -P= changes the message printed by
the = command to the given string. All prompt
strings consist of a sequence of letters and spe-
cial escape sequences. See the section on PROMPTS
for more details.
-q 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 Causes totally "quiet" operation: the terminal bell
is never rung.
-r 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
flag 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 charac-
ter). Thus, various display problems may result,
such as long lines being split in the wrong place.
-s Causes consecutive blank lines to be squeezed into
a single blank line. This is useful when viewing
nroff output.
-S Causes lines longer than the screen width to be
chopped rather than folded. That is, the remainder
of a long line is simply discarded. The default is
to fold long lines; that is, display the remainder
on the next line.
-ttag The -t option, followed immediately by a TAG, will
edit the file containing that tag. For this to
work, there must be a file called "tags" in the
current directory, which was previously built by
the ctags (1) command. This option may also be
equivalent to specifying -t from within less.
-Ttagsfile
Specifies a tags file to be used instead of "tags".
-u 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 Causes backspaces 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.
-w Causes blank lines to be used to represent lines
past the end of the file. By default, a tilde
character is used.
-xn Sets tab stops every n positions. The default for
n is 8.
-yn Specifies a maximum number of lines to scroll for-
ward. 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 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, as in "-n" for com-
patibility with more.
+ If a command line option begins with +, the remain-
der of that option is taken to be an initial com-
mand 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>
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.
KEY BINDINGS
You may define your own less commands by using the program
lesskey (1) to create a file called ".less" in your home
directory. This file specifies a set of command keys and
an action associated with each key. See the lesskey man-
ual page for more details.
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
cannot be displayed directly and are not expected
to be found in text files.
By default, less uses the ASCII character set. In the
ASCII character set, characters with values between 128
and 255 are treated as binary. The LESSCHARSET environ-
ment variable may be used to select another character set.
If it is set to the value "latin1", the ISO 8859/1 charac-
ter set is assumed. Latin-1 is the same as ASCII, except
characters between 128 and 255 are treated as normal char-
acters. The only valid values for LESSCHARSET currently
are "ascii" and "latin1".
In special cases, it may be desired to tailor less to use
a character set other than the ones definable by LESS-
CHARSET. In this case, the environment variable LESS-
CHARDEF can be used to define a character set. It should
be set to a string where each character in the string rep-
resents 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 repeti-
tion. 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
sarily represent any real character set.)
Setting LESSCHARDEF to "8bcccbcc18b95.b" is the same as
setting LESSCHARSET to "ascii". Setting LESSCHARDEF to
"8bcccbcc18b95.33b." is the same as setting LESSCHARSET to
"latin1".
Control and binary characters are displayed in blinking
mode. 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 dis-
played as an octal number preceded by a backslash. This
octal format can be changed by setting the LESSBINFMT
environment variable to a printf-style format string; the
default is '\%o'. The blinking mode display of control
and binary characters can be changed or disabled by pre-
ceding the LESSBINFMT format string with a "*" and one
character to select the mode: "*k" is blinking, "*d" is
bold, "*u" is underlined, and "*n" is normal (no special
display attribute). For example, if LESSBINFMT is
"*u[%x]", binary characters are displayed in underlined
hexadecimal surrounded by brackets.
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 ordi-
nary 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.
%E Replaced by the name of the editor (from the EDITOR
environment variable). See the discussion of the
LESSEDIT feature below.
%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. 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 any-
where.
%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 sin-
gle character acts like an "IF": depending on the follow-
ing 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.
?e True if at end-of-file.
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 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 file-
name 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 refer-
ence, here are the defaults for the other two prompts (-m
?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) ..?ltline %lt?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) .?ltline %lt?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 com-
mand 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 vari-
able can be changed to modify this default.
ENVIRONMENT VARIABLES
COLUMNS
Sets the number of columns on the screen. Takes
precedence over the number of columns specified by
the TERM variable.
EDITOR The name of the editor (used for the v command).
HOME Name of the user's home directory (used to find a
.less file).
LESS Flags which are passed to less automatically.
LESSBINFMT
Format for displaying non-printable, non-control
characters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSEDIT
LESSHELP
Name of the help file.
LINES Sets the number of lines on the screen. Takes
precedence over the number of lines specified by
the TERM variable.
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.
SEE ALSO
lesskey(1)
WARNINGS
The = command and prompts (unless changed by -P) report
the line number of the line at the top of the screen, but
the byte and percent of the line 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.
The handling of national character sets is nonstandard as
well as insufficient for multibyte characters. It will
probably change in a later release.
Release 1.1d7 of the Be OS
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