LESS(l) COMMAND REFERENCE LESS(l)
NAME
less - opposite of more
SYNOPSIS
less [-cdepstwmMqQuU] [-hn] [-b[fp]n] [-xn] [+cmd] [name]
...
DESCRIPTION
Less is a program similar to more (1), but which allows
backwards 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, 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
preceeded by a decimal number, called N in the descriptions
below. The number is used by some commands, as indicated.
COMMANDS
h Help: display a summary of these commands. If you
forget all the other commands, remember this one.
SPACE
Scroll forward N lines, default one screen. If N is
more than the screen size, only one screenful is
displayed.
f Same as SPACE.
b Scroll backward N lines, default one screen. If N is
more than the screen size, only one screenful is
displayed.
RETURN
Scroll forward N lines, default 1. If N is more than
the screen size, the entire N lines are displayed.
e Same as RETURN.
j Also the same as RETURN.
y Scroll backward N lines, default 1. If N is more than
the screen size, the entire N lines are displayed.
k Same as y.
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LESS(l) COMMAND REFERENCE LESS(l)
d Scroll forward N lines, default 10. If N is specified,
it becomes the new default for all d and u commands.
u Scroll backward N lines, default 10. If N is
specified, it becomes the new default for all d and u
commands.
r Repaint the screen.
R Repaint the screen, discarding any buffered input.
Useful if the file is changing while it is being
viewed.
g Go to line N in the file, default 1 (beginning of
file). (Warning: this may be slow if N is large.)
G Go to line N in the file, default the end of the file.
(Warning: this may be slow if standard input, rather
than a file, is being read.)
p Go to a position N percent into the file. N should be
between 0 and 100. (This is possible 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.)
% Same as p.
m Followed by any lowercase letter, marks the current
position with that letter.
' Followed by any lowercase letter, returns to the
position which was previously marked with that letter.
All marks are lost when a new file is examined.
/pattern
Search forward in the file for the N-th occurence of
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 -t
option, which changes this).
?pattern
Search backward in the file for the N-th occurence of
the pattern. The search starts at the line immediately
before the top line displayed.
n Repeat previous search, for N-th occurence of the last
pattern.
E Examine a new file. If the filename is missing, the
"current" file (see the N and P commands below) from
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LESS(l) COMMAND REFERENCE LESS(l)
the list of files in the command line is re-examined.
N Examine the next file (from the list of files given in
the command line). If a number N is specified (not to
be confused with the command N), the N-th next file is
examined.
P Examine the previous file. If a number N is specified,
the N-th previous file is examined.
= Prints the name of the file being viewed and the byte
offset of the bottom line being displayed. If
possible, it also prints the length of 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 toggle the setting of that option and
print a message describing the new setting.
V Prints the version number of less being run.
q Exits less.
The following two 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".
! shell-command
Invokes a shell to run the shell-command given.
OPTIONS
Command line options are described below. Options are also
taken from the environment variable "LESS". (The
environment variable is parsed before the command line, so
command line options override the LESS environment variable.
Options may be changed while less is running via the "-"
command.) For example, if you like more-style prompting, to
avoid typing "less -m ..." each time less is invoked, you
might tell csh:
setenv LESS m
or if you use sh:
LESS=m; export LESS
-s The -s flag causes consecutive blank lines to be
squeezed into a single blank line. This is useful when
viewing nroff output.
Printed 7/4/87 3
LESS(l) COMMAND REFERENCE LESS(l)
-t Normally, forward searches start just after the top
displayed line (that is, at the second displayed line).
Thus forward searches include the currently displayed
screen. The -t command line option causes forward
searches to start just after the bottom line displayed,
thus skipping the currently displayed screen.
-m Normally, less prompts with a colon. The -m command
line option causes less to prompt verbosely like more,
printing the file name and percent into the file.
-M The -M command line option causes less to prompt even
more verbosely than more.
-q Normally, if an attempt is made to scroll past the end
of the file or before the beginning of the file, the
terminal bell is rung to indicate this fact. The -q
command line option tells less not to ring the bell at
such times. If the terminal has a "visual bell", it is
used instead.
-Q Even if -q is given, less will ring the bell on certain
other errors, such as typing an invalid character. The
-Q command line option tells less to be quiet all the
time; that is, never ring the terminal bell. If the
terminal has a "visual bell", it is used instead.
-e Normally the only way to exit less is via the "q"
command. The -e command line option tells less to
automatically exit the second time it reaches end-of-
file.
-u If the -u command line option is given, backspaces are
treated as printable characters; that is, they are sent
to the terminal when they appear in the input.
-U If the -U command line option is given, backspaces are
printed as the two character sequence "^H". 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.
-w Normally, less uses a tilde character to represent
lines past the end of the file. The -w option causes
blank lines to be used instead.
-d Normally, less will complain if the terminal is dumb;
that is, lacks some important capability, such as the
ability to clear the screen or scroll backwards. The
-d flag suppresses this complaint (but does not
otherwise change the behavior of the program on a dumb
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LESS(l) COMMAND REFERENCE LESS(l)
terminal).
-p Normally, less will repaint the screen by scrolling
from the bottom of the screen. If the -p flag is set,
when less needs to change the entire display, it will
clear the screen and paint from the top line down.
-h Normally, less will scroll backwards when backwards
movement is necessary. The -h option specifies a
maximum number of lines to scroll backwards. If it is
necessary to move backwards more than this many lines,
the screen is repainted in a forward direction. (If
the terminal does not have the ability to scroll
backwards, -h0 is implied.)
-x The -xn command line option sets tab stops every n
positions. The default for n is 8.
-b The -bn command line option tells less to use a non-
standard buffer size. There are two standard (default)
buffer sizes, one is used when a file is being read and
the other when a pipe (standard input) is being read.
The current defaults are 5 buffers for files and 12 for
pipes. (Buffers are 1024 bytes.) The number n
specifies a different number of buffers to use. The -b
may be followed by "f", in which case only the file
default is changed, or by "p" in which case only the
pipe default is changed. Otherwise, both are changed.
-c Normally, when data is read by less, it is scanned to
ensure that bit 7 (the high order bit) is turned off in
each byte read, and to ensure that there are no null
(zero) bytes in the data (null bytes are turned into
"@" characters). If the data is known to be "clean",
the -c command line option will tell less to skip this
checking, causing an imperceptible speed improvement.
(However, if the data is not "clean", unpredicatable
results may occur.)
+ 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 occurence 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.
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LESS(l) COMMAND REFERENCE LESS(l)
BUGS
When used on standard input (rather than a file), you can
move backwards only a finite amount, corresponding to that
portion of the file which is still buffered.
Printed 7/4/87 6
%%index%%
na:72,59;
sy:131,414;
de:545,1714;2403,2024;4571,1279;
op:5850,775;6769,2650;9563,2729;12436,254;
%%index%%000000000131