LESS(1) MINIX Version 1.3
LESS(1)
NAME less - opposite of more
SYNOPSIS less [-[+]aABcCdeEimMnqQuUsw] [-bN] [-hN]
[-xN] [-[z]N] [-P[mM=]string] [-[lL]logfile]
[+cmd] [-ttag] [filename]...
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 (or terminfo on some
systems), so it can run on a variety of termi-
nals. 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 de-
scriptions 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 Help: display a summary of these commands. If you
forget all the other commands, remember this one.
SPACE or f or ^F or ^V Scroll forward
N lines, default one window (see option -z below).
If N is more than the screen size, only the fi-
nal screenful is displayed. Warning: some systems
use ^V as a special literalization character.
b or ^B or ESC-v Scroll backward N
lines, default one window (see option -z be-
low). If N is more than the screen size, only the
final screenful is displayed.
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.
y or ^Y or ^P or k or ^K Scroll backward
N lines, default 1. The entire N lines are dis-
played, even if N is more than the screen size.
Warning: some systems use ^Y as a special job control
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character.
d or ^D Scroll forward N lines, default
one half of the screen size. If N is specified,
it becomes the new default for subsequent
d and u commands.
u or ^U Scroll backward N lines, de-
fault 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.
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. (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.)
m Followed by any lowercase letter, marks the cur-
rent 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 sin-
gle quote, returns to the postion at which the
last "large" movement command was executed. All
marks are lost when a new file is examined.
^X^X Same as single quote.
/pattern Search forward in the file for
the N-th line containing the pattern. N de-
faults to 1. The pattern is a regular expression,
as recognized by ed. The search
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starts at the second line displayed (but see
the -a option, which changes this).
?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.
/!pattern Like /, but the search is for
the N-th line which does NOT contain the pattern.
?!pattern Like ?, but the search is for
the N-th line which does NOT contain the pattern.
n Repeat previous search, for N-th line contain-
ing the last pattern (or NOT containing the
last pattern, if the previous search was /! or
?!).
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. If the filename
is a pound sign (#), the previously examined file
is re-examined.
^X^V or :e Same as E. Warning: some
systems use ^V as a special literalization
character.
N or :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 exam-
ined.
P or :p Examine the previous file. If
a number N is specified, the N-th previous file is
examined.
= or ^G Prints some information about
the file being viewed, including its name and the
line number and byte offset of the bottom line be-
ing 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 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),
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or a string value (such as -P or -t), a new value
may be entered after the option letter.
_ (Underscore.) Followed by one of the command line
option letters (see below), this will print a mes-
sage describing the current setting of that op-
tion. 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 ZZ 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. A percent sign in
the command is replaced by the name of the current
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".
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 com-
mand 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 on the command
line by beginning the command line option with "-+".
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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.
-a Normally, forward searches start just after the
top displayed line (that is, at the second dis-
played line). Thus, forward searches include the
currently displayed screen. The -a option causes
forward searches to start just after the bottom
line displayed, thus skipping the currently dis-
played screen.
-A The -A option causes searches to start at the sec-
ond SCREEN line displayed, as opposed to the de-
fault which is to start at the second REAL line
displayed. For example, suppose a long real line
occupies the first three screen lines. The de-
fault search will start at the second real line
(the fourth screen line), while the -A op-
tion will cause the search to start at the
second screen line (in the midst of the first real
line). (This option is rarely useful.)
-b The -bn option tells less to use a non-standard
number of buffers. Buffers are 1K, and normally
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 Normally, when data is coming from standard input,
buffers are allocated automatically as needed, to
avoid loss of data. The -B option disables this
feature, 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.
-c Normally, less will repaint the screen by
scrolling from the bottom of the screen. If the
-c option is set, when less needs to change
the entire display, it will paint from the top
line down.
-C The -C option is like -c, but the screen is
cleared before it is repainted.
-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 option suppresses this com-
plaint (but does not otherwise change the be-
havior of the program on a dumb terminal).
-e Normally the only way to exit less is via the "q"
command. The -e option tells less to automati-
cally exit the second time it reaches end-of-file.
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-E The -E flag causes less to exit the first time it
reaches end-of-file.
-h Normally, less will scroll backwards when back-
wards movement is necessary. The -h option speci-
fies a maximum number of lines to scroll back-
wards. 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.)
-i The -i option causes searches to ignore case; that
is, uppercase and lowercase are considered identi-
cal. Also, text which is overstruck or underlined
can be searched for.
-l The -l option, followed immediately by a filename,
will cause 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 ordi-
nary file. If the file already exists, less will
ask for confirmation before overwriting it.
-L The -L option is like -l, but it will overwrite an
existing file without asking for confirmation.
If no log file has been specified, the -l and -L
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.
-m Normally, less prompts with a colon. The -m op-
tion causes less to prompt verbosely (like more),
with the percent into the file.
-M The -M option causes less to prompt even more ver-
bosely than more.
-n The -n flag 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 dis-
played in the verbose prompt and in the = command,
and the v command will pass the current line num-
ber to the editor.
-P The -P option provides a way to tailor the
three prompt styles to your own preference. You
would normally put this option in your LESS envi-
ronment variable, rather than type it in with each
less command. Such an option must either be the
last option in the LESS variable, or
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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 special es-
cape sequences. See the section on PROMPTS
for more details.
-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 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 option tells less to be
quiet all the time; that is, never ring the ter-
minal bell. If the terminal has a "visual bell",
it is used instead.
-s The -s option causes consecutive blank lines to be
squeezed into a single blank line. This is use-
ful when viewing nroff output.
-t 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
specified from within less (using the - command)
as a way of examining a new file.
-u If the -u 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 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 dis-
played 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
preceeding character.
-w Normally, less uses a tilde character to represent
lines past the end of the file. The -w option
causes
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blank lines to be used instead.
-x The -xn option sets tab stops every n positions.
The default for n is 8.
-[z] When given a backwards or forwards window command,
less will by default scroll backwards or forwards
one screenful of lines. The -zn option changes the
default scrolling window size to n lines. Note
that the "z" is optional for compatibility
with more.
+ If a command line option begins with +, the re-
mainder of that option is taken to be an ini-
tial 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 spe-
cial case, +<number> acts like +<number>g; that
is, it starts the display at the specified line number
(however, see the caveat under the "g" command
above). If the option starts with ++, the initial
command applies to every file being viewed, not
just the first one. The + command described
previously may also be used to set (or change) an
initial command for every file.
KEY BINDINGS You may define your own less com-
mands by using the program lesskey (1) to create a file
called ".less" in your home directory. This file spec-
ifies a set of command keys and an action asso-
ciated with each key. See the lesskey manual
page for more details.
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 ex-
panded 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 dis-
play is used, an "m" means use the middle
line, a "b" means use the bottom
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line, and a "B" means use the line just after the
bottom line.
%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.
%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 Replaced by the size of the current input file.
%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 in-
stead.
The format of the prompt string can be changed depend-
ing on certain conditions. A question mark followed by
a single character acts like an "IF": depending on
the following character, a condition is evaluated. If
the condition is true, any characters following the
question mark and condition character, up to a period,
are included in the prompt. If the condition is false,
such characters are not included. A colon appearing
between the question mark and the period can be used to
establish an "ELSE": any characters between the colon
and the period are included in the string if and only
if the IF condition is false. Condition 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.
?e True if at end-of-file.
?f True if there is an input filename (that is, if
input is not a pipe).
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?lX True if the line number of the specified line
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 True if the size of current input file is known.
?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) be-
come literally part of the prompt. Any of the special
characters may be included in the prompt literally by
preceeding 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, oth-
erwise 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) ..?ltline %lt :byte %bB?s/%s
..
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?e(END) ?x- Next %x.:?pB%pB..%t
And here is the default message produced by the = com-
mand:
?f%f .?m(file %i of %m) .?ltline %lt .
byte %bB?s/%s. ?e(END) :?pB%pB..%t
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.
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