less - opposite of more

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SYNOPSIS

DESCRIPTION

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 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 final 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 below). 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 displayed, even if N is more than the screen size. Warning: some systems use ^Y as a special job control 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, 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.

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 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 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 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 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 containing 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 examined.

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 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 change the setting of that option and print a message describing the new setting. 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.

_

(Underscore.) Followed by one of the command line option letters (see below), this will print a message 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 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

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 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 "-+".

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 displayed 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 displayed screen.

-A

The -A option causes searches to start at the second SCREEN line displayed, as opposed to the default which is to start at the second REAL line displayed. For example, suppose a long real line occupies the first three screen lines. The default search will start at the second real line (the fourth screen line), while the -A option 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 complaint (but does not otherwise change the behavior 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 automatically exit the second time it reaches end-of-file.

-E

The -E flag causes less to exit the first time it reaches end-of-file.

-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.)

-i

The -i option causes searches to ignore case; that is, uppercase and lowercase are considered identical. 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 ordinary 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 option causes less to prompt verbosely (like more), with the percent into the file.

-M

The -M option causes less to prompt even more verbosely 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 displayed in the verbose prompt and in the = command, and the v command will pass the current line number 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 environment variable, rather than type it 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 special escape 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 terminal 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 useful 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 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 preceeding character.

-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.

-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 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. The + command described previously may also be used to set (or change) an initial command for every file.

KEY BINDINGS

PROMPTS

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, 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 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 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.

?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.

?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) become 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, 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) ..?ltline %lt :byte %bB?s/%s ..
	?e(END) ?x- Next\: %x.:?pB%pB\%..%t

?f%f .?m(file %i of %m) .?ltline %lt .
	byte %bB?s/%s. ?e(END) :?pB%pB\%..%t

SEE ALSO

WARNINGS

Created by unroff & hp-tools. © somebody (See intro for details). All Rights Reserved. Last modified 11/5/97