-Options are also taken from the environment variable "LESS".
-For example,
-to avoid typing "less -options ..." each time
-.I less
-is invoked, you might tell
-.I csh:
-.sp
-setenv LESS "-options"
-.sp
-or if you use
-.I sh:
-.sp
-LESS="-options"; export LESS
-.sp
-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 "-+".
-.sp
-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.
-.IP -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.
-.IP -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.)
-.IP -b
-The -b\fIn\fR option tells
-.I 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 \fIn\fR specifies a different number of buffers to use.
-.IP -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.
-.IP -c
-Normally,
-.I less
-will repaint the screen by scrolling from the bottom of the screen.
-If the -c option is set, when
-.I less
-needs to change the entire display, it will paint from the top line down.
-.IP -C
-The -C option is like -c, but the screen is cleared before it is repainted.
-.IP -d
-Normally,
-.I 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).
-.IP -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.
-.IP -E
-The -E flag causes less to exit the first time it reaches end-of-file.
-.IP -h
-Normally,
-.I 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.)
-.IP -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.
-.IP -l
-The -l option, followed immediately by a filename,
-will cause
-.I 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.
-.IP -L
-The -L option is like -l, but it will overwrite an existing
-file without asking for confirmation.
-.sp
-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.
-.IP -m
-Normally,
-.I less
-prompts with a colon.
-The -m option causes
-.I less
-to prompt verbosely (like
-.I more),
-with the percent into the file.
-.IP -M
-The -M option causes
-.I less
-to prompt even more verbosely than
-.I more.
-.IP -n
-The -n flag suppresses line numbers.
-The default (to use line numbers) may cause
-.I 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.
-.IP -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.
-.IP -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
-.I less
-not to ring the bell at such times.
-If the terminal has a "visual bell", it is used instead.
-.IP -Q
-Even if -q is given,
-.I less
-will ring the bell on certain other errors,
-such as typing an invalid character.
-The -Q option tells
-.I 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.
-.IP -s
-The -s option causes
-consecutive blank lines to be squeezed into a single blank line.
-This is useful when viewing
-.I nroff
-output.
-.IP -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
-.I ctags
-(1) command.
-This option may also be specified from within less
-(using the \- command) as a way of examining a new file.
-.IP -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.
-.IP -U
-If the -U option is given,
-backspaces are printed as the two character sequence "^H".
-.sp
-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.
-.IP -w
-Normally,
-.I less
-uses a tilde character to represent lines past the end of the file.
-The -w option causes blank lines to be used instead.
-.IP -x
-The -x\fIn\fR option sets tab stops every \fIn\fR positions.
-The default for \fIn\fR is 8.
-.IP -[z]
-When given a backwards or forwards window command,
-.I less
-will by
-default scroll backwards or forwards one screenful of lines.
-The -z\fIn\fR option changes the default scrolling window size
-to \fIn\fR lines.
-Note that the "z" is optional for compatibility with
projects / unix-history / blobdiff