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Text File | 1992-01-03 | 40.0 KB | 1,123 lines |
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- NNAAMMEE
- less - opposite of more
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- SSYYNNOOPPSSIISS
- lleessss --??
- lleessss [[--[[++]]aaBBccCCddeeEEffHHiimmMMnnNNqqQQrrssSSuuUUww]]
- [[--bb _b_u_f_s]] [[--hh _l_i_n_e_s]] [[--jj _l_i_n_e]] [[--kk _k_e_y_f_i_l_e]]
- [[--{{ooOO}} _l_o_g_f_i_l_e]] [[--pp _p_a_t_t_e_r_n]] [[--PP _p_r_o_m_p_t]] [[--tt _t_a_g]]
- [[--TT _t_a_g_f_i_l_e]] [[--xx _t_a_b]] [[--yy _l_i_n_e_s]] [[--[[zz]] _l_i_n_e_s]]
- [[++[[++]]_c_m_d]] [[_f_i_l_e_n_a_m_e]]......
-
-
- DDEESSCCRRIIPPTTIIOONN
- _L_e_s_s is a program similar to _m_o_r_e (1), but which allows
- backward movement in the file as well as forward movement.
- Also, _l_e_s_s does not have to read the entire input file
- before starting, so with large input files it starts up fas-
- ter than text editors like _v_i (1). _L_e_s_s uses termcap (or
- terminfo on some systems), so it can run on a variety of
- terminals. There is even limited support for hardcopy ter-
- minals. (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 _m_o_r_e and _v_i. Commands may be pre-
- ceded by a decimal number, called N in the descriptions
- below. The number is used by some commands, as indicated.
-
-
- CCOOMMMMAANNDDSS
- 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 for-
- get 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. Warning: some systems
- use ^V as a special literalization 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 screen size.
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- d or ^D
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- 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 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 _l_e_s_s has already read to the
- end of the file. It is always fast, but not always
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- 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, respec-
- tively. 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, respec-
- tively. For example, "ESC ^B < >" could be used to go
- backward to the < which matches the > in 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" move-
- ment command was executed. Followed by a ^ or $, jumps
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- 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 containing
- the pattern. N defaults to 1. The pattern is a regu-
- lar expression, as recognized by _e_d. 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 begin-
- ning of the pattern; they modify the type of search
- rather than become part of the pattern:
-
- ! Search for lines which do NOT match the pattern.
-
- * Search multiple files. That is, if the search
- reaches the end of the current file without find-
- ing a match, the search continues 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, regardless of what
- is currently displayed on the screen or the set-
- tings of the -a or -j options.
-
- ?pattern
- Search backward in the file for the N-th line contain-
- ing the pattern. The search starts at the line immedi-
- ately before the top line displayed.
-
- Certain characters are special as in the / command:
-
- ! Search for lines which do NOT match the pattern.
-
- * Search multiple files. That is, if the search
- reaches the beginning of the current file without
- finding a match, the search continues in the pre-
- vious file in the command line list.
-
- @ Begin the search at the last line of the last file
- in the command line list, regardless of what is
- currently displayed on the screen or the settings
- of the -a or -j options.
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- ESC-/pattern
- Same as "/*".
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- ESC-?pattern
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- Same as "?*".
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- n Repeat previous search, for N-th line containing the
- last pattern. If the previous search was modified 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 direction.
-
- ESC-n
- Repeat previous search, but crossing file boundaries.
- The effect is as if the previous search were modified
- by *.
-
- ESC-N
- Repeat previous search, but in the reverse direction
- 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 pound sign (#) is replaced
- by the name of the previously examined file. The
- filename is inserted 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 special
- 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.
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- = or ^G or :f
- Prints some information about the file being viewed,
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- 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 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. If no new value is
- entered, a message describing the current setting is
- printed and nothing is changed.
-
- -+ Followed by one of the command line option letters (see
- below), this will reset the option to its default set-
- ting and print a message describing the new setting.
- (The "-+_X" command does the same thing as "-+_X" on the
- command line.) This does not work for string-valued
- options.
-
- -- Followed by one of the command line option letters (see
- below), this will reset the option to the "opposite" of
- 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 work for
- numeric or string-valued options.
-
- _ (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 _l_e_s_s to ini-
- tially display each file starting at the end rather
- than the beginning.
-
- V Prints the version number of _l_e_s_s being run.
-
- q or :q or :Q or ZZ or ESC ESC
- Exits _l_e_s_s.
-
- 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 vari-
- able EDITOR, or defaults to "vi". See also the discus-
- sion of LESSEDIT under the section on PROMPTS below.
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- ! shell-command
- Invokes a shell to run the shell-command given. A per-
- cent 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 first line on the
- current screen and the position marked by the letter.
- <m> may also be ^ or $ to indicate beginning or end of
- file respectively. If <m> is . or newline, the current
- screen is piped.
-
- OOPPTTIIOONNSS
- Command line options are described below. Most options may
- be changed while _l_e_s_s is running, via the "-" command.
-
- Options are also taken from the environment variable "LESS".
- For example, to avoid typing "less -options ..." each time
- _l_e_s_s is invoked, you might tell _c_s_h:
-
- setenv LESS "-options"
-
- or if you use _s_h:
-
- LESS="-options"; export LESS
-
- The environment variable is parsed before the command line,
- so command line options override the LESS environment vari-
- able. 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 _l_e_s_s (the same as the h command). If this option is
- given, all other options are ignored, and _l_e_s_s 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 displayed
- on the screen, thus skipping all lines displayed on the
- screen. By default, searches start at the second line
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- on the screen (or after the last found line; see the -j
- option).
-
- -b_n Causes _l_e_s_s 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 coming from
- standard input, buffers are allocated automatically as
- needed to avoid loss of data.
-
- -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 oth-
- erwise change the behavior of _l_e_s_s on a dumb terminal).
-
- -e Causes _l_e_s_s to automatically exit the second time it
- reaches end-of-file. By default, the only way to exit
- _l_e_s_s is via the "q" command.
-
- -E Causes _l_e_s_s 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, _l_e_s_s will refuse to open non-
- regular files.
-
- -h_n Specifies a maximum number of lines to scroll backward.
- 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 letters appear in
-
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- the search pattern.
-
- -j_n 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
- immediately after the target line. For example, if "-
- j4" is used, the target line is the fourth line on the
- screen, so searches begin at the fifth line on the
- screen.
-
- -k_f_i_l_e_n_a_m_e
- Causes _l_e_s_s to open and interpret the named file as a
- _l_e_s_s_k_e_y (1) file. Multiple -k options may be speci-
- fied. If a file called .less exists in the user's home
- directory, this file is also used as a _l_e_s_s_k_e_y file.
-
- -m Causes _l_e_s_s to prompt verbosely (like _m_o_r_e), with the
- percent into the file. By default, _l_e_s_s prompts with a
- colon.
-
- -M Causes _l_e_s_s to prompt even more verbosely than _m_o_r_e.
-
- -n Suppresses line numbers. The default (to use line
- numbers) may cause _l_e_s_s 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 beginning
- of each line in the display.
-
- -o_f_i_l_e_n_a_m_e
- Causes _l_e_s_s 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, _l_e_s_s will ask for confirmation before overwrit-
- ing it.
-
- -O_f_i_l_e_n_a_m_e
- The -O option is like -o, but it will overwrite an
- existing file without asking for confirmation.
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- If no log file has been specified, the -o and -O
- options can be used from within _l_e_s_s 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 _l_e_s_s.
-
- -p_p_a_t_t_e_r_n
- The -p option on the command line is equivalent to
- specifying +/_p_a_t_t_e_r_n; that is, it tells _l_e_s_s to start
- at the first occurence of _p_a_t_t_e_r_n in the file.
-
- -P_p_r_o_m_p_t
- 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 _l_e_s_s 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 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,
- _l_e_s_s cannot keep track of the actual appearance of the
- screen (since this depends on how the screen responds
- to each type of control character). 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 _n_r_o_f_f
- output.
-
- -S Causes lines longer than the screen width to be chopped
-
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- 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.
-
- -t_t_a_g
- 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 _c_t_a_g_s (1) command.
- This option may also be specified from within _l_e_s_s
- (using the - command) as a way of examining a new file.
- The command ":t" is equivalent to specifying -t from
- within _l_e_s_s.
-
- -T_t_a_g_s_f_i_l_e
- 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 speci-
- fied 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 capa-
- bility. Other backspaces are deleted, along with the
- preceding character. Carriage returns immediately fol-
- lowed 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.
-
- -x_n Sets tab stops every _n positions. The default for _n is
- 8.
-
- -y_n Specifies a maximum number of lines to scroll forward.
- 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
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- 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 compatibility with _m_o_r_e.
-
- + If a command line option begins with ++, the remainder
- of that option is taken to be an initial command to
- _l_e_s_s. For example, +G tells _l_e_s_s 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> 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.
-
-
- KKEEYY BBIINNDDIINNGGSS
- You may define your own _l_e_s_s commands by using the program
- _l_e_s_s_k_e_y (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 _l_e_s_s_k_e_y manual
- page for more details.
-
-
- NNAATTIIOONNAALL CCHHAARRAACCTTEERR SSEETTSS
- 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, _l_e_s_s uses the ASCII character set. In the ASCII
- character set, characters with values between 128 and 255
- are treated as binary. The LESSCHARSET environment variable
- may be used to select another character set. If it is set
- to the value "latin1", the ISO 8859/1 character set is
- assumed. Latin-1 is the same as ASCII, except characters
- between 128 and 255 are treated as normal characters. The
- only valid values for LESSCHARSET currently are "ascii" and
- "latin1".
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- In special cases, it may be desired to tailor _l_e_s_s to use a
- character set other than the ones definable by LESSCHARSET.
- In this case, the environment variable LESSCHARDEF can be
- used to define a character set. It should be set to a
- string where each character in the string represents 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 repetition. 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 to be the same as the
- last, so characters 9 through 255 would be normal. (This is
- an example, and does not necessarily represent any real
- character set.)
-
- Setting LESSCHARDEF to "8bcccbcc18b95.b" is the same as set-
- ting 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 displayed 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 preceding 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.
-
-
- PPRROOMMPPTTSS
- 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 expanded
- according to what the following character is:
-
- %b_X 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
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- 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 speci-
- fied 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.
-
- %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.
-
- %l_X 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.
-
- %p_X 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 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 condi-
- tion 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
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- 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.
-
- ?b_X 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.
-
- ?f True if there is an input filename (that is, if input
- is not a pipe).
-
- ?l_X 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.
-
- ?p_X 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
- 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
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- 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 rea-
- dability 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?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 pur-
- pose: if an environment variable LESSEDIT is defined, it is
- used as the command to be executed when the v command 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.
-
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- EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
- COLUMNS
- Sets the number of columns on the screen. Takes pre-
- cedence 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).
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- LESS Flags which are passed to _l_e_s_s automatically.
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- LESSBINFMT
- Format for displaying non-printable, non-control char-
- acters.
-
- LESSCHARDEF
- Defines a character set.
-
- LESSCHARSET
- Selects a predefined character set.
-
- LESSEDIT
- Editor prototype string (used for the v command). See
- discussion under PROMPTS.
-
- LESSHELP
- Name of the help file.
-
- LINES
- Sets the number of lines on the screen. Takes pre-
- cedence 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 _l_e_s_s is being run.
-
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- SSEEEE AALLSSOO
- lesskey(1)
-
-
- WWAARRNNIINNGGSS
- 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.
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