less.man

早期freebsd实现

LESS(1)                                                   LESS(1)


              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 man-
       ual 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 environ-
       ment variable may be used to select another character set.
       If it is set to the value "latin1", the ISO 8859/1 charac-
       ter set is assumed.  Latin-1 is the same as ASCII,  except
       characters between 128 and 255 are treated as normal char-
       acters.  The only valid values for  LESSCHARSET  currently
       are "ascii" and "latin1".

       In  special cases, it may be desired to tailor _l_e_s_s to use
       a character set other than the  ones  definable  by  LESS-
       CHARSET.   In  this  case,  the environment variable LESS-
       CHARDEF can be used to define a character set.  It  should
       be set to a string where each character in the string rep-
       resents 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  repeti-
       tion.   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



                                                               13





LESS(1)                                                   LESS(1)


       would be normal.  (This is an example, and does not neces-
       sarily represent any real character set.)

       Setting LESSCHARDEF to "8bcccbcc18b95.b" is  the  same  as
       setting  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 dis-
       played 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  pre-
       ceding  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  ordi-
       nary  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 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 specified 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.




                                                               14





LESS(1)                                                   LESS(1)


       %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  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 instead.

       The  format  of the prompt string can be changed depending
       on certain conditions.  A question mark followed by a sin-
       gle  character acts like an "IF": depending on the follow-
       ing 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.

       ?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.




                                                               15





LESS(1)                                                   LESS(1)


       ?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 file-
       name  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  refer-
       ence,  here are the defaults for the other two prompts (-m
       and -M respectively).  Each is broken into two lines  here



                                                               16





LESS(1)                                                   LESS(1)


       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?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
       purpose:  if  an environment variable LESSEDIT is defined,
       it is used as the command to be executed when the  v  com-
       mand  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.


EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS
       COLUMNS
              Sets  the  number  of columns on the screen.  Takes
              precedence 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).

       LESS   Flags which are passed to _l_e_s_s automatically.

       LESSBINFMT
              Format for  displaying  non-printable,  non-control
              characters.

       LESSCHARDEF
              Defines a character set.

       LESSCHARSET
              Selects a predefined character set.

       LESSEDIT
              Editor  prototype  string (used for the v command).



                                                               17





LESS(1)                                                   LESS(1)


              See discussion under PROMPTS.

       LESSHELP
              Name of the help file.

       LINES  Sets the number of  lines  on  the  screen.   Takes
              precedence  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.


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.

























                                                               18