less.man

早期freebsd实现

LESS(1)                                                   LESS(1)


       --     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  mes-
              sage  describing  the new setting.  (The "--_X" com-
              mand 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 mes-
              sage 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  initially 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
              variable EDITOR, or defaults to "vi".  See also the
              discussion of LESSEDIT under the section on PROMPTS
              below.


       ! 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.   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



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LESS(1)                                                   LESS(1)


              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 environ-
       ment 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.

       -?     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  dis-
              played  on the screen, thus skipping all lines dis-
              played on the screen.  By default,  searches  start
              at the second line 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



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LESS(1)                                                   LESS(1)


              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 otherwise 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 back-
              ward.  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  let-
              ters appear in 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 immedi-
              ately after the target line.  For example, if "-j4"



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LESS(1)                                                   LESS(1)


              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
              specified.   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  begin-
              ning 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 overwriting 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.

              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.




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LESS(1)                                                   LESS(1)


       -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  spe-
              cial  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 charac-
              ter).   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 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



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LESS(1)                                                   LESS(1)


              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 specified 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  capability.   Other
              backspaces are deleted, along  with  the  preceding
              character.   Carriage  returns immediately followed
              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  for-
              ward.   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  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  com-
              patibility with _m_o_r_e_.

       +      If a command line option begins with ++, the remain-
              der of that option is taken to be an  initial  com-
              mand  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



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