less(1)



LESS(1)                     General Commands Manual                    LESS(1)

NAME
       less - opposite of more

SYNOPSIS
       less -?
       less --help
       less -V
       less --version
       less [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
            [-b space] [-h lines] [-j line] [-k keyfile]
            [-{oO} logfile] [-p pattern] [-P prompt] [-t tag]
            [-T tagsfile] [-x tab,...] [-y lines] [-[z] lines]
            [-# shift] [+[+]cmd] [--] [filename]...
       (See  the  OPTIONS section for alternate option syntax with long option
       names.)

DESCRIPTION
       Less is a program similar to more (1), but it has many  more  features.
       Less  does  not  have to read the entire input file before starting, so
       with large input files it starts up faster than text  editors  like  vi
       (1).  Less uses termcap (or terminfo on some systems), so it can run on
       a variety of terminals.  There is even  limited  support  for  hardcopy
       terminals.   (On  a hardcopy terminal, lines which should be printed at
       the top of the screen are prefixed with a caret.)

       Commands are based on both more and vi.  Commands may be preceded by  a
       decimal number, called N in the descriptions below.  The number is used
       by some commands, as indicated.

COMMANDS
       In the following descriptions, ^X means control-X.  ESC stands for  the
       ESCAPE  key;  for  example  ESC-v means the two character sequence "ES-
       CAPE", then "v".

       h or H Help: display a summary of these commands.  If  you  forget  all
              the other commands, remember this one.

       SPACE or ^V or f or ^F
              Scroll  forward  N  lines, default one window (see option -z be-
              low).  If N is more than the screen size, only the final screen-
              ful  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.

       ESC-SPACE
              Like  SPACE,  but  scrolls  a full screenful, even if it reaches
              end-of-file in the process.

       ENTER or RETURN or ^N or e or ^E or j or ^J
              Scroll forward N lines, default 1.  The entire N lines are  dis-
              played, even if N is more than the screen size.

       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.

       b or ^B or ESC-v
              Scroll  backward  N lines, default one window (see option -z be-
              low).  If N is more than the screen size, only the final screen-
              ful 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 dis-
              played,  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.

       J      Like j, but continues to scroll beyond the end of the file.

       K or Y Like k, but continues to scroll  beyond  the  beginning  of  the
              file.

       ESC-) or RIGHTARROW
              Scroll  horizontally right N characters, default half the screen
              width (see the -# option).  If a number N is specified,  it  be-
              comes  the default for future RIGHTARROW and LEFTARROW commands.
              While the text is scrolled, it acts  as  though  the  -S  option
              (chop lines) were in effect.

       ESC-( or LEFTARROW
              Scroll  horizontally  left N characters, default half the screen
              width (see the -# option).  If a number N is specified,  it  be-
              comes the default for future RIGHTARROW and LEFTARROW commands.

       ESC-} or ^RIGHTARROW
              Scroll  horizontally  right  to show the end of the longest dis-
              played line.

       ESC-{ or ^LEFTARROW
              Scroll horizontally left back to the first column.

       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.)

       ESC-F  Like  F,  but  as soon as a line is found which matches the last
              search pattern, the terminal bell is rung and forward  scrolling
              stops.

       g or < or ESC-<
              Go to line N in the file, default 1 (beginning of file).  (Warn-
              ing: 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.   (Warn-
              ing:  this  may  be slow if N is large, or if N is not specified
              and standard input, rather than a file, is being read.)

       ESC-G  Same as G, except if no number N is specified and the  input  is
              standard  input,  goes  to  the  last  line  which  is currently
              buffered.

       p or % Go to a position N percent into the file.  N should be between 0
              and 100, and may contain a decimal point.

       P      Go to the line containing byte offset N in the file.

       {      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 brack-
              ets.

       ]      Like }, but applies to square brackets rather than curly  brack-
              ets.

       ESC-^F Followed  by two characters, acts like {, but uses the two char-
              acters as open and close brackets, respectively.   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  char-
              acters  as  open and close brackets, respectively.  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.  Fol-
              lowed by another single quote, returns to the position at  which
              the last "large" movement command was executed.  Followed by a ^
              or $, jumps to the beginning or end of  the  file  respectively.
              Marks  are  preserved when a new file is examined, so the ' com-
              mand 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 pat-
              tern.  N defaults to 1.  The pattern is a regular expression, as
              recognized by the regular expression library  supplied  by  your
              system.   The search starts at the first line displayed (but see
              the -a and -j options, which change this).

              Certain characters are special if entered at  the  beginning  of
              the  pattern;  they modify the type of search rather than become
              part of the pattern:

              ^N or !
                     Search for lines which do NOT match the pattern.

              ^E or *
                     Search multiple files.  That is, if  the  search  reaches
                     the  END of the current file without finding a match, the
                     search continues in the next file  in  the  command  line
                     list.

              ^F or @
                     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 settings of the -a or -j
                     options.

              ^K     Highlight any text which matches the pattern on the  cur-
                     rent screen, but don't move to the first match (KEEP cur-
                     rent position).

              ^R     Don't interpret regular expression  metacharacters;  that
                     is, do a simple textual comparison.

       ?pattern
              Search  backward  in  the  file for the N-th line containing the
              pattern.  The search starts at the last line displayed (but  see
              the -a and -j options, which change this).

              Certain characters are special as in the / command:

              ^N or !
                     Search for lines which do NOT match the pattern.

              ^E or *
                     Search  multiple  files.   That is, if the search reaches
                     the beginning of  the  current  file  without  finding  a
                     match,  the  search continues in the previous file in the
                     command line list.

              ^F or @
                     Begin the search at the last line of the last file in the
                     command  line  list, regardless of what is currently dis-
                     played on the screen or the settings of the -a or -j  op-
                     tions.

              ^K     As in forward searches.

              ^R     As in forward searches.

       ESC-/pattern
              Same as "/*".

       ESC-?pattern
              Same as "?*".

       n      Repeat  previous  search, for N-th line containing the last pat-
              tern.  If the previous search was modified by ^N, the search  is
              made  for the N-th line NOT containing the pattern.  If the pre-
              vious search was modified by ^E, the  search  continues  in  the
              next  (or  previous)  file if not satisfied in the current file.
              If the previous search was modified by ^R, the  search  is  done
              without  using  regular  expressions.  There is no effect if the
              previous search was modified by ^F or ^K.

       N      Repeat previous search, but in the reverse direction.

       ESC-n  Repeat previous search, but crossing file boundaries.   The  ef-
              fect is as if the previous search were modified by *.

       ESC-N  Repeat  previous search, but in the reverse direction and cross-
              ing file boundaries.

       ESC-u  Undo search highlighting.   Turn  off  highlighting  of  strings
              matching the current search pattern.  If highlighting is already
              off because of a previous ESC-u command, turn highlighting  back
              on.   Any  search  command  will also turn highlighting back on.
              (Highlighting can also be disabled by toggling the -G option; in
              that case search commands do not turn highlighting back on.)

       &pattern
              Display  only  lines which match the pattern; lines which do not
              match the pattern are not displayed.  If pattern  is  empty  (if
              you  type  &  immediately  followed  by ENTER), any filtering is
              turned off, and all lines are displayed.  While filtering is  in
              effect,  an  ampersand  is  displayed  at  the  beginning of the
              prompt, as a reminder that some lines in the file may be hidden.

              Certain characters are special as in the / command:

              ^N or !
                     Display only lines which do NOT match the pattern.

              ^R     Don't interpret regular expression  metacharacters;  that
                     is, do a simple textual comparison.

       :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.  However, two consecutive percent  signs  are  simply  re-
              placed  with  a single percent sign.  This allows you to enter a
              filename that contains a percent sign in the  name.   Similarly,
              two  consecutive  pound  signs  are replaced with a single pound
              sign.  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.  If the
              filename contains one or more spaces, the entire filename should
              be enclosed in double quotes (also see the -" option).

       ^X^V or E
              Same  as :e.  Warning: some systems use ^V as a special literal-
              ization character.  On such systems, you may not be able to  use
              ^V.

       :n     Examine  the next file (from the list of files given in the com-
              mand 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.

       :d     Remove the current file from the list of files.

       t      Go  to the next tag, if there were more than one matches for the
              current tag.  See the -t option for more details about tags.

       T      Go to the previous tag, if there were more than one matches  for
              the current tag.

       = or ^G or :f
              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, 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 OPTIONS
              below), this will change the setting of that option and print  a
              message  describing the new setting.  If a ^P (CONTROL-P) is en-
              tered immediately after the dash, the setting of the  option  is
              changed  but  no message is printed.  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  set-
              ting is printed and nothing is changed.

       --     Like  the  -  command, but takes a long option name (see OPTIONS
              below) rather than a single option letter.  You must press ENTER
              or  RETURN after typing the option name.  A ^P immediately after
              the second dash suppresses printing of a message describing  the
              new setting, as in the - command.

       -+     Followed by one of the command line option letters this will re-
              set the option to its default setting and print  a  message  de-
              scribing  the  new  setting.   (The  "-+X" command does the same
              thing as "-+X" on the command line.)  This  does  not  work  for
              string-valued options.

       --+    Like  the -+ command, but takes a long option name rather than a
              single option letter.

       -!     Followed by one of the command line option  letters,  this  will
              reset  the  option  to the "opposite" of its default setting and
              print a message describing the new setting.  This does not  work
              for numeric or string-valued options.

       --!    Like  the -! command, but takes a long option name rather than a
              single option letter.

       _      (Underscore.)  Followed by one of the command line  option  let-
              ters,  this  will print a message describing the current setting
              of that option.  The setting of the option is not changed.

       __     (Double underscore.)  Like the _ (underscore) command, but takes
              a long option name rather than a single option letter.  You must
              press ENTER or RETURN after typing the option name.

       +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 :q or :Q or ZZ
              Exits less.

       The following four 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 VISUAL if defined,
              or  EDITOR if VISUAL is not defined, or defaults to "vi" if nei-
              ther VISUAL nor EDITOR is defined.  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 exam-
              ined file.  "!!" repeats the last shell command.   "!"  with  no
              shell  command  simply  invokes  a  shell.  On Unix systems, the
              shell is taken from the environment variable SHELL, or  defaults
              to  "sh".   On  MS-DOS and OS/2 systems, the shell is the normal
              command processor.

       | <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 indi-
              cate beginning or end of file respectively.  If <m> is . or new-
              line, the current screen is piped.

       s filename
              Save  the  input  to  a file.  This only works if the input is a
              pipe, not an ordinary file.

OPTIONS
       Command line options are described below.  Most options may be  changed
       while less is running, via the "-" command.

       Most  options  may be given in one of two forms: either a dash followed
       by a single letter, or two dashes followed by a long  option  name.   A
       long  option name may be abbreviated as long as the abbreviation is un-
       ambiguous.  For example, --quit-at-eof may be abbreviated  --quit,  but
       not --qui, since both --quit-at-eof and --quiet begin with --qui.  Some
       long option names are in uppercase, such as --QUIT-AT-EOF, as  distinct
       from  --quit-at-eof.  Such option names need only have their first let-
       ter capitalized; the remainder of the name may be in either case.   For
       example, --Quit-at-eof is equivalent to --QUIT-AT-EOF.

       Options are also taken from the environment variable "LESS".  For exam-
       ple, 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

       On  MS-DOS,  you don't need the quotes, but you should replace any per-
       cent signs in the options string by double percent signs.

       The environment variable is parsed before the command line, so  command
       line  options override the LESS environment variable.  If an option ap-
       pears in the LESS variable, it can be reset to its default value on the
       command line by beginning the command line option with "-+".

       Some  options  like -k or -D require a string to follow the option let-
       ter.  The string for that option is considered to  end  when  a  dollar
       sign  ($)  is found.  For example, you can set two -D options on MS-DOS
       like this:

       LESS="Dn9.1$Ds4.1"

       If the --use-backslash option appears earlier in the  options,  then  a
       dollar  sign or backslash may be included literally in an option string
       by preceding it with a backslash.  If the --use-backslash option is not
       in  effect, then backslashes are not treated specially, and there is no
       way to include a dollar sign in the option string.

       -? or --help
              This option displays a summary of the commands accepted by  less
              (the  same  as the h command).  (Depending on how your shell in-
              terprets the question mark, it may be  necessary  to  quote  the
              question mark, thus: "-\?".)

       -a or --search-skip-screen
              By  default,  forward searches start at the top of the displayed
              screen and backwards searches start at the bottom  of  the  dis-
              played  screen (except for repeated searches invoked by the n or
              N commands, which start after or before the  "target"  line  re-
              spectively;  see  the -j option for more about the target line).
              The -a option causes forward searches to instead  start  at  the
              bottom  of  the screen and backward searches to start at the top
              of the screen, thus skipping all lines displayed on the screen.

       -A or --SEARCH-SKIP-SCREEN
              Causes all forward searches (not just non-repeated searches)  to
              start  just  after the target line, and all backward searches to
              start just before the target line.  Thus, forward searches  will
              skip part of the displayed screen (from the first line up to and
              including the target line).  Similarly backwards  searches  will
              skip the displayed screen from the last line up to and including
              the target line.  This was the default behavior in less versions
              prior to 441.

       -bn or --buffers=n
              Specifies  the  amount  of  buffer  space less will use for each
              file, in units of kilobytes (1024 bytes).  By  default  64 K  of
              buffer  space  is used for each file (unless the file is a pipe;
              see the -B option).  The -b  option  specifies  instead  that  n
              kilobytes of buffer space should be used for each file.  If n is
              -1, buffer space is unlimited; that is, the entire file  can  be
              read into memory.

       -B or --auto-buffers
              By default, when data is read from a pipe, buffers are allocated
              automatically as needed.  If a large amount of data is read from
              the  pipe,  this  can cause a large amount of memory to be allo-
              cated.  The -B option disables this automatic allocation of buf-
              fers for pipes, so that only 64 K (or the amount of space speci-
              fied by the -b option) is used for the pipe.  Warning: use of -B
              can  result  in  erroneous display, since only the most recently
              viewed part of the piped data is kept  in  memory;  any  earlier
              data is lost.

       -c or --clear-screen
              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 or --CLEAR-SCREEN
              Same as -c, for compatibility with older versions of less.

       -d or --dumb
              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  less  on  a
              dumb terminal.

       -Dxcolor or --color=xcolor
              [MS-DOS only] Sets the color of the text displayed.  x is a sin-
              gle character which selects the type of text whose color is  be-
              ing  set:  n=normal,  s=standout, d=bold, u=underlined, k=blink.
              color is a pair of numbers separated by  a  period.   The  first
              number  selects  the foreground color and the second selects the
              background color of the text.  A single number N is the same  as
              N.M, where M is the normal background color.  x may also be a to
              toggle strict ANSI sequence rendering (SGR mode).

       -e or --quit-at-eof
              Causes less to automatically exit the  second  time  it  reaches
              end-of-file.   By  default, the only way to exit less is via the
              "q" command.

       -E or --QUIT-AT-EOF
              Causes less to automatically exit the first time it reaches end-
              of-file.

       -f or --force
              Forces non-regular files to be opened.  (A non-regular file is a
              directory or a device special file.)  Also suppresses the  warn-
              ing message when a binary file is opened.  By default, less will
              refuse to open non-regular files.  Note that some operating sys-
              tems will not allow directories to be read, even if -f is set.

       -F or --quit-if-one-screen
              Causes less to automatically exit if the entire file can be dis-
              played on the first screen.

       -g or --hilite-search
              Normally, less will highlight ALL strings which match  the  last
              search  command.   The  -g option changes this behavior to high-
              light only the particular string which was  found  by  the  last
              search command.  This can cause less to run somewhat faster than
              the default.

       -G or --HILITE-SEARCH
              The -G option suppresses all highlighting of  strings  found  by
              search commands.

       -hn or --max-back-scroll=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 or --ignore-case
              Causes searches to ignore case; that is, uppercase and lowercase
              are  considered identical.  This option is ignored if any upper-
              case letters appear in the search pattern; in other words, if  a
              pattern  contains  uppercase  letters, then that search does not
              ignore case.

       -I or --IGNORE-CASE
              Like -i, but searches ignore case even if the  pattern  contains
              uppercase letters.

       -jn or --jump-target=n
              Specifies  a line on the screen where the "target" line is to be
              positioned.  The target line is the line specified by  any  com-
              mand  to  search for a pattern, jump to a line number, jump to a
              file percentage or jump to a tag.  The screen line may be speci-
              fied  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 rel-
              ative to the bottom of the screen: the bottom line on the screen
              is -1, the second to the bottom is -2, and so on.   Alternately,
              the  screen line may be specified as a fraction of the height of
              the screen, starting with a decimal point: .5 is in  the  middle
              of  the screen, .3 is three tenths down from the first line, and
              so on.  If the line is specified as a fraction, the actual  line
              number  is  recalculated  if  the terminal window is resized, so
              that the target line remains at the specified  fraction  of  the
              screen  height.   If any form of the -j option is used, repeated
              forward searches (invoked with "n" or "N") begin at the line im-
              mediately  after the target line, and repeated backward searches
              begin at the target line, unless changed by -a or -A.  For exam-
              ple, if "-j4" is used, the target line is the fourth line on the
              screen, so forward searches begin  at  the  fifth  line  on  the
              screen.   However nonrepeated searches (invoked with "/" or "?")
              always begin at the start or end of the current  screen  respec-
              tively.

       -J or --status-column
              Displays  a  status  column at the left edge of the screen.  The
              status column shows the lines that matched the  current  search.
              The  status column is also used if the -w or -W option is in ef-
              fect.

       -kfilename or --lesskey-file=filename
              Causes less to open and interpret the named file  as  a  lesskey
              (1) file.  Multiple -k options may be specified.  If the LESSKEY
              or LESSKEY_SYSTEM environment variable is set, or if  a  lesskey
              file is found in a standard place (see KEY BINDINGS), it is also
              used as a lesskey file.

       -K or --quit-on-intr
              Causes less to exit immediately (with status 2) when  an  inter-
              rupt  character  (usually  ^C) is typed.  Normally, an interrupt
              character causes less to stop whatever it is doing and return to
              its  command  prompt.  Note that use of this option makes it im-
              possible to return to the command prompt from the "F" command.

       -L or --no-lessopen
              Ignore the LESSOPEN environment variable  (see  the  INPUT  PRE-
              PROCESSOR  section  below).   This option can be set from within
              less, but it will apply only to files opened  subsequently,  not
              to the file which is currently open.

       -m or --long-prompt
              Causes  less  to  prompt verbosely (like more), with the percent
              into the file.  By default, less prompts with a colon.

       -M or --LONG-PROMPT
              Causes less to prompt even more verbosely than more.

       -n or --line-numbers
              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 op-
              tion  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  be-
              low).

       -N or --LINE-NUMBERS
              Causes  a  line  number to be displayed at the beginning of each
              line in the display.

       -ofilename or --log-file=filename
              Causes 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.

       -Ofilename or --LOG-FILE=filename
              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  less  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 less.

       -ppattern or --pattern=pattern
              The  -p  option  on the command line is equivalent to specifying
              +/pattern; that is, it tells less to start at the  first  occur-
              rence of pattern in the file.

       -Pprompt or --prompt=prompt
              Provides  a  way  to  tailor the three prompt styles to your own
              preference.  This option would normally be put in the LESS envi-
              ronment variable, rather than being typed in with each less com-
              mand.  Such an option must either be the last option in the LESS
              variable, or be terminated by a dollar sign.
               -Ps  followed by a string changes the default (short) prompt to
              that string.
               -Pm changes the medium (-m) prompt.
               -PM changes the long (-M) prompt.
               -Ph changes the prompt for the help screen.
               -P= changes the message printed by the = command.
               -Pw changes the message printed while waiting for data (in  the
              F command).  All prompt strings consist of a sequence of letters
              and special escape sequences.  See the section  on  PROMPTS  for
              more details.

       -q or --quiet or --silent
              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 or --QUIET or --SILENT
              Causes totally "quiet" operation: the  terminal  bell  is  never
              rung.

       -r or --raw-control-chars
              Causes "raw" control characters to be displayed.  The default is
              to display control characters using the caret notation; for  ex-
              ample,  a  control-A (octal 001) is displayed as "^A".  Warning:
              when the -r option is used, less 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 dis-
              play  problems may result, such as long lines being split in the
              wrong place.

       -R or --RAW-CONTROL-CHARS
              Like -r, but only ANSI "color" escape sequences  are  output  in
              "raw" form.  Unlike -r, the screen appearance is maintained cor-
              rectly in most cases.  ANSI "color"  escape  sequences  are  se-
              quences of the form:

                   ESC [ ... m

              where  the  "..." is zero or more color specification characters
              For the purpose of keeping  track  of  screen  appearance,  ANSI
              color  escape sequences are assumed to not move the cursor.  You
              can make less think that characters other than "m" can end  ANSI
              color  escape  sequences  by  setting  the  environment variable
              LESSANSIENDCHARS to the list of characters which can end a color
              escape  sequence.   And  you can make less think that characters
              other than the standard ones may appear between the ESC and  the
              m  by  setting  the environment variable LESSANSIMIDCHARS to the
              list of characters which can appear.

       -s or --squeeze-blank-lines
              Causes consecutive blank lines to  be  squeezed  into  a  single
              blank line.  This is useful when viewing nroff output.

       -S or --chop-long-lines
              Causes  lines  longer than the screen width to be chopped (trun-
              cated) rather than wrapped.  That is, the portion of a long line
              that does not fit in the screen width is not shown.  The default
              is to wrap long lines; that is, display  the  remainder  on  the
              next line.

       -ttag or --tag=tag
              The -t option, followed immediately by a TAG, will edit the file
              containing that tag.  For this to work, tag information must  be
              available;  for  example, there may be a file in the current di-
              rectory called "tags", which was previously built by  ctags  (1)
              or an equivalent command.  If the environment variable LESSGLOB-
              ALTAGS is set, it is taken to be the name of a command  compati-
              ble  with  global  (1), and that command is executed to find the
              tag.  (See http://www.gnu.org/software/global/global.html).  The
              -t  option  may  also be specified from within less (using the -
              command) as a way of examining a new file.  The command ":t"  is
              equivalent to specifying -t from within less.

       -Ttagsfile or --tag-file=tagsfile
              Specifies a tags file to be used instead of "tags".

       -u or --underline-special
              Causes  backspaces  and carriage returns to be treated as print-
              able characters; that is, they are sent  to  the  terminal  when
              they appear in the input.

       -U or --UNDERLINE-SPECIAL
              Causes  backspaces,  tabs  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 ap-
              pear 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  capabil-
              ity.   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.  Text which is overstruck or  underlined  can  be
              searched for if neither -u nor -U is in effect.

       -V or --version
              Displays the version number of less.

       -w or --hilite-unread
              Temporarily  highlights  the  first  "new"  line after a forward
              movement of a full page.  The first "new" line is the line imme-
              diately  following  the  line  previously  at  the bottom of the
              screen.  Also highlights the target line after a g or p command.
              The  highlight is removed at the next command which causes move-
              ment.  The entire line is highlighted, unless the -J  option  is
              in effect, in which case only the status column is highlighted.

       -W or --HILITE-UNREAD
              Like -w, but temporarily highlights the first new line after any
              forward movement command larger than one line.

       -xn,... or --tabs=n,...
              Sets tab stops.  If only one n is specified, tab stops  are  set
              at  multiples  of n.  If multiple values separated by commas are
              specified, tab stops are set at those positions, and  then  con-
              tinue  with  the  same  spacing  as  the last two.  For example,
              -x9,17 will set tabs at positions 9, 17, 25, 33, etc.   The  de-
              fault for n is 8.

       -X or --no-init
              Disables sending the termcap initialization and deinitialization
              strings to the terminal.  This is  sometimes  desirable  if  the
              deinitialization  string does something unnecessary, like clear-
              ing the screen.

       -yn or --max-forw-scroll=n
              Specifies a maximum number of lines to scroll forward.  If it is
              necessary to scroll forward more than n lines, the screen is re-
              painted 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 or --window=n
              Changes the default scrolling window size to n lines.   The  de-
              fault  is  one screenful.  The z and w commands can also be used
              to change the window size.  The "z" may be omitted for  compati-
              bility with some versions of more.  If the number n is negative,
              it indicates n lines less than the current screen size.  For ex-
              ample, if the screen is 24 lines, -z-4 sets the scrolling window
              to 20 lines.   If  the  screen  is  resized  to  40  lines,  the
              scrolling window automatically changes to 36 lines.

       -"cc or --quotes=cc
              Changes  the  filename quoting character.  This may be necessary
              if you are trying to name a file which contains both spaces  and
              quote  characters.  Followed by a single character, this changes
              the quote character to that character.  Filenames  containing  a
              space should then be surrounded by that character rather than by
              double quotes.  Followed by two  characters,  changes  the  open
              quote  to the first character, and the close quote to the second
              character.  Filenames containing a space should then be preceded
              by  the  open  quote  character  and followed by the close quote
              character.  Note  that  even  after  the  quote  characters  are
              changed,  this  option  remains  -" (a dash followed by a double
              quote).

       -~ or --tilde
              Normally lines after end of file are displayed as a single tilde
              (~).  This option causes lines after end of file to be displayed
              as blank lines.

       -# or --shift
              Specifies the default number of positions to scroll horizontally
              in  the RIGHTARROW and LEFTARROW commands.  If the number speci-
              fied is zero, it sets the default number  of  positions  to  one
              half of the screen width.  Alternately, the number may be speci-
              fied as a fraction of the width of the screen, starting  with  a
              decimal  point:  .5  is  half  of  the screen width, .3 is three
              tenths of the screen width, and so on.  If the number is  speci-
              fied as a fraction, the actual number of scroll positions is re-
              calculated if the terminal window is resized, so that the actual
              scroll remains at the specified fraction of the screen width.

       --follow-name
              Normally, if the input file is renamed while an F command is ex-
              ecuting, less will continue to display the contents of the orig-
              inal  file  despite its name change.  If --follow-name is speci-
              fied, during an F command less will periodically attempt to  re-
              open the file by name.  If the reopen succeeds and the file is a
              different file from the original (which means that  a  new  file
              has  been  created  with  the same name as the original (now re-
              named) file), less will display the contents of that new file.

       --no-keypad
              Disables sending the keypad initialization and  deinitialization
              strings to the terminal.  This is sometimes useful if the keypad
              strings make the numeric keypad behave in an undesirable manner.

       --use-backslash
              This option changes the interpretations of options which  follow
              this one.  After the --use-backslash option, any backslash in an
              option string is removed and the following  character  is  taken
              literally.   This  allows a dollar sign to be included in option
              strings.

       --     A command line argument of "--" marks the end  of  option  argu-
              ments.   Any  arguments  following this are interpreted as file-
              names.  This can be useful when viewing a file whose name begins
              with a "-" or "+".

       +      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  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 ev-
              ery  file  being  viewed, not just the first one.  The + command
              described previously may also be used to set (or change) an ini-
              tial command for every file.

LINE EDITING
       When  entering command line at the bottom of the screen (for example, a
       filename for the :e command, or the pattern for a search command), cer-
       tain  keys  can  be used to manipulate the command line.  Most commands
       have an alternate form in [ brackets ] which can be used if a key  does
       not  exist  on  a  particular keyboard.  (Note that the forms beginning
       with ESC do not work in some MS-DOS and Windows systems because ESC  is
       the  line  erase  character.)  Any of these special keys may be entered
       literally by preceding it with the "literal" character,  either  ^V  or
       ^A.   A  backslash itself may also be entered literally by entering two
       backslashes.

       LEFTARROW [ ESC-h ]
              Move the cursor one space to the left.

       RIGHTARROW [ ESC-l ]
              Move the cursor one space to the right.

       ^LEFTARROW [ ESC-b or ESC-LEFTARROW ]
              (That is, CONTROL and LEFTARROW simultaneously.)  Move the  cur-
              sor one word to the left.

       ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ]
              (That is, CONTROL and RIGHTARROW simultaneously.)  Move the cur-
              sor one word to the right.

       HOME [ ESC-0 ]
              Move the cursor to the beginning of the line.

       END [ ESC-$ ]
              Move the cursor to the end of the line.

       BACKSPACE
              Delete the character to the left of the cursor,  or  cancel  the
              command if the command line is empty.

       DELETE or [ ESC-x ]
              Delete the character under the cursor.

       ^BACKSPACE [ ESC-BACKSPACE ]
              (That  is,  CONTROL  and  BACKSPACE simultaneously.)  Delete the
              word to the left of the cursor.

       ^DELETE [ ESC-X or ESC-DELETE ]
              (That is, CONTROL and DELETE simultaneously.)  Delete  the  word
              under the cursor.

       UPARROW [ ESC-k ]
              Retrieve  the  previous  command  line.  If you first enter some
              text and then press UPARROW, it will retrieve the previous  com-
              mand which begins with that text.

       DOWNARROW [ ESC-j ]
              Retrieve  the  next  command line.  If you first enter some text
              and then press DOWNARROW, it  will  retrieve  the  next  command
              which begins with that text.

       TAB    Complete  the partial filename to the left of the cursor.  If it
              matches more than one filename, the first match is entered  into
              the  command  line.   Repeated  TABs  will  cycle thru the other
              matching filenames.  If the completed filename is a directory, a
              "/"  is  appended to the filename.  (On MS-DOS systems, a "\" is
              appended.)  The environment variable LESSSEPARATOR can  be  used
              to specify a different character to append to a directory name.

       BACKTAB [ ESC-TAB ]
              Like, TAB, but cycles in the reverse direction thru the matching
              filenames.

       ^L     Complete the partial filename to the left of the cursor.  If  it
              matches more than one filename, all matches are entered into the
              command line (if they fit).

       ^U (Unix and OS/2) or ESC (MS-DOS)
              Delete the entire command line, or cancel  the  command  if  the
              command line is empty.  If you have changed your line-kill char-
              acter in Unix to something other than ^U, that character is used
              instead of ^U.

       ^G     Delete the entire command line and return to the main prompt.

KEY BINDINGS
       You  may define your own less commands by using the program lesskey (1)
       to create a lesskey file.  This file specifies a set  of  command  keys
       and  an  action  associated with each key.  You may also use lesskey to
       change the line-editing keys (see LINE EDITING), and to set environment
       variables.   If the environment variable LESSKEY is set, less uses that
       as the name of the lesskey file.  Otherwise, less looks in  a  standard
       place  for  the lesskey file: On Unix systems, less looks for a lesskey
       file called "$HOME/.less".  On MS-DOS and Windows systems,  less  looks
       for  a lesskey file called "$HOME/_less", and if it is not found there,
       then looks for a lesskey file called "_less" in any directory specified
       in  the  PATH  environment variable.  On OS/2 systems, less looks for a
       lesskey file called "$HOME/less.ini", and if  it  is  not  found,  then
       looks  for  a lesskey file called "less.ini" in any directory specified
       in the INIT environment variable, and if it not found there, then looks
       for  a lesskey file called "less.ini" in any directory specified in the
       PATH environment variable.  See the lesskey manual page  for  more  de-
       tails.

       A  system-wide lesskey file may also be set up to provide key bindings.
       If a key is defined in both a local lesskey file and in the system-wide
       file,  key bindings in the local file take precedence over those in the
       system-wide file.  If the environment variable LESSKEY_SYSTEM  is  set,
       less uses that as the name of the system-wide lesskey file.  Otherwise,
       less looks in a standard place for the  system-wide  lesskey  file:  On
       Unix  systems,  the system-wide lesskey file is /usr/local/etc/sysless.
       (However, if less was built with a  different  sysconf  directory  than
       /usr/local/etc, that directory is where the sysless file is found.)  On
       MS-DOS and Windows systems, the system-wide lesskey  file  is  c:\_sys-
       less.  On OS/2 systems, the system-wide lesskey file is c:\sysless.ini.

INPUT PREPROCESSOR
       You  may  define an "input preprocessor" for less.  Before less opens a
       file, it first gives your input preprocessor a chance to modify the way
       the  contents of the file are displayed.  An input preprocessor is sim-
       ply an executable program (or shell script), which writes the  contents
       of the file to a different file, called the replacement file.  The con-
       tents of the replacement file are then displayed in place of  the  con-
       tents  of the original file.  However, it will appear to the user as if
       the original file is opened; that is, less will  display  the  original
       filename as the name of the current file.

       An  input preprocessor receives one command line argument, the original
       filename, as entered by the user.  It  should  create  the  replacement
       file,  and when finished, print the name of the replacement file to its
       standard output.  If the input preprocessor does not output a  replace-
       ment  filename, less uses the original file, as normal.  The input pre-
       processor is not called when viewing standard input.  To set up an  in-
       put  preprocessor,  set  the LESSOPEN environment variable to a command
       line which will invoke your  input  preprocessor.   This  command  line
       should  include  one  occurrence  of the string "%s", which will be re-
       placed by the filename when the input preprocessor command is invoked.

       When less closes a file opened in such a way, it will call another pro-
       gram,  called  the  input  postprocessor, which may perform any desired
       clean-up action (such as  deleting  the  replacement  file  created  by
       LESSOPEN).  This program receives two command line arguments, the orig-
       inal filename as entered by the user, and the name of  the  replacement
       file.   To set up an input postprocessor, set the LESSCLOSE environment
       variable to a command line which will invoke your input  postprocessor.
       It  may  include  two  occurrences of the string "%s"; the first is re-
       placed with the original name of the file and the second with the  name
       of the replacement file, which was output by LESSOPEN.

       For  example, on many Unix systems, these two scripts will allow you to
       keep files in compressed format, but still let less view them directly:

       lessopen.sh:
            #! /bin/sh
            case "$1" in
            *.Z) uncompress -c $1  >/tmp/less.$$  2>/dev/null
                 if [ -s /tmp/less.$$ ]; then
                      echo /tmp/less.$$
                 else
                      rm -f /tmp/less.$$
                 fi
                 ;;
            esac

       lessclose.sh:
            #! /bin/sh
            rm $2

       To use these scripts, put them both where they can be executed and  set
       LESSOPEN="lessopen.sh %s",  and  LESSCLOSE="lessclose.sh %s %s".   More
       complex LESSOPEN and LESSCLOSE scripts may be written to  accept  other
       types of compressed files, and so on.

       It  is  also  possible to set up an input preprocessor to pipe the file
       data directly to less, rather than putting the data into a  replacement
       file.  This avoids the need to decompress the entire file before start-
       ing to view it.  An input preprocessor that works this way is called an
       input  pipe.   An input pipe, instead of writing the name of a replace-
       ment file on its standard output, writes the entire contents of the re-
       placement  file  on  its  standard  output.  If the input pipe does not
       write any characters on its standard output, then there is no  replace-
       ment  file and less uses the original file, as normal.  To use an input
       pipe, make the first character in the LESSOPEN environment  variable  a
       vertical  bar  (|)  to  signify that the input preprocessor is an input
       pipe.

       For example, on many Unix systems, this script will work like the  pre-
       vious example scripts:

       lesspipe.sh:
            #! /bin/sh
            case "$1" in
            *.Z) uncompress -c $1  2>/dev/null
            *)   exit 1
                 ;;
            esac
            exit $?

       To  use  this  script,  put  it  where  it  can  be  executed  and  set
       LESSOPEN="|lesspipe.sh %s".

       Note that a preprocessor cannot output an empty file, since that is in-
       terpreted  as meaning there is no replacement, and the original file is
       used.  To avoid this, if LESSOPEN starts with two  vertical  bars,  the
       exit  status  of  the script becomes meaningful.  If the exit status is
       zero, the output is considered to  be  replacement  text,  even  if  it
       empty.   If  the  exit status is nonzero, any output is ignored and the
       original file is used.  For compatibility  with  previous  versions  of
       less, if LESSOPEN starts with only one vertical bar, the exit status of
       the preprocessor is ignored.

       When an input pipe is used, a LESSCLOSE postprocessor can be used,  but
       it is usually not necessary since there is no replacement file to clean
       up.  In this case, the replacement file name passed  to  the  LESSCLOSE
       postprocessor is "-".

       For  compatibility with previous versions of less, the input preproces-
       sor or pipe is not used if less is viewing standard input.  However, if
       the  first  character of LESSOPEN is a dash (-), the input preprocessor
       is used on standard input as well as other files.  In  this  case,  the
       dash  is  not  considered  to  be part of the preprocessor command.  If
       standard input is being viewed, the input preprocessor is passed a file
       name  consisting of a single dash.  Similarly, if the first two charac-
       ters of LESSOPEN are vertical bar and dash (|-) or  two  vertical  bars
       and  a  dash (||-), the input pipe is used on standard input as well as
       other files.  Again, in this case the dash is not considered to be part
       of the input pipe command.

NATIONAL CHARACTER SETS
       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
              should not be displayed directly and  are  not  expected  to  be
              found in text files.

       A "character set" is simply a description of which characters are to be
       considered normal, control, and binary.   The  LESSCHARSET  environment
       variable  may  be  used to select a character set.  Possible values for
       LESSCHARSET are:

       ascii  BS, TAB, NL, CR, and formfeed are control characters, all  chars
              with  values  between  32 and 126 are normal, and all others are
              binary.

       iso8859
              Selects an ISO 8859 character set.  This is the same  as  ASCII,
              except  characters  between  160  and  255 are treated as normal
              characters.

       latin1 Same as iso8859.

       latin9 Same as iso8859.

       dos    Selects a character set appropriate for MS-DOS.

       ebcdic Selects an EBCDIC character set.

       IBM-1047
              Selects an EBCDIC character set used by  OS/390  Unix  Services.
              This  is the EBCDIC analogue of latin1.  You get similar results
              by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your
              environment.

       koi8-r Selects a Russian character set.

       next   Selects a character set appropriate for NeXT computers.

       utf-8  Selects  the  UTF-8  encoding  of  the  ISO 10646 character set.
              UTF-8 is special in that it supports  multi-byte  characters  in
              the  input  file.   It  is  the only character set that supports
              multi-byte characters.

       windows
              Selects a character set appropriate for  Microsoft  Windows  (cp
              1251).

       In  rare cases, it may be desired to tailor less to use a character set
       other than the ones definable by LESSCHARSET.  In this case, the  envi-
       ronment 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  num-
       ber  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  bi-
       nary,  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 char-
       acter set.)

       This table shows the value of LESSCHARDEF which is equivalent  to  each
       of the possible values for LESSCHARSET:

            ascii     8bcccbcc18b95.b
            dos       8bcccbcc12bc5b95.b.
            ebcdic    5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
                      9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
            IBM-1047  4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
                      191.b
            iso8859   8bcccbcc18b95.33b.
            koi8-r    8bcccbcc18b95.b128.
            latin1    8bcccbcc18b95.33b.
            next      8bcccbcc18b95.bb125.bb

       If  neither  LESSCHARSET nor LESSCHARDEF is set, but any of the strings
       "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_CTYPE  or
       LANG environment variables, then the default character set is utf-8.

       If that string is not found, but your system supports the setlocale in-
       terface, less will use setlocale to determine the character set.   set-
       locale  is controlled by setting the LANG or LC_CTYPE environment vari-
       ables.

       Finally, if the setlocale interface is also not available, the  default
       character set is latin1.

       Control  and  binary  characters  are  displayed  in  standout (reverse
       video).  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 char-
       acter  is displayed as a hex number in angle brackets.  This format can
       be changed by setting the LESSBINFMT environment variable.   LESSBINFMT
       may begin with a "*" and one character to select the display attribute:
       "*k" is blinking, "*d" is bold, "*u" is underlined, "*s"  is  standout,
       and  "*n"  is  normal.  If LESSBINFMT does not begin with a "*", normal
       attribute is assumed.  The remainder of LESSBINFMT is  a  string  which
       may  include one printf-style escape sequence (a % followed by x, X, o,
       d, etc.).  For example, if LESSBINFMT is  "*u[%x]",  binary  characters
       are  displayed  in  underlined hexadecimal surrounded by brackets.  The
       default if no LESSBINFMT is specified is "*s<%02X>".  Warning: the  re-
       sult  of  expanding  the  character via LESSBINFMT must be less than 31
       characters.

       When the character set is utf-8, the LESSUTFBINFMT environment variable
       acts similarly to LESSBINFMT but it applies to Unicode code points that
       were successfully decoded but are unsuitable for display  (e.g.,  unas-
       signed  code  points).   Its  default  value is "<U+%04lX>".  Note that
       LESSUTFBINFMT and LESSBINFMT  share  their  display  attribute  setting
       ("*x")  so specifying one will affect both; LESSUTFBINFMT is read after
       LESSBINFMT so its setting, if any,  will  have  priority.   Problematic
       octets  in  a  UTF-8  file (octets of a truncated sequence, octets of a
       complete but non-shortest form  sequence,  illegal  octets,  and  stray
       trailing  octets)  are displayed individually using LESSBINFMT so as to
       facilitate diagnostic of how the UTF-8 file is ill-formed.

PROMPTS
       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:

       %bX    Replaced by the byte offset into the current input file.  The  b
              is followed by a single character (shown as X above) which spec-
              ifies the line whose byte offset is to be used.  If the  charac-
              ter  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 bot-
              tom  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.

       %c     Replaced by the column number of the text appearing in the first
              column of the screen.

       %dX    Replaced by the page number of a line in the  input  file.   The
              line to be used is determined by the X, as with the %b option.

       %D     Replaced  by  the  number of pages in the input file, or equiva-
              lently, the page number of the last line in the input file.

       %E     Replaced by the name of the editor (from the VISUAL  environment
              variable,  or  the  EDITOR environment variable if VISUAL is not
              defined).  See the discussion of the LESSEDIT feature below.

       %f     Replaced by the name of the current input file.

       %F     Replaced by the last component of 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.

       %L     Replaced by the line number of the last line in the input file.

       %m     Replaced by the total number of input files.

       %pX    Replaced  by  the  percent into the current input file, based on
              byte offsets.  The line used is determined by the X as with  the
              %b option.

       %PX    Replaced  by  the  percent into the current input file, based on
              line numbers.  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.

       %T     Normally expands to the word "file".  However if  viewing  files
              via  a  tags  list  using  the -t option, it expands to the word
              "tag".

       %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 evalu-
       ated.  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.

       ?B     True if the size of current input file is known.

       ?c     True if the text is horizontally shifted (%c is not zero).

       ?dX    True if the page number 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.

       ?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.

       ?pX    True  if  the percent into the current input file, based on byte
              offsets, of the specified line is known.

       ?PX    True if the percent into the current input file, based  on  line
              numbers, of the specified line is known.

       ?s     Same as "?B".

       ?x     True  if there is a next input file (that is, if the current in-
              put file is not the last one).

       Any characters other than the special ones (question mark,  colon,  pe-
       riod, 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 "Stan-
       dard input".

       ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-...

       This prompt would print the filename, if known.  The filename  is  fol-
       lowed  by  the  line  number, if known, otherwise the percent if known,
       otherwise the byte offset if known.  Otherwise, a dash is printed.  No-
       tice  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(%T %i of %m) ..?e(END) ?x- Next\: %x..%t";

       This prints the filename if this is the first prompt in  a  file,  fol-
       lowed  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 re-
       spectively).  Each is broken into two lines here for readability only.

       ?n?f%f .?m(%T %i of %m) ..?e(END) ?x- Next\: %x.:
            ?pB%pB\%:byte %bB?s/%s...%t

       ?f%f .?n?m(%T %i of %m) ..?ltlines %lt-%lb?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(%T %i of %m) .?ltlines %lt-%lb?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 command is invoked.  The LESSEDIT string is  ex-
       panded  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 variable can be changed to modify this default.

SECURITY
       When  the  environment  variable LESSSECURE is set to 1, less runs in a
       "secure" mode.  This means these features are disabled:

              !      the shell command

              |      the pipe command

              :e     the examine command.

              v      the editing command

              s  -o  log files

              -k     use of lesskey files

              -t     use of tags files

                     metacharacters in filenames, such as *

                     filename completion (TAB, ^L)

       Less can also be compiled to be permanently in "secure" mode.

COMPATIBILITY WITH MORE
       If the environment variable LESS_IS_MORE is set to 1, or if the program
       is  invoked via a file link named "more", less behaves (mostly) in con-
       formance with the POSIX "more" command specification.   In  this  mode,
       less behaves differently in these ways:

       The -e option works differently.  If the -e option is not set, less be-
       haves as if the -e option were set.  If the -e option is set, less  be-
       haves as if the -E option were set.

       The  -m  option  works  differently.   If the -m option is not set, the
       medium prompt is used, and it is prefixed with the  string  "--More--".
       If the -m option is set, the short prompt is used.

       The  -n  option acts like the -z option.  The normal behavior of the -n
       option is unavailable in this mode.

       The parameter to the -p option is taken to be  a  less  command  rather
       than a search pattern.

       The  LESS  environment  variable  is  ignored, and the MORE environment
       variable is used in its place.

ENVIRONMENT VARIABLES
       Environment variables may be specified either in the system environment
       as  usual,  or in a lesskey (1) file.  If environment variables are de-
       fined in more than one place, variables defined in a local lesskey file
       take precedence over variables defined in the system environment, which
       take precedence over variables defined in the system-wide lesskey file.

       COLUMNS
              Sets the number of columns on the screen.  Takes precedence over
              the  number  of columns specified by the TERM variable.  (But if
              you  have  a  windowing  system  which  supports  TIOCGWINSZ  or
              WIOCGETD,  the  window  system's  idea  of the screen size takes
              precedence over the LINES and COLUMNS environment variables.)

       EDITOR The name of the editor (used for the v command).

       HOME   Name of the user's home directory (used to find a  lesskey  file
              on Unix and OS/2 systems).

       HOMEDRIVE, HOMEPATH
              Concatenation  of  the  HOMEDRIVE and HOMEPATH environment vari-
              ables is the name of the user's home directory if the HOME vari-
              able is not set (only in the Windows version).

       INIT   Name  of  the user's init directory (used to find a lesskey file
              on OS/2 systems).

       LANG   Language for determining the character set.

       LC_CTYPE
              Language for determining the character set.

       LESS   Options which are passed to less automatically.

       LESSANSIENDCHARS
              Characters which may end an ANSI color escape sequence  (default
              "m").

       LESSANSIMIDCHARS
              Characters  which  may  appear between the ESC character and the
              end  character  in  an  ANSI  color  escape  sequence   (default
              "0123456789:;[?!"'#%()*+ ".

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

       LESSCHARDEF
              Defines a character set.

       LESSCHARSET
              Selects a predefined character set.

       LESSCLOSE
              Command line to invoke the (optional) input-postprocessor.

       LESSECHO
              Name of the lessecho program (default "lessecho").  The lessecho
              program is needed to expand metacharacters, such as * and ?,  in
              filenames on Unix systems.

       LESSEDIT
              Editor  prototype  string (used for the v command).  See discus-
              sion under PROMPTS.

       LESSGLOBALTAGS
              Name of the command used by the -t option to find  global  tags.
              Normally should be set to "global" if your system has the global
              (1) command.  If not set, global tags are not used.

       LESSHISTFILE
              Name of the history file used to remember  search  commands  and
              shell  commands  between  invocations of less.  If set to "-" or
              "/dev/null", a  history  file  is  not  used.   The  default  is
              "$HOME/.lesshst"  on  Unix  systems, "$HOME/_lesshst" on DOS and
              Windows systems, or "$HOME/lesshst.ini"  or  "$INIT/lesshst.ini"
              on OS/2 systems.

       LESSHISTSIZE
              The maximum number of commands to save in the history file.  The
              default is 100.

       LESSKEY
              Name of the default lesskey(1) file.

       LESSKEY_SYSTEM
              Name of the default system-wide lesskey(1) file.

       LESSMETACHARS
              List of characters which are considered "metacharacters" by  the
              shell.

       LESSMETAESCAPE
              Prefix  which  less will add before each metacharacter in a com-
              mand sent to the shell.  If LESSMETAESCAPE is an  empty  string,
              commands  containing  metacharacters  will  not be passed to the
              shell.

       LESSOPEN
              Command line to invoke the (optional) input-preprocessor.

       LESSSECURE
              Runs less in "secure" mode.  See discussion under SECURITY.

       LESSSEPARATOR
              String to be appended to a directory name  in  filename  comple-
              tion.

       LESSUTFBINFMT
              Format for displaying non-printable Unicode code points.

       LESS_IS_MORE
              Emulate the more (1) command.

       LINES  Sets  the  number of lines on the screen.  Takes precedence over
              the number of lines specified by the TERM variable.  (But if you
              have  a  windowing system which supports TIOCGWINSZ or WIOCGETD,
              the window system's idea of the  screen  size  takes  precedence
              over the LINES and COLUMNS environment variables.)

       MORE   Options  which  are passed to less automatically when running in
              more compatible mode.

       PATH   User's search path (used to find a lesskey file  on  MS-DOS  and
              OS/2 systems).

       SHELL  The  shell  used  to execute the ! command, as well as to expand
              filenames.

       TERM   The type of terminal on which less is being run.

       VISUAL The name of the editor (used for the v command).

SEE ALSO
       lesskey(1)

COPYRIGHT
       Copyright (C) 1984-2016  Mark Nudelman

       less is part of the GNU project and is free software.  You  can  redis-
       tribute  it and/or modify it under the terms of either (1) the GNU Gen-
       eral Public License as published by the Free  Software  Foundation;  or
       (2) the Less License.  See the file README in the less distribution for
       more details regarding redistribution.  You should have received a copy
       of  the  GNU General Public License along with the source for less; see
       the file COPYING.  If not, write to the Free  Software  Foundation,  59
       Temple  Place, Suite 330, Boston, MA  02111-1307, USA.  You should also
       have received a copy of the Less License; see the file LICENSE.

       less is distributed in the hope that it will be useful, but WITHOUT ANY
       WARRANTY;  without even the implied warranty of MERCHANTABILITY or FIT-
       NESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License  for
       more details.

AUTHOR
       Mark Nudelman
       Send bug reports or comments to <bug-less@gnu.org>
       See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
       of known bugs in less.
       For more information, see the less homepage at
       http://www.greenwoodsoftware.com/less.

                           Version 487: 25 Oct 2016                    LESS(1)

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