path: root/contrib/less/less.man

LESS(1)                                                                LESS(1)



NAME
       less - opposite of more

SYNOPSIS
       less -?
       less --help
       less -V
       less --version
       less [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]
            [-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 which allows backward  move-
       ment in the file as well as forward movement.  Also, 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
       "ESCAPE", 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
              below).   If  N  is  more  than  the screen size, only the final
              screenful is displayed.  Warning: some systems use ^V as a  spe-
              cial 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.

       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
              below).   If  N  is  more  than  the screen size, only the final
              screenful is displayed.

       w      Like ESC-v, but if N is specified, it  becomes  the  new  window
              size.

       y or ^Y or ^P or k or ^K
              Scroll backward N lines, default 1.  The entire N lines are 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.

       ESC-) or RIGHTARROW
              Scroll  horizontally right N characters, default half the screen
              width (see the -# option).  If  a  number  N  is  specified,  it
              becomes  the  default  for  future RIGHTARROW and LEFTARROW com-
              mands.  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
              becomes  the  default  for  future RIGHTARROW and LEFTARROW com-
              mands.

       r or ^R or ^L
              Repaint the screen.

       R      Repaint the screen, discarding any buffered  input.   Useful  if
              the file is changing while it is being viewed.

       F      Scroll  forward, and keep trying to read when the end of file is
              reached.  Normally this command would be used  when  already  at
              the  end of the file.  It is a way to monitor the tail of a file
              which is growing while it is being  viewed.   (The  behavior  is
              similar to the "tail -f" command.)

       g or < or ESC-<
              Go to line N in the file, default 1 (beginning of file).  (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.)

       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 second 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 line immediately  before  the
              top line displayed.

              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
                     options.

              ^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
              effect 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
              replaced 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
              entered 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
              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
              reset  the  option  to  its  default setting and print a message
              describing the new setting.  (The "-+X" command  does  the  same
              thing  as  "-+X"  on  the command line.)  This does not work for
              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 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
       unambiguous.  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
       appears  in  the LESS variable, it can be reset to its default value on
       the command line by beginning the command line option with "-+".

       For options like -P or -D which take a following string, a dollar  sign
       ($)  must be used to signal the end of the string.  For example, to set
       two -D options on MS-DOS, you must have a  dollar  sign  between  them,
       like this:

       LESS="-Dn9.1$-Ds4.1"


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

       -a or --search-skip-screen
              Causes searches to start after the last line  displayed  on  the
              screen,  thus  skipping  all  lines displayed on the screen.  By
              default, searches start at the second line  on  the  screen  (or
              after the last found line; see the -j option).

       -bn or --buffers=n
              Specifies  the  amount  of  buffer  space less will use for each
              file, in units of kilobytes (1024 bytes).   By  default  64K  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
              buffers  for  pipes,  so  that  only 64K (or the amount of space
              specified 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
              being  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.


       -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,  forward
              searches  begin  at  the line immediately after the target line,
              and backward searches begin at the target line.  For example, 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.

       -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
              effect.

       -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  when an interrupt 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  impossible  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
              option 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 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
              example, 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
              sequences 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  rather
              than  folded.  That is, the portion of a long line that does not
              fit in the screen width is not shown.  The default  is  to  fold
              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
              directory 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
              appear adjacent to an  underscore  character  are  treated  spe-
              cially:  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  bold-
              face  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.  Text which is overstruck or  under-
              lined 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
              default 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
              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 or --window=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 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
              example, if the screen is 24 lines, -z-4 sets the scrolling win-
              dow  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
              recalculated  if  the  terminal  window  is resized, so that the
              actual scroll remains at the specified fraction  of  the  screen
              width.

       --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.

       --follow-name
              Normally, if the input file is renamed while  an  F  command  is
              executing,  less  will  continue  to display the contents of the
              original file despite its  name  change.   If  --follow-name  is
              specified, during an F command less will periodically attempt to
              reopen 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
              renamed) file), less will display the contents of that new file.

       --     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
              every  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.

       DOWNARROW [ ESC-j ]
              Retrieve the next command line.

       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.


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
       details.

       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
       input  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
       replaced 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
       replaced  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 -
                 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
       replacement  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
                 ;;
            esac

       To  use  this  script,  put  it  where  it  can  be  executed  and  set
       LESSOPEN="|lesspipe.sh %s".  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 (|-), 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
       binary, and 8 is normal.  All characters after the last are taken to be
       the  same  as  the  last,  so characters 9 through 255 would be normal.
       (This is an example, and does not necessarily represent any real  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_TYPE or
       LANG environment variables, then the default character set is utf-8.

       If that string is not found, but your  system  supports  the  setlocale
       interface,  less  will  use  setlocale  to determine the character set.
       setlocale is controlled by setting the  LANG  or  LC_CTYPE  environment
       variables.

       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<%X>".  The default if no
       LESSBINFMT is specified is "*s<%02X>".  Warning: the result of  expand-
       ing 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.

       %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.

       %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
              input file is not the last one).

       Any characters other than  the  special  ones  (question  mark,  colon,
       period,  percent,  and  backslash) become literally part of the prompt.
       Any of the special characters may be included in the  prompt  literally
       by preceding it with a backslash.

       Some examples:

       ?f%f:Standard input.

       This  prompt prints the filename, if known; otherwise the string "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.
       Notice  how  each  question  mark  has a matching period, and how the %
       after the %pt is included literally by escaping it with a backslash.

       ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t

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

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

       ?f%f .?n?m(file %i of %m) ..?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(file %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
       expanded in the same way as the prompt strings.  The default value  for
       LESSEDIT is:

            %E ?lm+%lm. %f

       Note that this expands to the editor name, followed by a + and the line
       number, followed by the file name.  If your editor does not accept  the
       "+linenumber"  syntax,  or  has other differences in invocation syntax,
       the LESSEDIT 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
       behaves  as  if  the -E option were set.  If the -e option is set, less
       behaves as if the -e and -F options 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
       defined  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.)

       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) 1984-2009  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 <markn@greenwoodsoftware.com>
       See http://www.greenwoodsoftware.com/less/bugs.html for the latest list
       of known bugs in less.
       Send bug reports or comments to the above address or to
       bug-less@gnu.org.
       For more information, see the less homepage at
       http://www.greenwoodsoftware.com/less.



                           Version 436: 07 Jul 2009                    LESS(1)