# 2.11BSD#431 - /usr/local/man/cat1/less.0

    LESS(LOCAL)	    UNIX Programmer's Manual	      LESS(LOCAL)

    NAME
         less - opposite of more

    SYNOPSIS
         less [-cdepstwmMqQuU] [-hN] [-b[fp]N] [-xN] [-[z]N]
    	  [-P[mM]string] [-llogfile] [+cmd]  [filename]...

    DESCRIPTION
         Less is a program similar to more (1), but which allows
         backwards movement 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 fas-
         ter than text editors like vi (1).  Less uses termcap, 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 an up-arrow.)

         Commands are based on both more and vi. Commands may be pre-
         ceeded 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.

         h	  Help: display a summary of these commands.  If you for-
    	  get all the other commands, remember this one.

         SPACE
    	  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.

         f or ^F
    	  Same as SPACE.

         b or ^B
    	  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.

         RETURN
    	  Scroll forward N lines, default 1.  The entire N lines
    	  are displayed, even if N is more than the screen size.

         e or ^E
    	  Same as RETURN.

         j or ^J
    	  Also the same as RETURN.

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         y or ^Y
    	  Scroll backward N lines, default 1.  The entire N lines
    	  are displayed, even if N is more than the screen size.

         k or ^K
    	  Same as y.

         d or ^D
    	  Scroll forward N lines, default 10.  If N is specified,
    	  it becomes the new default for subsequent d and u com-
    	  mands.

         u or ^U
    	  Scroll backward N lines, default 10.	If N is speci-
    	  fied, it becomes the new default for subsequent d and u
    	  commands.

         r or ^R or ^L
    	  Repaint the screen.

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

         g	  Go to line N in the file, default 1 (beginning of
    	  file).  (Warning: this may be slow if N is large.)

         G	  Go to line N in the file, default the end of the file.
    	  (Warning: this may be slow if standard input, rather
    	  than a file, is being read.)

         p	  Go to a position N percent into the file.  N should be
    	  between 0 and 100.  (This is possible if standard input
    	  is being read, but only if less has already read to the
    	  end of the file.  It is always fast, but not always
    	  useful.)

         %	  Same as p.

         m	  Followed by any lowercase letter, marks the current
    	  position with that letter.

         '	  (Single quote.) Followed by any lowercase letter,
    	  returns to the position which was previously marked
    	  with that letter.  Followed by another single quote,
    	  returns to the postion at which the last "large" move-
    	  ment command was executed.  All marks are lost when a
    	  new file is examined.

         /pattern
    	  Search forward in the file for the N-th line containing
    	  the pattern.	N defaults to 1.  The pattern is a

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    	  regular expression, as recognized by ed. The search
    	  starts at the second line displayed (but see the -t
    	  option, which changes this).

         ?pattern
    	  Search backward in the file for the N-th line contain-
    	  ing the pattern.  The search starts at the line immedi-
    	  ately before the top line displayed.

         n	  Repeat previous search, for N-th line containing the
    	  last pattern.

         E	  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.

         N	  Examine the next file (from the list of files given in
    	  the command line).  If a number N is specified (not to
    	  be confused with the command N), the N-th next file is
    	  examined.

         P	  Examine the previous file.  If a number N is specified,
    	  the N-th previous file is examined.

         = or ^G
    	  Prints some information about the file being viewed,
    	  including its name and the byte offset of the bottom
    	  line being displayed.  If possible, it also prints the
    	  length of the file and the percent of the file above
    	  the last displayed line.

         -	  Followed by one of the command line option letters (see
    	  below), this will toggle the setting of that option and
    	  print a message describing the new setting.

         +cmd Causes the specified cmd to be executed each time a new
    	  file is examined.  For example, +G causes less to ini-
    	  tially display each file starting at the end rather
    	  than the beginning.

         V	  Prints the version number of less being run.

         q	  Exits less.

         The following two commands may or may not be valid, depend-
         ing on your particular installation.

         v	  Invokes an editor to edit the current file being
    	  viewed.  The editor is taken from the environment vari-
    	  able EDITOR, or defaults to "vi".

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         ! shell-command
    	  Invokes a shell to run the shell-command given.

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

         Options are also taken from the environment variable "LESS".
         For example, if you like more-style prompting, to avoid typ-
         ing "less -m ..." each time less is invoked, you might tell
         csh:

         setenv LESS m

         or if you use sh:

         LESS=m; export LESS

         The environment variable is parsed before the command line,
         so command line options override the LESS environment vari-
         able.  A dollar sign ($) may be used to signal the end of an
         option string.  This is important only for options like -P
         which take a following string.

         -s   The -s option causes consecutive blank lines to be
    	  squeezed into a single blank line.  This is useful when
    	  viewing nroff output.

         -t   Normally, forward searches start just after the top
    	  displayed line (that is, at the second displayed line).
    	  Thus forward searches include the currently displayed
    	  screen.  The -t option causes forward searches to start
    	  just after the bottom line displayed, thus skipping the
    	  currently displayed screen.

         -m   Normally, less prompts with a colon.	The -m option
    	  causes less to prompt verbosely (like more), with the
    	  percent into the file.

         -M   The -M option causes less to prompt even more verbosely
    	  than more.

         -P   The -P option provides a way to tailor the three prompt
    	  styles to your own preference.  You would normally put
    	  this option in your LESS environment variable, rather
    	  than type it in with each less command.  Such an option
    	  must either be the last option in the LESS variable, or
    	  be terminated by a dollar sign.  -P followed by a
    	  string changes the default (short) prompt to that
    	  string.  -Pm changes the medium (-m) prompt to the
    	  string, and -PM changes the long (-M) prompt.  The
    	  string consists of a sequence of letters which are

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    	  replaced with certain predefined strings, as follows:
    	       F    file name
    	       f    file name, only once
    	       O    file n of n
    	       o    file n of n, only once
    	       b    byte offset
    	       p    percent into file
    	       P    percent if known, else byte offset
    	  Angle brackets, < and >, may be used to surround a
    	  literal string to be included in the prompt.	The
    	  defaults are "fo" for the short prompt, "foP" for the
    	  medium prompt, and "Fobp" for the long prompt.
    	  Example: Setting your LESS variable to "PmFOP$PMFObp"
    	  would change the medium and long prompts to always
    	  include the file name and "file n of n" message.
    	  Another example: Setting your LESS variable to
    	  "mPm<--Less-->FoPe" would change the medium prompt to
    	  the string "--Less--" followed by the file name and
    	  percent into the file.  It also selects the medium
    	  prompt as the default prompt (because of the first
    	  "m").

         -q   Normally, if an attempt is made to scroll past the end
    	  of the file or before the beginning of the file, the
    	  terminal bell is rung to indicate this fact.	The -q
    	  option tells less not to ring the bell at such times.
    	  If the terminal has a "visual bell", it is used
    	  instead.

         -Q   Even if -q is given, less will ring the bell on certain
    	  other errors, such as typing an invalid character.  The
    	  -Q option tells less to be quiet all the time; that is,
    	  never ring the terminal bell.  If the terminal has a
    	  "visual bell", it is used instead.

         -e   Normally the only way to exit less is via the "q" com-
    	  mand.  The -e option tells less to automatically exit
    	  the second time it reaches end-of-file.

         -u   If the -u option is given, backspaces are treated as
    	  printable characters; that is, they are sent to the
    	  terminal when they appear in the input.

         -U   If the -U option is given, backspaces are printed as
    	  the two character sequence "^H".

    	  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 charac-
    	  ters are treated specially: the overstruck text is

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    	  printed using the terminal's hardware boldface capabil-
    	  ity.	Other backspaces are deleted, along with the
    	  preceeding character.

         -w   Normally, less uses a tilde character to represent
    	  lines past the end of the file.  The -w option causes
    	  blank lines to be used instead.

         -d   Normally, less will complain if the terminal is dumb;
    	  that is, lacks some important capability, such as the
    	  ability to clear the screen or scroll backwards.  The
    	  -d option suppresses this complaint (but does not oth-
    	  erwise change the behavior of the program on a dumb
    	  terminal).

         -p   Normally, less will repaint the screen by scrolling
    	  from the bottom of the screen.  If the -p option is
    	  set, when less needs to change the entire display, it
    	  will clear the screen and paint from the top line down.

         -h   Normally, less will scroll backwards when backwards
    	  movement is necessary.  The -h option specifies a max-
    	  imum number of lines to scroll backwards.  If it is
    	  necessary to move backwards more than this many lines,
    	  the screen is repainted in a forward direction.  (If
    	  the terminal does not have the ability to scroll back-
    	  wards, -h0 is implied.)

         -[z] When given a backwards or forwards window command, less
    	  will by default scroll backwards or forwards one
    	  screenful of lines. The -zn option changes the default
    	  scrolling window size to n lines.  If n is greater than
    	  the screen size, the scrolling window size will be set
    	  to one screenful. Note that the "z" is optional for
    	  compatibility with more.

         -x   The -xn option sets tab stops every n positions.  The
    	  default for n is 8.

         -l   The -l option, followed immediately by a filename, will
    	  cause 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.

         -b   The -bn option tells less to use a non-standard buffer
    	  size.  There are two standard (default) buffer sizes,
    	  one is used when a file is being read and the other
    	  when a pipe (standard input) is being read.  The
    	  current defaults are 5 buffers for files and 12 for
    	  pipes.  (Buffers are 1024 bytes.) The number n speci-
    	  fies a different number of buffers to use.  The -b may
    	  be followed by "f", in which case only the file default

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    	  is changed, or by "p" in which case only the pipe
    	  default is changed.  Otherwise, both are changed.

         -c   Normally, when data is read by less, it is scanned to
    	  ensure that bit 7 (the high order bit) is turned off in
    	  each byte read, and to ensure that there are no null
    	  (zero) bytes in the data (null bytes are turned into
    	  "@" characters).  If the data is known to be "clean",
    	  the -c option will tell less to skip this checking,
    	  causing an imperceptible speed improvement.  (However,
    	  if the data is not "clean", unpredicatable results may
    	  occur.)

         +	  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 occurence of "xyz" in the file.
    	  As a special case, +<number> acts like +<number>g; that
    	  is, it starts the display at the specified line number
    	  (however, see the caveat under the "g" command above).
    	  If the option starts with ++, the initial command
    	  applies to every file being viewed, not just the first
    	  one.	The + command described previously may also be
    	  used to set (or change) an initial command for every
    	  file.

    BUGS
         When used on standard input (rather than a file), you can
         move backwards only a finite amount, corresponding to that
         portion of the file which is still buffered.  The -b option
         may be used to expand the buffer space.

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