shell more less cat

cat        连续显示、查看文件内容
more        分页查看文件内容
less 分页可控制查看文件内容

通俗点说：
cat一次性把文件内容全部显示出来，管你看不看得清，显示完了cat命令就返回了，不能进行交互式操作，适合察看内容短小、不超过一屏的文件；
more比cat强大一点，支持分页显示，你可以ctrl+B ctrl+F .....上下滚屏，但是不支持像shift+G（跳到文件尾）这种操作；
less比more更强大一点，支持各种命令，随便翻页、跳转、查找.....想怎么看，就怎么看，爱怎么看，就怎么看。
                   SUMMARY OF LESS COMMANDS
 
      Commands marked with * may be preceded by a number, N.
 
      Notes in parentheses indicate the behavior if N is given.
 
  h  H                 Display this help.
 
  q  :q  Q  :Q  ZZ     Exit.
 
---------------------------------------------------------------------------
 
                           MOVING
 
  e  ^E  j  ^N  CR  *  Forward  one line   (or N lines).
 
  y  ^Y  k  ^K  ^P  *  Backward one line   (or N lines).
 
  f  ^F  ^V  SPACE  *  Forward  one window (or N lines).
 
  b  ^B  ESC-v      *  Backward one window (or N lines).
 
  z                 *  Forward  one window (and set window to N).
 
  w                 *  Backward one window (and set window to N).
 
  ESC-SPACE         *  Forward  one window, but don't stop at end-of-file.
 
  d  ^D             *  Forward  one half-window (and set half-window to N).
 
  u  ^U             *  Backward one half-window (and set half-window to N).
 
  ESC-)  RightArrow *  Left  one half screen width (or N positions).
 
  ESC-(  LeftArrow  *  Right one half screen width (or N positions).
 
  F                    Forward forever; like "tail -f".
 
  r  ^R  ^L            Repaint screen.
 
  R                    Repaint screen, discarding buffered input.
 
        ---------------------------------------------------
 
        Default "window" is the screen height.
 
        Default "half-window" is half of the screen height.
 
---------------------------------------------------------------------------
 
                          SEARCHING
 
  /pattern          *  Search forward for (N-th) matching line.
 
  ?pattern          *  Search backward for (N-th) matching line.
 
  n                 *  Repeat previous search (for N-th occurrence).
 
  N                 *  Repeat previous search in reverse direction.
 
  ESC-n             *  Repeat previous search, spanning files.
 
  ESC-N             *  Repeat previous search, reverse dir. & spanning files.
 
  ESC-u                Undo (toggle) search highlighting.
 
        ---------------------------------------------------
 
        Search patterns may be modified by one or more of:
 
        ^N or !  Search for NON-matching lines.
 
        ^E or *  Search multiple files (pass thru END OF FILE).
 
        ^F or @  Start search at FIRST file (for /) or last file (for ?).
 
        ^K       Highlight matches, but don't move (KEEP position).
 
        ^R       Don't use REGULAR EXPRESSIONS.
 
---------------------------------------------------------------------------
 
                           JUMPING
 
  g  <  ESC-<       *  Go to first line in file (or line N).
 
  G  >  ESC->       *  Go to last line in file (or line N).
 
  p  %              *  Go to beginning of file (or N percent into file).
 
  t                 *  Go to the (N-th) next tag.
 
  T                 *  Go to the (N-th) previous tag.
 
  {  (  [           *  Find close bracket } ) ].
 
  }  )  ]           *  Find open bracket { ( [.
 
  ESC-^F <c1> <c2>  *  Find close bracket <c2>.
 
  ESC-^B <c1> <c2>  *  Find open bracket <c1> 
        ---------------------------------------------------
 
        Each "find close bracket" command goes forward to the close bracket 
          matching the (N-th) open bracket in the top line.
 
        Each "find open bracket" command goes backward to the open bracket 
          matching the (N-th) close bracket in the bottom line.
 
  m<letter>            Mark the current position with <letter>.
 
  '<letter>            Go to a previously marked position.
 
  ''                   Go to the previous position.
 
  ^X^X                 Same as '.
 
        ---------------------------------------------------
 
        A mark is any upper-case or lower-case letter.
 
        Certain marks are predefined:
 
             ^  means  beginning of the file
 
             $  means  end of the file
 
---------------------------------------------------------------------------
 
                        CHANGING FILES
 
  :e [file]            Examine a new file.
 
  ^X^V                 Same as :e.
 
  :n                *  Examine the (N-th) next file from the command line.
 
  :p                *  Examine the (N-th) previous file from the command line.
 
  :x                *  Examine the first (or N-th) file from the command line.
 
  :d                   Delete the current file from the command line list.
 
  =  ^G  :f            Print current file name.
 
---------------------------------------------------------------------------
 
                    MISCELLANEOUS COMMANDS
 
  -<flag>              Toggle a command line option [see OPTIONS below].
 
  --<name>             Toggle a command line option, by name.
 
  _<flag>              Display the setting of a command line option.
 
  __<name>             Display the setting of an option, by name.
 
  +cmd                 Execute the less cmd each time a new file is examined.
 
  !command             Execute the shell command with $SHELL.
 
  |Xcommand            Pipe file between current pos & mark X to shell command.
 
  v                    Edit the current file with $VISUAL or $EDITOR.
 
  V                    Print version number of "less".
 
---------------------------------------------------------------------------
 
                           OPTIONS
 
        Most options may be changed either on the command line,
 
        or from within less by using the - or -- command.
 
        Options may be given in one of two forms: either a single
 
        character preceded by a -, or a name preceeded by --.
 
  -?  ........  --help
 
                  Display help (from command line).
 
  -a  ........  --search-skip-screen
 
                  Forward search skips current screen.
 
  -b [N]  ....  --buffers=[N]
 
                  Number of buffers.
 
  -B  ........  --auto-buffers
 
                  Don't automatically allocate buffers for pipes.
 
  -c  -C  ....  --clear-screen  --CLEAR-SCREEN
 
                  Repaint by scrolling/clearing.
 
  -d  ........  --dumb
 
                  Dumb terminal.
 
  -D [xn.n]  .  --color=xn.n
 
                  Set screen colors. (MS-DOS only)
 
  -e  -E  ....  --quit-at-eof  --QUIT-AT-EOF
 
                  Quit at end of file.
 
  -f  ........  --force
 
                  Force open non-regular files.
 
  -F  ........  --quit-if-one-screen
 
                  Quit if entire file fits on first screen.
 
  -g  ........  --hilite-search
 
                  Highlight only last match for searches.
 
  -G  ........  --HILITE-SEARCH
 
                  Don't highlight any matches for searches.
 
  -h [N]  ....  --max-back-scroll=[N]
 
                  Backward scroll limit.
 
  -i  ........  --ignore-case
 
                  Ignore case in searches that do not contain uppercase.
 
  -I  ........  --IGNORE-CASE
 
                  Ignore case in all searches.
 
  -j [N]  ....  --jump-target=[N]
 
                  Screen position of target lines.
 
  -J  ........  --status-column
 
                  Display a status column at left edge of screen.
 
  -k [file]  .  --lesskey-file=[file]
 
                  Use a lesskey file.
 
  -L  ........  --no-lessopen
 
                  Ignore the LESSOPEN environment variable.
 
  -m  -M  ....  --long-prompt  --LONG-PROMPT
 
                  Set prompt style.
 
  -n  -N  ....  --line-numbers  --LINE-NUMBERS
 
                  Use line numbers.
 
  -o [file]  .  --log-file=[file]
 
                  Copy to log file (standard input only).
 
  -O [file]  .  --LOG-FILE=[file]
 
                  Copy to log file (unconditionally overwrite).
 
  -p [pattern]  --pattern=[pattern]
 
                  Start at pattern (from command line).
 
  -P [prompt]   --prompt=[prompt]
 
                  Define new prompt.
 
  -q  -Q  ....  --quiet  --QUIET  --silent --SILENT
 
                  Quiet the terminal bell.
 
  -r  -R  ....  --raw-control-chars  --RAW-CONTROL-CHARS
 
                  Output "raw" control characters.
 
  -s  ........  --squeeze-blank-lines
 
                  Squeeze multiple blank lines.
 
  -S  ........  --chop-long-lines
 
                  Chop long lines.
 
  -t [tag]  ..  --tag=[tag]
 
                  Find a tag.
 
  -T [tagsfile] --tag-file=[tagsfile]
 
                  Use an alternate tags file.
 
  -u  -U  ....  --underline-special  --UNDERLINE-SPECIAL
 
                  Change handling of backspaces.
 
  -V  ........  --version
 
                  Display the version number of "less".
 
  -w  ........  --hilite-unread
 
                  Highlight first new line after forward-screen.
 
  -W  ........  --HILITE-UNREAD
 
                  Highlight first new line after any forward movement.
 
  -x [N[,...]]  --tabs=[N[,...]]
 
                  Set tab stops.
 
  -X  ........  --no-init
 
                  Don't use termcap init/deinit strings.
 
                --no-keypad
 
                  Don't use termcap keypad init/deinit strings.
 
  -y [N]  ....  --max-forw-scroll=[N]
 
                  Forward scroll limit.
 
  -z [N]  ....  --window=[N]
 
                  Set size of window.
 
  -" [c[c]]  .  --quotes=[c[c]]
 
                  Set shell quote characters.
 
  -~  ........  --tilde
 
                  Don't display tildes after end of file.
 
  -# [N]  ....  --shift=[N]
 
                  Horizontal scroll amount (0 = one half screen width)
 
---------------------------------------------------------------------------
 
                          LINE EDITING
 
        These keys can be used to edit text being entered 
        on the "command line" at the bottom of the screen.
 
RightArrow                       ESC-l     Move cursor right one character.
 
LeftArrow                        ESC-h     Move cursor left one character.
 
CNTL-RightArrow  ESC-RightArrow  ESC-w     Move cursor right one word.
 
CNTL-LeftArrow   ESC-LeftArrow   ESC-b     Move cursor left one word.
 
HOME                             ESC-0     Move cursor to start of line.
 
END                              ESC-$     Move cursor to end of line.
 
BACKSPACE                                  Delete char to left of cursor.
 
DELETE                           ESC-x     Delete char under cursor.
 
CNTL-BACKSPACE   ESC-BACKSPACE             Delete word to left of cursor.
 
CNTL-DELETE      ESC-DELETE      ESC-X     Delete word under cursor.
 
CNTL-U           ESC (MS-DOS only)         Delete entire line.
 
UpArrow                          ESC-k     Retrieve previous command line.
 
DownArrow                        ESC-j     Retrieve next command line.
 
TAB                                        Complete filename & cycle.
 
SHIFT-TAB                        ESC-TAB   Complete filename & reverse cycle.
 
CNTL-L                                     Complete filename, list all.
 
HELP -- END -- Press g to see it again, or q when done