使用cat more less都可以查看文本內容，但是它們三者有什麼區別呢？
more和less的功能完全重複嗎？
以下是我個人的總結，歡迎大家一起來分享
cat 連續顯示、查看文件內容
more 分頁查看文件內容
less 分頁可控制查看文件內容
通俗點說：
cat一次性把文件內容全部顯示出來，管你看不看得清，顯示完了cat命令就返回了，不能進行交互式操作，適合察看內容短小、不超過一屏的文件；
more比cat強大一點，支持分頁顯示，你可以ctrl+B ctrl+F .....上下滾屏，但是不支持像shift+G（跳到文件尾）這種操作；
less比more更強大一點，支持各種命令，隨便翻頁、跳轉、查找.....想怎麼看，就怎麼看，愛怎麼看，就怎麼看。
附less的幫助內容
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SUMMARY OF LESS COMMANDS
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Commands marked with * may be preceded by a number, N.
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Notes in parentheses indicate the behavior if N is given.
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h H Display this help.
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q :q Q :Q ZZ Exit.
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---------------------------------------------------------------------------
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MOVING
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e ^E j ^N CR * Forward one line (or N lines).
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y ^Y k ^K ^P * Backward one line (or N lines).
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f ^F ^V SPACE * Forward one window (or N lines).
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b ^B ESC-v * Backward one window (or N lines).
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z * Forward one window (and set window to N).
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w * Backward one window (and set window to N).
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ESC-SPACE * Forward one window, but don't stop at end-of-file.
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d ^D * Forward one half-window (and set half-window to N).
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u ^U * Backward one half-window (and set half-window to N).
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ESC-) RightArrow * Left one half screen width (or N positions).
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ESC-( LeftArrow * Right one half screen width (or N positions).
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F Forward forever; like "tail -f".
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r ^R ^L Repaint screen.
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R Repaint screen, discarding buffered input.
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---------------------------------------------------
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Default "window" is the screen height.
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Default "half-window" is half of the screen height.
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---------------------------------------------------------------------------
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SEARCHING
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/pattern * Search forward for (N-th) matching line.
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?pattern * Search backward for (N-th) matching line.
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n * Repeat previous search (for N-th occurrence).
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N * Repeat previous search in reverse direction.
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ESC-n * Repeat previous search, spanning files.
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ESC-N * Repeat previous search, reverse dir. & spanning files.
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ESC-u Undo (toggle) search highlighting.
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---------------------------------------------------
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Search patterns may be modified by one or more of:
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^N or ! Search for NON-matching lines.
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^E or * Search multiple files (pass thru END OF FILE).
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^F or @ Start search at FIRST file (for /) or last file (for ?).
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^K Highlight matches, but don't move (KEEP position).
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^R Don't use REGULAR EXPRESSIONS.
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---------------------------------------------------------------------------
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JUMPING
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g < ESC-< * Go to first line in file (or line N).
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G > ESC-> * Go to last line in file (or line N).
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p % * Go to beginning of file (or N percent into file).
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t * Go to the (N-th) next tag.
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T * Go to the (N-th) previous tag.
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{ ( [ * Find close bracket } ) ].
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} ) ] * Find open bracket { ( [.
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ESC-^F <c1> <c2> * Find close bracket <c2>.
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ESC-^B <c1> <c2> * Find open bracket <c1>
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---------------------------------------------------
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Each "find close bracket" command goes forward to the close bracket
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matching the (N-th) open bracket in the top line.
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Each "find open bracket" command goes backward to the open bracket
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matching the (N-th) close bracket in the bottom line.
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m<letter> Mark the current position with <letter>.
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'<letter> Go to a previously marked position.
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'' Go to the previous position.
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^X^X Same as '.
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---------------------------------------------------
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A mark is any upper-case or lower-case letter.
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Certain marks are predefined:
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^ means beginning of the file
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$ means end of the file
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---------------------------------------------------------------------------
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CHANGING FILES
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:e [file] Examine a new file.
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^X^V Same as :e.
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:n * Examine the (N-th) next file from the command line.
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:p * Examine the (N-th) previous file from the command line.
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:x * Examine the first (or N-th) file from the command line.
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:d Delete the current file from the command line list.
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= ^G :f Print current file name.
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---------------------------------------------------------------------------
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MISCELLANEOUS COMMANDS
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-<flag> Toggle a command line option [see OPTIONS below].
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--<name> Toggle a command line option, by name.
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_<flag> Display the setting of a command line option.
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__<name> Display the setting of an option, by name.
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+cmd Execute the less cmd each time a new file is examined.
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!command Execute the shell command with $SHELL.
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|Xcommand Pipe file between current pos & mark X to shell command.
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v Edit the current file with $VISUAL or $EDITOR.
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V Print version number of "less".
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---------------------------------------------------------------------------
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OPTIONS
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Most options may be changed either on the command line,
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or from within less by using the - or -- command.
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Options may be given in one of two forms: either a single
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character preceded by a -, or a name preceeded by --.
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-? ........ --help
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Display help (from command line).
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-a ........ --search-skip-screen
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Forward search skips current screen.
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-b [N] .... --buffers=[N]
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Number of buffers.
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-B ........ --auto-buffers
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Don't automatically allocate buffers for pipes.
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-c -C .... --clear-screen --CLEAR-SCREEN
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Repaint by scrolling/clearing.
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-d ........ --dumb
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Dumb terminal.
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-D [xn.n] . --color=xn.n
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Set screen colors. (MS-DOS only)
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-e -E .... --quit-at-eof --QUIT-AT-EOF
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Quit at end of file.
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-f ........ --force
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Force open non-regular files.
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-F ........ --quit-if-one-screen
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Quit if entire file fits on first screen.
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-g ........ --hilite-search
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Highlight only last match for searches.
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-G ........ --HILITE-SEARCH
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Don't highlight any matches for searches.
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-h [N] .... --max-back-scroll=[N]
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Backward scroll limit.
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-i ........ --ignore-case
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Ignore case in searches that do not contain uppercase.
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-I ........ --IGNORE-CASE
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Ignore case in all searches.
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-j [N] .... --jump-target=[N]
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Screen position of target lines.
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-J ........ --status-column
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Display a status column at left edge of screen.
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-k [file] . --lesskey-file=[file]
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Use a lesskey file.
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-L ........ --no-lessopen
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Ignore the LESSOPEN environment variable.
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-m -M .... --long-prompt --LONG-PROMPT
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Set prompt style.
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-n -N .... --line-numbers --LINE-NUMBERS
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Use line numbers.
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-o [file] . --log-file=[file]
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Copy to log file (standard input only).
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-O [file] . --LOG-FILE=[file]
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Copy to log file (unconditionally overwrite).
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-p [pattern] --pattern=[pattern]
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Start at pattern (from command line).
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-P [prompt] --prompt=[prompt]
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Define new prompt.
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-q -Q .... --quiet --QUIET --silent --SILENT
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Quiet the terminal bell.
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-r -R .... --raw-control-chars --RAW-CONTROL-CHARS
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Output "raw" control characters.
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-s ........ --squeeze-blank-lines
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Squeeze multiple blank lines.
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-S ........ --chop-long-lines
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Chop long lines.
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-t [tag] .. --tag=[tag]
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Find a tag.
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-T [tagsfile] --tag-file=[tagsfile]
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Use an alternate tags file.
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-u -U .... --underline-special --UNDERLINE-SPECIAL
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Change handling of backspaces.
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-V ........ --version
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Display the version number of "less".
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-w ........ --hilite-unread
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Highlight first new line after forward-screen.
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-W ........ --HILITE-UNREAD
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Highlight first new line after any forward movement.
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-x [N[,...]] --tabs=[N[,...]]
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Set tab stops.
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-X ........ --no-init
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Don't use termcap init/deinit strings.
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--no-keypad
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Don't use termcap keypad init/deinit strings.
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-y [N] .... --max-forw-scroll=[N]
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Forward scroll limit.
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-z [N] .... --window=[N]
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Set size of window.
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-" [c[c]] . --quotes=[c[c]]
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Set shell quote characters.
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-~ ........ --tilde
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Don't display tildes after end of file.
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-# [N] .... --shift=[N]
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Horizontal scroll amount (0 = one half screen width)
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---------------------------------------------------------------------------
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LINE EDITING
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These keys can be used to edit text being entered
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on the "command line" at the bottom of the screen.
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RightArrow ESC-l Move cursor right one character.
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LeftArrow ESC-h Move cursor left one character.
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CNTL-RightArrow ESC-RightArrow ESC-w Move cursor right one word.
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CNTL-LeftArrow ESC-LeftArrow ESC-b Move cursor left one word.
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HOME ESC-0 Move cursor to start of line.
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END ESC-$ Move cursor to end of line.
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BACKSPACE Delete char to left of cursor.
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DELETE ESC-x Delete char under cursor.
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CNTL-BACKSPACE ESC-BACKSPACE Delete word to left of cursor.
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CNTL-DELETE ESC-DELETE ESC-X Delete word under cursor.
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CNTL-U ESC (MS-DOS only) Delete entire line.
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UpArrow ESC-k Retrieve previous command line.
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DownArrow ESC-j Retrieve next command line.
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TAB Complete filename & cycle.
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SHIFT-TAB ESC-TAB Complete filename & reverse cycle.
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CNTL-L Complete filename, list all.
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HELP -- END -- Press g to see it again, or q when done
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複製代碼
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