Sức mạnh của Linux nằm ở chỗ lập trình Bash shell để tự động hóa mọi công việc ở Linux userspace hay Linux user space.
Linux userspace là không gian người dùng, là môi trường để người dùng thao tác với nó từ lớp vỏ (shell).
Học Linux kết quả cuối cùng cũng là để viết ra các bash script tự động hóa cài đặt, cấu hình, quản lí các phần mềm, ứng dụng chạy trên Linux.
Gần như 100% Linux server chạy ở chế độ dòng lệnh (text mode) chứ không phải chế độ đồ họa (graphic mode) như hệ điều hành Windows nên việc nắm vững các lệnh Linux giúp bạn khá nhiều trong việc quản lí Linux.
Linux man page là kinh thánh (bible) để chỉ bạn xài các lệnh Linux.
Linux man page có rất nhiều phím tắt để giúp bạn tìm kiếm được nội dung mình mong muốn trong trang hướng dẫn xài lệnh dài lê thê.
Dưới dây là các phím tắt của trang man page trên Linux.
SUMMARY OF LESS COMMANDS
Commands marked with * may be preceded by a number, N.
Notes in parentheses indicate the behavior if N is given.
A key preceded by a caret indicates the Ctrl key; thus ^K is ctrl-K.
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 * Right one half screen width (or N positions).
ESC-( LeftArrow * Left one half screen width (or N positions).
ESC-} ^RightArrow Right to last column displayed.
ESC-{ ^LeftArrow Left to first column.
F Forward forever; like "tail -f".
ESC-F Like F but stop when search pattern is found.
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.
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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.
ESC-U Clear search highlighting.
&pattern * Display only matching lines.
---------------------------------------------------
A search pattern may begin with 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.
^W WRAP search if no match found.
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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 top line with <letter>.
M<letter> Mark the current bottom line with <letter>.
'<letter> Go to a previously marked position.
'' Go to the previous position.
^X^X Same as '.
ESC-M<letter> Clear a mark.
---------------------------------------------------
A mark is any upper-case or lower-case letter.
Certain marks are predefined:
^ means beginning of the file
$ means end of the file
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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.
s file Save input to a file.
v Edit the current file with $VISUAL or $EDITOR.
V Print version number of "less".
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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 preceded by --.
-? ........ --help
Display help (from command line).
-a ........ --search-skip-screen
Search skips current screen.
-A ........ --SEARCH-SKIP-SCREEN
Search starts just after target line.
-b [N] .... --buffers=[N]
Number of buffers.
-B ........ --auto-buffers
Don't automatically allocate buffers for pipes.
-c ........ --clear-screen
Repaint by clearing rather than scrolling.
-d ........ --dumb
Dumb terminal.
-D xcolor . --color=xcolor
Set screen colors.
-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.
-K ........ --quit-on-intr
Exit less in response to ctrl-C.
-L ........ --no-lessopen
Ignore the LESSOPEN environment variable.
-m -M .... --long-prompt --LONG-PROMPT
Set prompt style.
-n -N .... --line-numbers --LINE-NUMBERS
Don't 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 (truncate) long lines rather than wrapping.
-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.
-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]
Set horizontal scroll amount (0 = one half screen width).
--file-size
Automatically determine the size of the input file.
--follow-name
The F command changes files if the input file is renamed.
--incsearch
Search file as each pattern character is typed in.
--line-num-width=N
Set the width of the -N line number field to N characters.
--mouse
Enable mouse input.
--no-keypad
Don't send termcap keypad init/deinit strings.
--no-histdups
Remove duplicates from command history.
--rscroll=C
Set the character used to mark truncated lines.
--save-marks
Retain marks across invocations of less.
--status-col-width=N
Set the width of the -J status column to N characters.
--use-backslash
Subsequent options use backslash as escape char.
--use-color
Enables colored text.
--wheel-lines=N
Each click of the mouse wheel moves N lines.
---------------------------------------------------------------------------
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.
ctrl-RightArrow ESC-RightArrow ESC-w ... Move cursor right one word.
ctrl-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.
ctrl-BACKSPACE ESC-BACKSPACE ........... Delete word to left of cursor.
ctrl-DELETE .... ESC-DELETE .... ESC-X ... Delete word under cursor.
ctrl-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.
ctrl-L ................................... Complete filename, list all.