1.1 Shell prompt
[Email protected] ~]$
If the last character is "#", it indicates that the current Terminal session has Superuser privileges. This permission can be obtained by logging in with the root user or using a terminal that provides superuser privileges.
The prompt is defined by an environment variable named PS1 (Prompt string 1).
1.2 Auto-Completing
Auto-completion can be applied to path names, variables (words starting with $), user names (beginning with ~), commands (the first word at the command line), host names (words begin with @, only valid for host names under/etc/hosts)
Command |
Role |
alt-$ |
Displays all possible items. Equivalent to pressing TAB two times |
alt-* |
Insert all possible matches |
1.2 Command line History
The history command outputs a historical record, which defaults to 500.
History commands
Command |
Role |
Ctrl-p |
Move to previous history, equal up Arrow |
Ctrl-n |
Move to the next history, equal to the down arrow |
alt-< |
Move to the beginning of the history record |
Alt-> |
Move to the end of the history, which is the current command line |
Alt-p |
Non-incremental search. Enter search string and type Enter to start search |
Alt-n |
Forward non-Incremental search |
Ctrl-o |
Executes the history item and jumps to the next item after execution. Used to perform a series of historical records |
Ctrl-r |
Reverse incremental search history; Find next match when searching |
Ctrl-j |
Copy the search content to the current command line (press the left and RIGHT arrow keys to copy, and press ENTER to execute the command immediately) |
Ctrl-g or C |
Exit Search |
!! |
Repeat the last command, equivalent to the UP ARROW +enter |
!number |
command to execute history number line |
! String |
Executes the most recent history that begins with a string |
!? String |
Executes the most recent history that contains a string |
1.3 Copy and paste
* You can't use ctrl-c and ctrl-v.
Copy |
Paste |
left mouse button to select text (or double-click to select Word) |
Middle mouse button |
Ctrl-shift-c |
Ctrl-shift-v |
Ctrl-insert |
Shift-insert |
1.4 Virtual Terminal
CTRL-ALT-F1 ~ F6: Switch to 1~6 virtual terminal by the graphical desktop system
ALT-F1 ~ F6: Switch between virtual terminals 1~6
Alt-f7: Back to the graphical desktop system by the virtual terminal
1.5 wildcard characters
Called wildcards or globbing to match a set of file names. Can be used with any command that uses a file name to make arguments.
Note: Use the character range notation sparingly [a-z][a-z]
Wildcard characters |
Matching items |
* |
Matches any number of characters (contains 0) |
? |
Match any one character (0 not included) |
[Characters] |
Match any character within a character set |
[!characters] |
Match any character that is not in character set |
[[: Class:]] |
Match any character within an in-class character |
Character class |
Description |
[: Alnum:] |
Alphabet Set or number set |
[: Alpha:] |
Alphabet Set |
[:d Igit:] |
Number Set |
[: Lower:] |
Small Letter Set |
[: Upper:] |
Caps set |
1.6 Redirects
Linux provides standard input "0", Standard output "1", standard error "2".
">": Redirect the standard output to a file, emptying the original file contents first
Use "> filename" to delete the contents of a file
"<": Read the contents of the file as a standard input command
">>": Redirect standard output to a file, using append mode
"|" : pipe, the standard output of the previous command as standard input for the next command
Simultaneous redirection of standard output and standard errors:
Command > File 2>&1
or new bash-supported command &> file
The redirection of standard errors occurs after standard output redirection, so command 2>&1 >file is wrong.
Ignore output: Redirect output or standard error to file/dev/null.
Ignore all output: command >/dev/null 2>&1
Ignore error: Command 2>/dev/null
1.7 Extensions
Each time the shell command executes, it will be expanded (expansion). Echo makes it easy to verify the extended results. These extensions include:
Path name extension (wildcard characters are used)
Wavy line Extension (~ or ~user, extended to User's home directory)
Arithmetic extension, $ (expression), note all integer operations, support four and take remainder "%", take power "* *", ignore spaces
Curly brace Extension
$ echo {1..5} Output 1 2 3 4 5
$ echo {G... A} output G F E D C B A
$ echo {a{1, 2}, B{3, 4}} output A1 A2 B3 B4
Parameter extensions, such as $path parameters
Command substitution, such as $ (LS) or ' ls '
1.8 References
References can avoid shell extensions. References a strong reference that contains both a weak reference and a single quotation mark.
Weak references: Some special characters lose special meaning, keep the dollar sign "$", backslash "\", anti-quote "'". Therefore, word separation, pathname expansion, wavy line expansion, and braces extension are invalidated. Parameter expansion, arithmetic expansion, and command substitution are still valid.
Strong reference: Suppresses all extensions.
Escape character "\": Output "$", "\", "" "or output escape character" \ n "in a weak reference. Eliminate the meaning of the shell special characters on the command line, such as "$", "!", "&", Spaces
1.9 Shell shortcut key cursor movement
Key combinations |
Role |
Ctrl-a |
Cursor to beginning of line |
Ctrl-e |
Cursor to end of line |
Ctrl-f |
Move forward one character, equivalent to the right arrow |
Ctrl-b |
Move back one character, equivalent to the left arrow |
Alt-f |
Move forward one word, navigate to the word |
Alt-b |
Move back one word and position to the beginning of the letter |
Ctrl-l |
Clear the screen and move the cursor to the beginning of the line, equivalent to clear |
Modify text
Key combinations |
Role |
Ctrl-d |
Remove the character at the cursor |
Ctrl-t |
The character at the cursor and the preceding character are swapped |
Alt-t |
The word at the cursor and the previous word swap |
Alt-l |
lowercase from cursor to Word end |
Alt-u |
Capitalize from cursor to Word end |
Cut (Killing) and paste (yanking)
A buffer in which the clipped content exists as a kill-ring
Key combinations |
Role |
Ctrl-k |
Cut from cursor to end of line |
Ctrl-u |
Cut from cursor to beginning of line |
Alt-d |
Cut from cursor to current suffix |
Alt-backspace |
Cut from cursor to prefix, if already at the beginning, cut one single time before |
Ctrl-y |
Paste |
Shell command-line operations