Commands learned in this section: history, alias, ualias, \CMD
Skills learned in this section:
Features of bash
Cursor jumps
Viewing command history
Command history tricks
Aliasing
commands Command substitution
Filename wildcards
shell : shell
GUI ： Gnome, KDE, Xfce
CLI: sh, csh, ksh, bash, tcsh, zsh
Process: From the perspective of each process, only the kernel and the current process exist on the current host
A process is a copy of a program, a process is an instance of program execution
User working environment :
bash:
#: Administrator Command Prompt
$: normal user command prompt
Features of bash:
1. Command history, command completion
2, pipeline, redirection
3. Command alias
4. Command line editing
5. Command line expansion
6. File name wildcard
7. Variables
8. Programming
Command line editing :
Cursor jump :
Ctrl+a : Jump to the beginning of the command line
Ctrl+e : Jump to the end of the command line
Ctrl+u : delete the content from the cursor to the beginning of the command line
Ctrl+k : delete the content from the cursor to the end of the command line
Ctrl+l : clear screen
Command History :
history : View command history
-c: clear command history
-d OFFSET [n]: delete the command at the specified position
-w: save command history to history file
environment variable
PATH: command search path
HISTSIZE: command history buffer size (can be viewed with ' echo $HISTSIZE ')
Tips for using command history :
!n: execute the nth command in the command history;
!-n: Execute the nth last command in the command history;
!!: Execute the previous command;
!string: Execute the most recent command in the command history that begins with the specified string
!$: refer to the last parameter of the previous command, or use "Esc + .";
text related commands
查看：cat, tac, more, less, head, tail
Statistics: wc
Processing: tr, cut, join
Sort: sort
Uniq
command completion, path completion
Command completion: Search for executable files starting with the string we give in each path specified by the PATH environment variable. If there is more than one, tab twice to give a list; otherwise, it will be directly completed;
Path completion: search for each file name under the starting path we give, and try to complete it;
command alias
alias CMDALIAS='COMMAND [options] [arguments]'
Aliases defined in the shell are only valid in the current shell life cycle; aliases are only valid for the current shell process;
alias : Displays all currently aliased commands
ualias CMDALIAS : undo command alias
type COMMAND : see if the command is bound with additional parameters
\CMD : use the original properties of the parameterized command
Command substitution : $(COMMAND), backticks: `COMMAND`
The process of replacing a subcommand in a command with its execution result
Quotes supported by bash :
``: command substitution
"": Weak reference, which can implement variable substitution
'': strong reference, does not complete variable substitution
filename globbing, globbing
*: any character of any length
?: any single character
[]: matches any single character within the specified range
[abc], [am], [az], [AZ], [0-9], [a-zA-Z], [0-9a-zA-Z]
[:space:]: whitespace character
[:punct:]: punctuation mark
[:lower:]: lowercase letters
[:upper:]: uppercase letters
[:alpha:]: upper and lower case letters
[:digit:]: digit
[:alnum:]: numbers and uppercase and lowercase letters
How to get these lists: man 7 glob (I didn't succeed)
[^]: matches any single character outside the specified range
[[:alpha:]]*[[:space:]]*[[:alpha:]]: Get files that start with a letter, end with a letter, and have spaces in between
[[:alpha:]]*[[:space:]]*[^[:alpha:]]: Get files that start with letters, end with non-letters, and have spaces in between
practise:
1. Create a123, cd6, c78m, c1 my, mz, k 67, 8yu, 789 and other files; note that the above files are separated by commas, and other symbols are part of the file name;
2. Display all files starting with a or m;
ls [am]*
3. Display all files that contain numbers in their file names;
ls * [0-9] *
ls * [[: digit:]] *
4. Display all files that end with numbers and do not contain blanks in the file name;
ls *[^[:space:]]*[0-9] ?????????
5. Display files whose file names contain special symbols other than letters or numbers;
ls * [^ [: alnum:]] *