8.1 Shell Introduction 8.2 command History 8.3 command completion and alias 8.4 wildcard 8.5 input/output weight

8.1 Shell Introduction: Can be divided into interactive and batch processing
Interactive: The user executes a command every input immediately
Batch: The user writes the full shell script in advance, and the shell executes many commands of the script

8.2 Command History




Permanent Save History Command: Chattr +a ~/.bash_history (+a permission, only allowed to increase not delete)
！！ Represents the execution of the previous command
！ N
！ Word

9.8.3 command Completion and aliases
#yum install-y bash-completion installation parameters after completion of the relevant source need to restart the machine before it takes effect
tab, tap, match commands and parameters, double tap to display matching information for selection

8.4 Wildcard Characters


8.5 Input and output redirection

          输出重定向到一个文件或设备 覆盖原来的文件

! Output redirected to a file or device forcing overwriting of the original file
> Output redirected to a file or device to append the original file
< redirect input to a program
2> redirects a standard error output to a file or device overwriting the original file B-shell
2>> redirect a standard error output to a file or device appended to the original file
2>&1 redirect a standard error output to the standard output note: 1 could be the standard output.
& redirect a standard error output to a file or device to overwrite the original file C-shell
|& to send a standard error pipe to another command as input

8.1 Shell Introduction 8.2 command History 8.3 command completion and alias 8.4 wildcard 8.5 input/output weight