3: The basic features of the Bash
View (1) command history
history [options] [history command to save the file]
Options: -c: Clear History command
-w: the cache write history command history command to save the file. If you do not manually specified history commands to save the file, then save the file into the default history command ~ / .bash_history in.
(2) the command call history
There are several ways so if you want to use the original command history:
use the down arrow recall previous commands.
Use "! N" history repeats implementing Article n command.
Use "!!" repeat the last command.
Use "! String" repeat the last command beginning with that string.
Use "! $" Repeat the last parameter of a command.
(3) Input and output redirection
Equipment Equipment Type a file name file descriptor
Keyboard / dev / stdin 0 standard input
Display / dev / stdout 1 standard output
Display / dev / stderr 2 stderr
(1) standard output redirection
Command> file
Overlaid manner, the output of the correct command input
Or the device to which the specified file.
Command >> file
In additional embodiment, the output of the correct command input
Or the device to which the specified file.
(2) the standard error output redirection
Error command 2> file
Overlaid manner, the error output command input
Or the device to which the specified file.
Error command 2 >> file
In additional embodiment, the error output command input
Or the device to which the specified file.
(3) the correct output and error
While preserving
Command> file 2> & 1
Overlaid manner, and outputs the correct transmission errors
That are saved to a file with them.
Command >> file 2> & 1
In an additional manner, the correct output, and error output
That are saved to a file with them.
Command &> file
Overlaid manner, and outputs the correct transmission errors
That are saved to a file with them.
Commands & file >>
In an additional manner, the correct output, and error output
That are saved to a file with them.
Command >> file 12 >> file 2
The correct output is appended to the file 1, the wrong
Errors in the output 2 is added to the file.
4: command execution
Multi-character format command role.
; Command 1; 2 command plurality of commands executed sequentially, there is no link between the command.
&& command && command 2 1
When properly executed command 1 ($? = 0), the command will be executed 2.
1 When the command execution is incorrect ($? ≠ 0), the command will not be executed 2.
|| 1 || command Command 2
1 When the command execution is incorrect ($? ≠ 0), the command will be executed 2.
When the command is executed correctly 1 ($? = 0), the command will not be executed 2.