"Linux" Bird's Linux private cuisine basic study finishing (i)

recently, I have been writing PPC simulators and assemblers, also in the design. So the new look at "Bird's Linux private dishes", or a lot of commands are not familiar. I'm going to write a few blog notes down.

1. nl [-BNW] FileName: Add line number to print
Parameters:
- B: Specifies the way the line number is specified, mainly in two ways:
- B A: Indicates that the line number (similar to cat-n) is also listed, whether or not it is a blank line;
- B T: If there is a blank line, do not list the line number (the default) for the empty row.
- N: List the method of line number representation, there are three main kinds:
-N LN: The line number is displayed at the left of the screen;
- N RN: The line number is displayed on the very right of its own field and does not add 0;
- N RZ: The line number is displayed on the very right of its own field, plus 0.
-W: the number of digits occupied by the line number field.

2. More: One page, one page flip
Supported keys:
Space: Represents a page down;
Enter: represents scrolling down one line;
/string: Represents the keyword in this display to query down the "string";
: F: Displays the file name immediately and the number of rows currently displayed;
Q: The delegate immediately leaves more, no longer displays the contents of the file;
B or [ctrl]-b: Represents paging back, but is useful only for files and useless for pipelines.

3. Less: one page, one page flip
Supported keys:
Space: Flipping down one page;
[PageDown]: flipping down one page;
[PageUp]: Flip up one page;
/string: Queries the keyword "string" Down;
string: Query up the keyword "string";
N: Repeats the previous query (related to/or);
N: Reverse repeats the previous query (related to/or);
Q: Exit.

4. Head [-N number] FileName: Remove the previous lines
Parameters:
- N: followed by numbers, representing the number of rows to display;

5. Tail [-NF] FileName: Take back a few lines
Parameters:
- N: followed by numbers, representing the number of rows to display;
- F: Indicates continuous detection of the subsequent files, until the [ctrl]-c] is pressed to end the detection of tail.

6. od [-t TYPE] FileName: Lookup fee Plain text file
Parameters:
-T: followed by various types of output, for example:
A: Use the default characters to output;
C: Use ASCII characters to output;
D[size]: Use decimal to output, each integer occupies size bytes;
F[size]: Use floating point number to output, each integer occupies size bytes;
O[size]: Use octal to output, each integer occupies size bytes;
X[size]: Use hexadecimal to output, each integer occupies size bytes;

7. Touch [-ACDMT] FileName: Modify file time or create file
Parameters:
-A : Modify the access time;
- C: Modify the file time, if the file does not exist, do not create the file;
- D: You can follow the date you want to modify without the current date, or you can use the--date= "date or time";
- m: Modify Mtime only;
- T: the time after which you want to modify instead of the current time, in the format [YYMMDDHHMM].

8. Umask [-S]: File default Permissions
Parameters:
-S: viewed as symbol type.

9. chattr [+-=] [asacdistu] FileName: Set hidden properties of the file
Parameters:
+: Add a special parameter, the other existing parameters will not move;
-: The deletion of a particular parameter, the other existing parameters are not moving;
=: Only the parameters that follow are followed.
A: When you set the A property, the access time Atime will not be modified if you have access to this file. Avoids excessive access to the disk by a slow I/O machine;
S: The general file is written asynchronously to the disk, plus the parameter S, when you make any changes to the file, synchronization also into the disk;
A: After setting up a, this file can only add data, the deletion can not modify the data;
c: After setting C, the file is automatically compressed. Automatic decompression when reading, but in the storage, the first compressed after storage;
D: When the dump program is executed, the D attribute is set so that the file will not be backed up by dump;
I: So that the file can not be deleted, renamed, set up the connection is also unable to add data;
S: If the file is deleted, it will be completely deleted from the disk;
u: If the file is deleted, the data content is actually still on the disk, can be retrieved.

lsattr [-ADR] filename: Show file hidden Properties
Parameters:
-A: Displays the hidden properties of the file;
-D: If it is a directory, list the properties of the directory itself rather than the files within the directory;
-R: Listed together with the data in the catalogue.

which [-a] command: Looking for "execute" file
Parameters:
-A : Lists all directories that can be found in the path directory, not just the first found command name.

Whereis [-BMSU] FileName: Finding a specific file
Parameters:
- B: only binary files are searched;
-M: only find files under the manual path of the description file;
- S: Only source files are found;
-U: Find other special files that are not among the above three options.

locate [-ir] keyword: finding specific keywords
Parameters:
-I: Ignoring the difference in case;
- R: The display of the regular expression can be followed.