Advanced instruction

1.df instruction

function df command to view disk space:
grammar df command : # df-[-h]
df common parameters :
-h: expressed in the form of a high readability to read the display size of the disk # 1.df instruction

2.free instruction

free function instructions : for viewing memory usage
syntax free instructions : #Free [-m]
free common parameters :
-m: expressed in MB view

3.head instruction

head instruction function : document represents a front view how many lines
syntax head instruction : #head [-n] file path
head common parameters :
-n: is a view showing how many rows
Note: If the number n is not specified, the default Check that the first 10 lines of the file

4.tail instruction

head instruction function :
Function 1: a view showing a file last line
syntax : #tail [-n] file path
Note: not specified n, default view is the end line of this file 10
feature two: a view showing a file dynamically changing content, most of this command in conjunction with other command, usually used to view the system log
syntax : #tail -f file path

5.less instruction

function less directive : that view files, and files with less output
less command syntax : #less file path
Note: To see more of the contents, then press up and down arrow keys to press q to quit when

6.wc instruction

wc command function : the statistical information representing the contents file may be made statistics lines, number of words, the number of bytes of the file
syntax wc instructions : #wc [parameter] file path
wc common parameter table
1.-l: Statistics file the number of lines;
2.-d: number of words in the statistics file, it is a space to distinguish between words;
3.-c: byte counts files;

7.date instruction

function instruction date : indicates the date and time of operation (read, set)
date Instruction Syntax : #date [parameters]
date common parameter table
1.% F: indicates complete date;
2.% T: represents the complete when the minutes and seconds;
3.% the Y: represents a four-digit year;
4.% m: represents the two-month;
5. the% D: represents the date;
6. the% H: for hours;
7. the% m: denotes minutes;
8. % S: the number of seconds
Note: this command symbol has two options: "-" indicates before, "+" indicates after, such as access to a historical time #date "+% Y-% m-% d"

8.cal instruction

function cal instruction : that the operation of the calendar
cal command syntax :
Syntax 1 : #cal direct output current calendar month
Syntax 2 : #cal -3 + represents a month's calendar next month on month + output
Syntax 3 : #cal -y year represents the output of one calendar year

9.clear / ctrl + L instruction

Function : removes terminal operation information already present in the command
syntax : # clear or Ctrl + L

10. Pipeline

Pipe character : |
effect : pipes play a supporting role is mainly used for general ,, "filter", "Special", "expansion" is performed, it can only be used with other instructions for use

The desire to help people, most parameters are common ~~~~~~~~~~~~~~~~~~~~