* Simple Script test-create a file using date *

Imagine that my server has a database, and the data in the database is different every day. So when I back up the database, I want to back up the data every day to a different file name, in this way, the old data can be saved and not overwritten. Wow! Different file names! This is really a problem? Do I need to modify the script every day?

No! The daily "date" is not the same, so I can name the file like backup.2011-08-15.data. Isn't it possible to have a different file name every day? Haha! Indeed. How did you get this? That's the point! The following example shows how to create three empty files.Touch)
, The beginning of the file name is determined by the user input. if the user has entered filename, the current date is. I want to create these files on the previous day, yesterday, and today, that is, filename_20151113, filename_20151114, and filename_20151115. How can this problem be solved?

 

#! /Bin/bash
# Program creates three files, which named by user's input and date command.
# History:
Path =/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin :~ /Bin
Export path

#1. Ask the user to enter the file name and obtain the fileuser variable;
Echo-e "I will use 'touch' command to create 3 files." # purely display information
Read-P "Please input your filename:" fileuser # Prompt user input

#2. To prevent users from pressing enter at will, is there any configuration for the file name using the variable function?
Filename =$ {fileuser:-"FILENAME"} # Start to determine whether there is a configuration file name

#3. start to use the date command to obtain the required file name;
Date1 = $ (Date
-- Date = '2 Days ago '+ % Y % m % d)# Date of the previous two days
Date2 = $ (Date
-- Date = '1 days ago'+ % Y % m % d) # date of the previous day
Date3 = $ (date + % Y % m % d) # today's date
File1 =$ {filename }$ {date1} # Name of the configuration file in the following three rows
File2 =$ {filename }$ {date2}
File3 =$ {filename }$ {date3}

#4. Create a file name!
Touch "$ file1" # create a file in the following three lines
Touch "$ file2"
Touch "$ file3"

 

Test:

[Root @ sor_sys test] #Sh datefile. Sh
I will use 'touch' command to create 3 files.
Please input your filename: bakupmas
[Root @ sor_sys test] # ll
Total 12
-RW-r -- 1 Root 0 Aug 15 bakupmas20151120.13
-RW-r -- 1 Root 0 Aug 15 bakupmas20151120.14
-RW-r -- 1 Root 0 Aug 15 16:51
Bakupmas20151115
-RW-r -- 1 Root 1015 Aug 15 16:35 datefile. Sh
-RW-r -- 1 Root 248 Aug 15 echo-e.sh
-RW-r -- 1 Root 434 Aug 15 read-p.sh
[Root @ sor_sys test] #

++ ++

If you do not enter a carriage return, the file filename20151116 filename20151117filename20151118 will be generated?

Variable configuration methodSTR is not configured as a Null String. STR is configured as a non-null string.

VaR =$ {STR:-expr}Var = expr Var = $ Str

++ ++

The reason listed above can be explained:

If you enter a non-empty value, it indicates that STR has been set to a non-empty character, then VaR is $ Str

If you press enter directly, that is, enter an empty string, then var takes expr

In this case, do you understand?