Common shell programming and instances-continuous updating

This article by larrylgq prepared, reproduced please note the Source: http://blog.csdn.net/larrylgq/article/details/7395261

Author: Lu guiqiang

Email: larry.lv.word@gmail.com

Variable:
AAA = "LV"; do not use Spaces
Echo $ AAA-> LV
Echo $ {AAA} TXT-> lvtxt
Echo export aaa.txt-> lv.txt

Evaluate:
A = 1
B = 2

1: Let:
Let C = a + B
Echo $ C
3

2: $ []:
D = $ [A + B]
Echo $ d
3

3: $ (()):
E = $ (a + B ))
Echo $ E
3

Condition determination:

1: Numerical judgment:
-Ne-lt-lessthan-GT-le
If [$ A-GT 0]; then
> Echo hahaha
> Fi
Hahaha

2: String judgment:
A = A1
B = b1
If [[$ A = $ B]; then
! = <=>=-Z (whether it is empty)-N (whether it is not empty)
> Echo test
> Else echo OK
> Fi
OK
3: Others
If [[-N $ B]; then echo test; else echo OK; FI
-N is null
-F indicates whether to file
-D: directory?
-X executable?
-E exists?
-W is writable?
-R readable?
-L link?
If [-f lv]; Then ECHO yes; else echo no; FI
If [-d lv]; Then ECHO yes; else echo no; FI
A = zookeeper
If [-F $ A]; Then ECHO yes; else echo no; FI
Yes

Note: [] must contain spaces.

Loop:

1: For (I = 0; I <100; I ++) {echo $ I ;}
A space is required before echo.
2: For (I = 0; I <100; I ++); Do echo $ I; done

3: for I in {1 .. 100}; do echo $ I; done

4: Echo {1 .. 100}
Echo {A. z}
; No line feed is returned.

5: Create 1. Text and enter a number in 1. Text.
For I in 'cat 1.txt '; do echo $ I; done

Practice 1:Copy202.csv to the root@192.168.1.208 :~ /Change the name to 201-220 respectively, and then delete

For (I = 1; I <10; I ++); Do SCP 2.csv root@192.168.1.208 :~ /20ii.csv; done
For (I = 10; I <= 20; I ++); Do SCP 2.csv root@192.168.1.208 :~ /22.16i.csv; done
Or
For (I = 1; I <= 20; I ++); do if [[$ I-lt 10]; then SCP 2.csv root@192.168.1.208 :~ /N20ii.csv; else SCP 2.csv root@192.168.1.208 :~ /N2w. I .csv; FI; done

SSH root@192.168.1.208
For (I = 1; I <= 20; I ++); do if [[$ I-lt 10]; then RM ~ /20ii.csv; else RM ~ /22.16i.csv; FI; done