Linux character in command

*    matches zeor or more characters 

?    matches any single character

[a-z]    matches a range of characters

Example: text[1-2].txt

[^a-z]    matches all except the range

Example: text[^1-2].txt

 

cd ~<username>: go to the home directory of the user(only can be applied by root)

cd ~: go to the home directory of current user

 

use {} in command

Example:

#touch {a,b}

the command will create a,b two files

#touch a{a,b}

the command will create aa,ab two files

#touch {a,b}.{1,2}

the command will create a.1,a.2,b.1,b.2 four files

 

Comand inside another command

Example:

#echo "Hostname:`hostname`" or echo "Hostname:$(hostname)"

 

Variable Math in command

Example:

#a=3

#echo $a

3

#b=5

#echo $b

5

#echo $[ $a + $b ]

8

#echo $[ $a ** $b ] (**: ^)

243

 

Variable change to normal string: \ or double quote "" or single quote''

Example:

#echo "Your cost is \$5.00"

Your cost is $5.00

Exception

double quote no use for $, \, `, !

 

\: use to input command in next line

Example

#ls \

>-l