5. This simple "echo" usage, can the child next door!

One , Common options

• echo -n Indicates no line feed output
• echo -e Output escape character , Output the escaped content to the screen

Two , Commonly used escape characters

\b After escape, it is equivalent to pressing backspace key (backspace) , But the premise is "\b" There is a character after ; “\b" It means to delete the first one characters ,”\b\b" Indicates deletion of the first two characters

\c Don't wrap output , stay "\c" If there are no characters after , The effect is equivalent to echo -n; But when "\c" When characters still exist after ,"\c" The following characters will not be output

\n Line break , The character to be output is from "\n" Start a new line

\f Line break , But the beginning of the new line after the newline is connected to the end of the previous line

\v And \f identical

\t Insert after turn tab, That is, the horizontal tab

\r Move the cursor to the beginning of the line , But don't wrap , It is equivalent to using "\r" Later characters overwrite "\r" Characters of the same length before : But when "\r" When there are no characters after ,"\r" The preceding characters will not be overwritten

\ Indicates insertion "" In itself

i=`echo "11,22,33,44"`
echo ${i%,*}
11,22,33
// From the last countdown to the shortest matching part ( use %) The following comma is deleted 

echo ${i%%,*}
11
// From the last countdown to the longest matching part ( use %%) The following commas are deleted 

echo ${i#*,}
22,33,44
// From the beginning to the shortest matching part ( use #) The following comma is deleted 

echo ${i##*, }
44
// From the beginning to the longest matching part ( use ##) The following comma is deleted 

3、 ... and 、 Use echo Command print special effect text

• echo Output the content of the specified color
• usage ： Need to combine -e Options and “\033” Use it together
• Format ：echo –e “\033[ Foreground color ; The background color m character string \033[0m”

notes ： The position of foreground color and background color can be interchanged

 Insert the code slice foreground color here ：30m-37m

 black ：echo -e “\033[30m  Black lettering  \033[0m”

 Red ：echo -e “\033[31m  Red character  \033[0m”

 green ：echo -e “\033[32m  The green word  \033[0m”

×××：echo -e “\033[33m ××× word  \033[0m”

 Blue ：echo -e “\033[34m  Blue words  \033[0m”

 violet ：echo -e “\033[35m  Purple words  \033[0m”

 Sky blue ：echo -e “\033[36m  Sky blue  \033[0m”

 white ：echo -e “\033[37m  White words  \033[0m”

 The background color ：40m-47m

 black ：echo -e “\033[40m  Black base  \033[0m”

 Red ：echo -e “\033[41m  Red background  \033[0m”

 green ：echo -e “\033[42m  Green bottom  \033[0m”

×××：echo -e “\033[43m ××× At the end of  \033[0m”

 Blue ：echo -e “\033[44m  blue ground  \033[0m”

 violet ：echo -e “\033[45m  Purple background  \033[0m”

 Sky blue ：echo -e “\033[46m  The sky is blue  \033[0m”

 white ：echo -e “\033[47m  White background  \033[0m”

• Description of control options

\033[0m  Turn off all properties 

\033[1m  Set high brightness 

\033[4m  Underline 

\033[5m  flashing 

\033[7m  Reflexion 

\033[8m  Blanking 

\033[30m — \33[37m  The foreground 

\033[40m — \33[47m  Background color 

\033[nA  The cursor moves up n That's ok 

\033[nB  The cursor moves down n That's ok 

\033[nC  The cursor moves right n That's ok 

\033[nD  The cursor moves left n That's ok 

\033[y;xH Set cursor position 

\033[2J  Clear the screen 

\033[K  Clear the contents from the cursor to the end of the line 

\033[s  Save cursor position 

\033[u  Restore cursor position 

\033[?25l  hide cursor 

\033[?25h  Show cursor 

n That's ok

\033[y;xH Set cursor position

\033[2J Clear the screen

\033[K Clear the contents from the cursor to the end of the line

\033[s Save cursor position

\033[u Restore cursor position

\033[?25l hide cursor

\033[?25h Show cursor