Control the output color of the shell script _linux shell

Implementation code:

#!/bin/sh

# ANSI Color-Use this variables to make output in different colors
# and formats. Color names that end with the ' F ' are foreground (text) colors, # and those ending with
' B ' are background.

Initializeansi ()
{
 esc= "\033" # if this doesn ' t work, enter an ESC directly

 blackf= ' ${esc}[30m ';  Redf= "${esc}[31m";  greenf= "${esc}[32m"
 yellowf= "${esc}[33m"  bluef= "${esc}[34m";  purplef= "${esc}[35m"
 cyanf= "${esc}[36m";  whitef= "${esc}[37m"

 blackb= "${esc}[40m";  redb= "${esc}[41m";  greenb= "${esc}[42m"
 yellowb= "${esc}[43m"  blueb= "${esc}[44m";  purpleb= "${esc}[45m"
 cyanb= "${esc}[46m";  whiteb= "${esc}[47m"

 boldon= "${esc}[1m";  boldoff= "${esc}[22m"
 italicson= "${esc}[3m"; italicsoff= "${esc}[23m" ulon= "${esc}[4m"
 ;   uloff= "${esc}[24m"
 invon= "${esc}[7m";   invoff= "${esc}[27m"

 reset= "${esc}[0m"
}

Define the function first, then initialize the next function, and then you can see the effect.
Perform

Echo-e ${yellowf}this is a phrase in Yellow${redb} and Red${reset}
Echo-e ${boldon}this is Bold${ulon} it is italics${reset} bye bye
Echo-e ${italicson}this are Italics${italicsoff} and this isn't

After you know it, you can write a colorful, cool script.