The shell must read at first, it is highly recommended for beginners to read

Background:

A lot of people have been converted from C + +, after reading the study document, stepping into a lot of pits

1 assigning values to variables don't have spaces

# correct a = 123    #  error

2 if statement [] to leave a space, the variable is best to add ""

if " $a "-eq"  #  pair if [$a-eq]      #  wrong

3 in many cases want to output "! "This is a time to use single quotes

Echo ' ok! '        #对的echo "error!"  # of the wrong

4 position parameter more than 10 to use the curly braces less than 10 can not

Echo ${10}     # is correct, indicating that the 10th variable is printed echo $         # is also correct, but represents the first variable followed by a 0

5 Remember that uninitialized variables are null, not 0

6 double quotes in an if statement

if " $a " ]        #  Right if [-N $a]           # Error

7 Child shell operations do not affect the parent shell

Child Shell:

# !/bin/bash string_test="TEST"export string_test

Parent Shell:

Echo $STRING _test

8 DOS-style \ r \ n is not legal in bash

Dos2unix need to convert

9 spaces appear in parameter passing

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The shell must read at first, it is highly recommended for beginners to read