The difference between single quotes, double quotes, and anti-quotes in Linux

1.single and double quotation marks are used for the user to assign a string with a space to the delimiter of the variable.

[email protected] sh]# str= "Today is Monday"
[email protected] sh]# echo $str
Today is Monday
If there is no single or double quotation marks, the shell interprets the string after the space as a command.
[email protected] sh]# Str=today is Monday
Bash:is:command not found

2, the difference between single and double quotation marks. Single quotes tell the shell to ignore all special characters, while double quotes ignore most but do not include $ \ '

The ' $ ' (parameter substitution) and ' ' ' (command substitution) are exceptions in double quotes, so there's basically no difference between the two, unless the parameter substitution $ and the command substitution are encountered in the content.

such as: num=3

Echo ' $num '

$num

echo "$num"
3
Therefore, if you need to use both symbols in the double quotation mark "", you need to escape with a backslash.

3.The back quotation marks (') are located above the TAB key of the keyboard and the left side of the 1 key. Note the difference between the single quotation mark (') on the left side of the ENTER key. plays the role of command substitution in Linux. Command substitution refers to the ability of the shell to interpolate the standard output of a command anywhere on a command line.
For example, the shell executes the date command in an inverted quotation mark and inserts the result into the content displayed by the echo command.
[email protected] sh]# echo the date is ' date '
The date is Monday, March 14, 2011 21:15:43 CST

The difference between single quotes, double quotes, and anti-quotes in Linux