Using variables in sed command

stay sed There are three ways to use variables in commands

The way 1: Use single quotes , Use single quotation marks at variables + Double quotation marks enclose variables

#!/bin/bash
name=tomas
sed -i 's/rose/'"${name}"'/g' b.txt

The way 2: Use double quotes , Variables can be directly referenced

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#!/bin/bash
name=tomas
sed -i "s/rose/${name}/g" name.txt

The way 3: Use single quotes , Variables are directly referenced , But it needs to pass eval Execute this sed command .eval Will be right behind Shell Command to scan twice , If after the first scan ,Shell Command is a common command , Then execute this command ; If Shell Commands are indirect references that contain variables , Ensure the semantics of indirect reference

#!/bin/bash
name=tomas
eval sed -i 's/rose/${name}/g' name.txt