Two ways to shell command substitution _linux Shell

Command substitution means that the Shell executes a command and replaces the command substitution with the result of executing the command.

There are two ways to replace a command:

1. Use backtick symbols (i.e. ..., inverted quotes, accented symbols).

Copy Code code as follows:

For i in ' cd/old/code/dir; Echo *.c '
Todo
Diff-c/old/code/dir/$i $i | More
Done

2. Use the $ (...) method.

Copy Code code as follows:

For I in $ (cd/old/code/dir echo *.c)
Todo
Diff-c/old/code/dir/$i $i
Done | More

Note: When using the first method, the embedded Backtick symbol and double quotation mark need to be escaped. In the second way, the inline parentheses do not need to be escaped.