Shell script learning-4 (* assignment result)

Let's take a look at the asterisk assignment:

 

[Rocrocket @ rocrocket ~] $ Myvar = *

[Rocrocket @ rocrocket ~] $ Echo $ myvar
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-- The original * will be automatically replaced with the file list in the current directory.

 

In fact, the idea above cannot let us fully understand the essence. This is a shell knowledge point. Let us know.

Shell does not replace the file name when assigning values to variables. So when you execute x = *, only an asterisk is assigned to the X variable. The actual replacement occurs in Echo $ X.

The detailed steps are as follows:

1. When x = * is executed, shell scans the command line and assigns * to X.

2. When Echo $ X is executed, shell replaces $ X *

3. Shell replaces * with the file list in the current directory.

4 shell executes the echo command to pass the file list as a parameter to it.

This is the procedure. It is not difficult to remember: "variables are not replaced by matching values. Shell replaces variables first, file names, and finally processes parameters ".