Linux bash-Script Basics

Script execution:

The script starts a child shell process when it executes. Scripts that are started on the command line inherit the current shell environment variables, and the system-initiated scripts (not command-line launches) require a self-defined amount environment variable.

Program Status Return code:

0: Execute correctly.

1-255: Error execution, 1, 2, 127 system reserved.

Exit

• Role

Exits script execution, which defines the execution state of the script. If the script does not explicitly define the exit status code, then the exit code of the last command executed is the exit status code of the script.

Let

• Role

Represents an arithmetic operation.

$[] or $ (()) or expr an arithmetic operation expression (a space between the operands and operators in an expression and a command reference) can be used for arithmetic operations.

Linux bash-Script Basics