A comparison of Shell and other languages
1. The main functions of php and java
2. Shell simplifies management operations
two what is a variable
Three-variable naming convention
Four variables are classified according to stored data
string
Integer
floating point
date type
Shell stores all strings
Classification of five shell variables
1. User-defined variables. Variable customization.
2. Environment variables: This variable mainly stores data related to the operating environment of the system. Variables can be customized, but the variable names and variable functions that take effect in the system environment are fixed.
3. Positional parameter variable: This variable is mainly used to pass parameters and data to the script. The variable name cannot be customized, and the function of the variable is fixed.
4. Predefined variable: It is a variable that has been defined in Bash. The variable name cannot be customized, and the function of the variable is fixed.