Marco Linux Learning Notes (bash variable configuration)

Bash : Interpreter, compiler

configuration file, the scope of effective, there are two categories:

Global configuration:

/etc/profile,/etc/profile.d/*.sh

/etc/bashrc

Personal configuration:

~/.bash_profile

~/.bashrc

By function, there are two categories:

Profile classes: For interactive logins Shell Provide configuration

/etc/profile,/etc/profile.d/*.sh

~/.bash_profile

Function:

(1) Define environment variables, such as PATH,PS1

(2) Run a command or script

BASHRC class: For non-interactive logins Shell Provide configuration

/etc/bashrc

~/.bashrc

Function:

(1) define command aliases;

(2) define local variables;

Variables: Memory space, variable name

Type:

Environment variables: scope Current Shell process and its child processes

Local Variables: scope current Shell Process

Local Variables: The scope is only the current Shell a piece of code in the process ( typically a function context )

How variables are defined:

Bash built-in variables: can be called directly, built in a number of environment variables, such as PATH wait

Custom variables:

variable Assignment: variable name = value

Bash Weak type:

When a variable stores data, it is written by default, and any variable can be directly referenced without being declared;

- : 24bits

120:8bits

To define a local variable:

Name=value

View: Set

Define Environment variables:

Export Name=value

Declare-x Name=value

View: env, printenv, export

Undo Variable:

unset name

Reference variable:

${name}, $name

Bash the reference symbol in:

"': strong references, variable substitution does not occur

"" : Weak references

``: Command Reference

Shell Login Type:

Interactive login:

Login directly through the terminal;

through su-l Username User Switching of the command implementation;

Non-interactive logon:

A command-line window opens under the graphical interface;

Execute the script;

Su Username;

Configuration file Action Order:

Interactive login:

/etc/profile-->/etc/profile.d/*.sh---~/.bash_profile, ~/.BASHRC--/ETC/BASHRC

Non-interactive logon:

~/.BASHRC-->/ETC/BASHRC--/etc/profile.d/*.sh

How does the new configuration of the Edit profile definition take effect?

(1) re- login;

(2) let the current Shell process to re-read the specified configuration file;

Source/path/to/somefile

. /path/to/somefile

Note: Side effects

Marco Linux Learning Notes (bash variable configuration)