11th chapter, Understanding and learning the operating environment of Bash Bash Shell

The operating environment of the Bash Shell:

Configuration values are divided into the overall system configuration values and preferences of each person, only some files placed in different places!

Path and command search order

When a command (such as LS) is released, which LS is it running?

1. Run the command in a relative/absolute path, such as "/bin/ls" or "./ls";
2. Run by alias to find the command;
3. Run by Bash built-in (BUILTIN) command;
4. Run through the first command that is searched $PATH the order of this variable.

It can be found that LS has color but/bin/ls has no color. Because/bin/ls is used directly with the command, and LS uses the command alias "Alias ls= ' ls--color=auto '!"

If you want to know the order of command search, you can enter type-a ls to query

[Email protected] jdk1. 7 ls ls is aliased to 'ls --color=auto'ls is/bin/ls

Examples:

Configure Echo's command alias to become echo-n, and then observe the order of Echo run

For:

[Email protected] jdk1. 7 Echo Echo is aliased to 'Echo -e'echo is a shell builtinEcho is/bin/Echo

Bash's pit stop and welcome message:/etc/issue,/ETC/MOTD

When the terminal interface (tty1 ~ tty6) Landing, there will be a few lines of prompt string

This information is written in/etc/issue

 more/etc/6.4  (Final) Kernel \ r on an \m

The meaning of each code within the issue

\d the date of the local end time; \l Display the first terminal interface; \m Display hardware level (i386/i486/i586/i686 ...) ； \ n Displays the network name of the host; \o display domain name; \ r operating system version (equivalent to uname-r) \ t Displays the time of the local end time; The name of the \s operating system; The version of the \v operating system.

11th chapter, Understanding and learning the operating environment of Bash Bash Shell