32. Linux Shell, common knowledge points

1. ChildProgramOnly the environment variables of the parent program will be inherited, And the subroutine will not inheritDefinitionVariable.

Custom variables: declare them as environment variables through export

Convert environment variables to custom Variables: Declare

Environment Variable = global variable

Custom variable = region variable

2. Read [-pt] variable

Options and parameters:

-P: Followed by a prompt character!

-T: the number of seconds that can be followed !』 This is interesting ~ Will not wait for the user all the time!

Read-P "input name:"-T 30 name

3. ulimit [2]

Ulimit-Get and set user limits

4 ,~ /. Bash_history records historical commands

[Root @ WWW ~] #! Number

[Root @ WWW ~] #! Command

[Root @ WWW ~] #!!

Options and parameters:

Number: indicates the number of commands executed;

Command: the nearest command searches for the command starting with "command" and executes the command;

!! : Execute the previous command (equivalent to pressing enter after pressing the keys)

5,Profile

①/Etc/profile: This is the overall setting of the system. You 'd better not modify this file;

②~ /. Bash_profile or ~ /. Bash_login or ~ /. Profile: the profile is set by the user. If you want to modify your own data, write it here!

Reference

[1]Http://blog.163.com/zhoumhan_0351/blog/static/39954227201061411191729/

Http://blog.163.com/zhoumhan_0351/blog/static/399542272010533254171/

Http://blog.163.com/zhoumhan_0351/blog/static/39954227201061045630711/

[2]Http://linux.vbird.org/linux_basic/0320bash.php#bash_bash