AIX System Shell Programming Basics

What is a shell?

The Shell is an interface between the operating system and the user that interprets the commands the user emits, launches the application, and manages the user data with system features. The shell can run multiple processes simultaneously in the foreground or in the background under the user's interactive control, and the shell is also an effective programming language.

1. Wildcard characters

(1) *: multiple arbitrary characters

$ ls

Info Newdir test.file testfile

mbox newtest.file Test1.file Wangyi

$ ls *.*

Newtest.file Test.file Test1.file

(2)?: Single arbitrary character

$ ls????. *

Test.file

(3) []: a single character between []

$ ls [mt]*

Mbox Test.file Test1.file

(4) [-]: a single character in the [-] range

$ ls [m-w]*

mbox newtest.file test.file test1.file testfile

Newdir:

Wangyi:

(5)!: not one or some characters

$ ls [!t]*

Mbox Newtest.file

Info

Notes TMP

Newdir:

Wangyi:

Test.file

2. Standard input and output

In the AIX standard state, the input comes from the keyboard, the output is to the screen, and the error message is displayed on the screen.

REDIRECT Symbol system variable name

Standard input < (<<) 0

Standard output > (>>) 1

Standard error Output 2> (2>>) 2

3/redirect

In AIX environments, standard input, output, and error messages can be redirected, allowing users to get input from places other than the keyboard (such as files, serial ports, etc.) and send the input and error messages to other places (such as files, etc.) outside the screen.

Input redirection

$ command < filename

$ Mail Xumin < Test.file

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