12. Start the shell script

Objective

What the hell is a shell? Before this, we should understand the issue of file permissions

Body

1. Shell version

   Various versions:

Bourne Shell (SH), C Shell (CSH), and Korn Shell (Ksh)

And at present:

The common and CentOS default shell is bash (Bourne Again Shell)

Can be considered as the upgrade of SH, enhanced version.

Programmer-"Shell (various versions), graphical interface (think of it)-" operating system-"hardware

1. File permissions

1. View File Permissions Ls-l

2.1-Bit Description permissions

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Three three See

RWX represents both read and write execution.

Encounter-represents no such permission

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First bit: To distinguish between a file or a directory or another device

-Represents an ordinary file

D stands for the directory

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Second to fourth bit: User's permissions on the file owner

Fifth to seventh bit: Group User rights

Eighth to tenth bit: other users

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1. Change permissions

   There are three kinds of permissions for files in Linux

   R: Reading (read) Number 4

   W: Write number 2

   X: Execute (EXECUTE) Number 1

   RWX on behalf of the very cock right

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chmod 777 AA

chmod u+x file name//assign permission to owner X

+ Delegate Assignment permission-on behalf of DELETE permission

chmod g+x to group users

chmod O+x to other users

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You can also set permissions by numbers

Chmod u

1. Operation

1. Create a shell folder

mkdir Shell

2. Create a test.c source file

CD shell

Vim test.c

#include <stdio>

Int Main () {

???? printf ("hello\n");

???? return 0;

}

Gcc-o Test test.c

3. Create a single AA file

Vim AA

Echo "Hello Shell"

Echo $PATH

./test

4. Modify AA to be operational permission

chmod u+x

5. Running

./AA

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End

The shell script AA is writing a bunch of commands, files with executable permissions

12. Start the shell script