A simple example of LinuxShell Programming

A simple example of LinuxShell programming-Linux general technology-Linux programming and kernel information. The following is a detailed description. Introduction: I have been learning shell for some time. I feel that learning shell is a multi-practice program like other languages. A lot of online shell beginners are worried that they will not be able to find the practice program. I have integrated some basic exercises I encountered during shell learning, hoping to inspire shell beginners. (Maybe it shouldn't be integration. I'm used to this word)

There is no order in the example: Each example may have multiple methods
1.
Search for all files containing codfei in/home/codfei and its subdirectories.

Method 1:
[Root @ localhost Linuxos] # grep-rsn "codfei"/home/
/Home/codfei/c/Unix_c/2: 1: codfei ::::::::::::::::::::::
/Home/codfei/c/Unix_c/1: 1: codfei ::::::::::::::::::::::
Binary file/home/codfei/c/. charset. c. swp matches

Method 2:
[Root @ localhost Unix_c] # find/home/codfei/-type f | while read I; do grep-n codfei $ I & echo -----; done
1: codfei ::::::::::::::::::::::
/Home/codfei/c/Unix_c/2
-----
1: codfei ::::::::::::::::::::::
/Home/codfei/c/Unix_c/1
-----
Binary file/home/codfei/c/. charset. c. swp matches
/Home/codfei/c/. charset. c. swp
-----

2. Design a Shell program and create 50 directories under the/userdata directory, that is, user1 ~ User50, and set the permission for each directory to rwxr-xr --

Method 1:

#! /Bin/bash

# The simplest and most efficient method

Mkdir-p/userdata/{1 .. 50} & chmod 754/userdata/{1 .. 50}


Method 2:

#! /Bin/bash

# Use the seq command to add the while read Structure

Seq 1 50 | while read I; do
Mkdir-p/userdata/$ I
Chmod 754/userdata/$ I
Done


Method 3:

Use for or while loop

#! /Bin/bash

I = 0
While [$ I-lt 50]; do
Let I = I + 1
Mkdir-p/userdata/$ I
Chmod 754/userdata/$ I
Done



#! /Bin/bash

For (I = 1; I <= 50; I ++); do
Mkdir-p/userdata/$ I
Chmod 754/userdata/$ I
Done

Method 4:

#! /Bin/sh


For D in user {1 .. 50}
Do
Mkdir-m 754-p $ D
Done

3.

There is a file named abc.txt in the linuxsystem. How can I append the current system time to the beginning of this file line?

Three methods:

Echo-e "'date' \ n' cat ABC.txt '"> ABC.txt
Echo "'date | cat-ABC.txt '"> ABC.txt
Sed-I "1i 'date'" ABC.txt