A script that takes you through the Shell basics

For example, the need to test a batch of IP in the work is still blocked, you need to write a simple script ping test.

We need two machines,

Virtual Host: centos6.7 system

Local linux:centos6.5

"Virtual Host"

Remote to the host, add IP (Learn the script, let me show off a bit)

You can use Xshell to do the following

Of course if you save with a Windows text file, you might add a failure because: Windows and Linux line breaks are not the same

And there's No "^m" edited in Linux.

You can use: sed command to deal with a bit like:

Sed ' s/^m//g ' troubles.txt >testip.txt #linux中 ^m Input Method: Ctrl + v +m

If you do not trust can be executed: cat-a testip.txt # haha, no ^m.

Execute small script to add IP: SH addip.sh # occasionally used, no need to add "execute permission"

IP Addr # view IP

"Local Linux"

Same upload trouble.txt, same fallback ^m for processing

You can also remotely copy it here:

SCP testip.txt [email protected] # hehe, intranet IP, external network can not access, forget it!!!

Ping script:

SH ipping.sh

Shell programming

The shell interprets the input to the operating system by prompting you for input.

Here with/bin/bash
Echo $SHELL

The format is as follows
#!/bin/bash# fixed format, in the first line of each script

System variables

Env #命令行输入 View

Environment variables

$HOME the current user's logon subdirectory
$PATH a colon-delimited list of subdirectories to search for
$PS 1 command-line prompt, usually a "$" character
$PS 2 Secondary prompt to prompt for subsequent input, usually ">" Characters
$IFS the delimiter for the input area. When the shell reads the input data, it considers a set of characters as separate characters between the words, usually spaces, tabs, and line breaks
$0shell the name of the script program
$# is the number of arguments passed to the script, $ #是一个数字

$* shows all parameters passed to the script, $* is a string

$? is to display the exit status of the last command, 0 means no error, others indicate an error
$$ the shell script's process ID, which is typically used by the scripting program to create unique temporary files, such as/tmp/tmpfile_$$

A first variable. The corresponding $ A is the second variable, and so on.
$UID the ID of the current user
$PWD

Custom variables (a class of character combinations that start with a letter or underscore , preferably known as a name )

In addition to system variables, others can be used,
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In a shell script, if is also often judged about the file attributes, such as whether it is a normal file or a directory, to determine if the files have read and write execution rights. There are several options that are commonly used:

-E: Determine if a file or directory exists

-D: Determine if the directory is not present and whether it exists

-F: Determine if the file is normal and exists

-R: Determine if the document has Read permissions

-W: Determine if Write permission is available

-X: Determine if executable

When you use the If judgment, the specific format is:
If [-e filename]; Then
echo "FileName exists"
Else
echo "No This file"

Fi
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First of all, the actual combat in the refining after the addition, please give more advice, more praise, thank you

A script that takes you through the Shell basics