Communications Commands Certain of the following commands find use in network data transfer and analysis, as well as in chasing spammers.
We are going to build a bash script that will send a message to a user who is logged into the Linux system.
For this simple shell script, only a few functions are required. Most of the required commands are common and have been covered in our series of shell scripting; you can review the previous posts.
First, we need to know who is logged in. This can be done using the who command which retrieves all logged in users.
To check any logged user message status, use the who command with -T option. Write Command The write command is used to send messages between users using the username and current terminal.
The user must be logged onto the terminal We will send a message to testuser user from my user likegeeks like this: When you hit Enter, you can start typing your message. I recommend you to review the post about signals and jobs. The receiver can recognize which user on which terminal sends the message.
EOF means that the message is finished. Creating The Send Script Before we create our shell script, we need to determine whether the user we want to send a message to him is currently logged on the system, this can be done using the who command to determine that.
The final output from the awk command is stored in the variable logged. Then we need to check the variable if it contains something or not:There are two primary ways to use the shell: interactively and by writing shell scripts. In the interactive mode, the user types a single command (or a short string of commands) and the result is printed out.; In shell scripting, the user types anything from a few lines to an entire program into a text editor, then executes the resulting text file as a shell script.
How to write shell script. Following steps are required to write shell script: (1) Use any editor like vi or mcedit to write shell script. (2) After writing shell script set execute permission for your script as follows.
The parameter /home/wwwroot/r-bridal.com or /home/username/public_html or /var/www/html is the web root folder where you host your website files. You MUST have write. This article is an extension of our First article Understand Linux Shell and Basic Shell Scripting – Part I, where we gave you a taste of Scripting, continuing that we won’t disappoint you in this article.
This Bash shell scripting guide is not a detailed study but a quick reference to the BASH syntax. So lets begin. The following example, although extremely simple, provides a useful introduction to creating and using shell scripts.
The script clears the monitor screen of all previous lines and then writes the text Good morning, world. on it.