Bash Tips And Tricks

Send Graphical Notifications To Your Screen

Using notify-send, you can send brief notifications to your screen. Useful for polling web information or if your writing a script and at the end you want the user to know it has completed

First make sure you have the software you need sudo apt-get install libnotify-bin

To send a message type in a console: notify-send "THIS IS A NOTIFICATION"

Instead of plain test you can notify the output of a command by enclosing your command like this: notify-send "`uptime`"

Common Options are:

-t (Time in milliseconds to show the notification)
-u [low/normal/critical] (Set the urgency level)
-i (Set a specific icon to show with the notification)

Making Bash Scripts and Outputs More Visually Appealing

As part of all linux OS's tput is a neat tool to make scripts and output messages with. You can control where the cursor is, color of text, style of text and generally give a little pizzaz to bash scripts that require user input. Ill just do a simple menu based script and put enough comments inline to give you a rough idea.

#! /bin/sh # clear the screen of all information tput clear # Move cursor to screen 5 lines down 10 characters indent (top left corner of your console is 0 0) tput cup 3 15 # Set the font colour using ANSI escape tput setaf 3 echo "Linux Wolf Pack" #Set font back to normal tput sgr0 #Positioning curser down and inward for menu items tput cup 5 15 # Set reverse video mode so that the title will stand out tput rev echo "M A I N M E N U" #Set font back to normal tput sgr0 #Make the menu user choices tput cup 7 17 echo "1. Make a backup" tput cup 8 17 echo "2. Restore a backup" # Set font to bold tput bold #Position user input position tput cup 10 15 read -p "Enter your choice [1-2] " choice #Clear the screen tput clear #Return text to normal tput sgr0 tput rc echo "You entered $choice"

Dialog The Ultimate BASH GUI

I love the console and running command line interfaces and commands. And the nicer you can make an interface the easier it is for a user to use it. Tput example above helps with basics but when it comes to more full looking scripts you might want to switch to dialog. There is every input and output form you can imagine available to view all option run man dialog in a console. You can use the little script I have done below as a quick guide.

#!/bin/bash #set screen title to linuxwolfpack test then prompt the user for a yes/no answer dialog --title "Delete file" \ --backtitle "linuxwolfpack test" \ --yesno "Do you want to run the backup?" 7 60 # What the picks will determine the numeric returned # 0 means yes # 1 means no # 255 means they hit ESC key #Get the users selection response=$? #Perform an action depending on what they chose case $response in 0) dialog --msgbox "Running Backup" 10 20;; 1) dialog --msgbox "Not Running Backup" 10 20;; 255) echo "Nothing Selected...You canceled the script";; esac

Logging Output To System Log

While working on scripts its good to output errors and sometimes sucess messages to the main system log. This can easily be accomplished with the "logger" command. Simply add the command

logger MESSAGE_TO_ADD

to your script file to have MESSAGE_TO_ADD added to /var/log/syslog. You can add a -t and a name to the command to specify the program. This makes it easier to look for messages just for that program in case something goes wrong. For instance if your writing a backup script you might want to use:

logger -t BACKUP "Backup for system failed"

Now if you need to look at any output logs from your backups you can grep BACKUP /var/log/syslog and all instanced will show.