How to get input from the user in Bash?

How to get input from the user in Bash?

So we now have 3 methods for getting input from the user: 1 Command line arguments 2 Read input during script execution 3 Accept data that has been redirected into the Bash script via STDIN

Can you add a GUI to a bash script?

But if it is used by a general audience it is obviously good to have some user friendly interactions. In fact, you are able to include GUI (Graphical User Interface) based input/output components into your next bash script using the Zenity command line tool which helps us to display GTK dialog boxes.

How to create a script for user input?

Let’s dabble with input. Create a simple script which will ask the user for a few pieces of information then combine this into a message which is echo’d to the screen. Add to the previous script to add in some data coming from command line arguments and maybe some of the other system variables.

When to use command line arguments in Bash?

You should normally favor command line arguments wherever possible. They are the most convenient for users as the data will be stored in their command history so they can easily return to it. It is also the best approach if your script may be called by other scripts or processes (eg. maybe you want it to run periodically using CRON).

When to use shift with input arguments in Bash?

If your input arguments don’t expect a value then a shift is required near the end of the loop only. If you have a requirement to only collect 2-3 input arguments you can avoid shift if it feels too complicated for you. In this example we will use case statement with while loop to check for input arguments.

How to deal with errors in bash script?

Bash Error Handling Tip #1: Exit on Errors in Bash When you encounter an error in a bash script, by default, it throws an error message to stderr, but continues its execution in the rest of the script. In fact you see the same behavior in a terminal window; even if you type a wrong command by accident, it will not kill your terminal.

How to use if condition in bash script?

In this example we will use if condition to parse the input arguments and perform respective action. Here I have written a small script which is expected to collect following input arguments Line 3 to Line 12 are my usage function which should be clear enough.

What’s the best way to make a script in Bash?

This is where scripting becomes your salvation. To see what is meant by scripting, use shell in combination with your favorite text editor eg. vi to create a new file called task.sh containing all the above commands, each on a separate line. Once ready, make your new file executable using chmod command with an option +x.

How to write data to a text file in Bash?

To write data to a text file from a Bash script, use output/error redirection with the > and >> redirection operators. > Overwrites data in a text file. >> Appends data to a text file. Creating a basic script and understanding the redirection

Can you use arguments in a bash script?

Arguments can be useful, especially with Bash! So far, you have learned how to use variables to make your bash scripts dynamic and generic, so it is responsive to various data and different user input. In this tutorial, you will learn how you can pass variables to a bash scripts from the command line.

How to prompt for yes / no / cancel input in a Linux shell?

I want to pause input in a shell script, and prompt the user for choices. The standard Yes, No, or Cancel type question. How do I accomplish this in a typical bash prompt? The simplest and most widely available method to get user input at a shell prompt is the read command. The best way to illustrate its use is a simple demonstration:

Is it possible to change user within shell script?

It’s not possible to change user within a shell script. Workarounds using sudo described in other answers are probably your best bet. If you’re mad enough to run perl scripts as root, you can do this with the $< $ ( $> $) variables which hold real/effective uid/gid, e.g.:

How to prompt for yes or no in Bash?

You can use the built-in read command ; Use the -p option to prompt the user with a question. Since BASH4, you can now use -i to suggest an answer : (But remember to use the “readline” option -e to allow line editing with arrow keys) If you want a “yes / no” logic, you can do something like this: read -e -p ” List the content of your home dir ?

How to modify a config file using BASH script?

I’m writing a bash script to modify a config file which contains a bunch of key/value pairs. How can I read the key and find the value and possibly modify it?

How to send all keys to all panes in tmux?

This allows me to run tmux send-keys-all-panes or tmux skap to all panes. Note that tmux is aliased to my wrapper function tmux_pp. Quick illustration on how to configure your own binding for synchronize panes. Added the following into my tmux.conf (the comments certainly apply to my overall configuration):

Which is the best way to get input from the user?

So we now have 3 methods for getting input from the user: Which method is best depends on the situation. You should normally favor command line arguments wherever possible. They are the most convenient for users as the data will be stored in their command history so they can easily return to it.

How to check the input is numeric in Bash?

The problem I have is if the user types a letter or a space by mistake, the whole script fails and the user must start again. There must be an easy way to check the input is numeric only that will ask for the input again if anything else is input accidentally? if [ [ ! $input || $input = * [^0-9]* ]]; then echo “Error: ‘$input’ is not a number.”

Is there a problem with the bash script?

I wrote a bash script which takes numbers for calculation via user input. The problem I have is if the user types a letter or a space by mistake, the whole script fails and the user must start again.

How to send a message from a bash script?

You can use this curl command from inside a bash script, and you can configure the JSON object to send whatever data you’d like, including from bash variables. The message API can do more than just send simple text. If you’d like your messages to be more stylized, you’ll have to add some extra parameters to the JSON object that curl sends out.

How to send notification or alert when Bash asks for something?

There is an alias in my .bashrc which uses notify-send: I can append alert to other commands as somecommand; alert or somecommand && alert and get get a pop-up notification after somecommand finishes (successfully). It reminds me that the command I ran in a Terminal window which is now minimised or in a different workspace has finished executing.

How to create a bash script in Windows?

This will read whatever is entered by the keyboard and save it to the variable. To start, create a new bash script named input.sh: Add the following lines. These commands will display a question, take input from the user, and print the value entered while also combining it with a string.

How to assign a variable to a filename in Bash?

Variable assignments don’t take the $ notation in bash shell. You just need below without the $ And later in the script if filename is a variable and trying to construct a name with .o appended, enclose the variable name within {} , so that the variable is expanded properly

How to extract file name and extension in Bash?

You can use it for manipulating and/or expanding variables on demands without using external commands such as cut, tr, sed or awk. The syntax is as follows to remove the pattern (front of $VAR): To get file name, enter: The syntax is as follows to remove the pattern from back of $VAR:

How to read input from a Unix file?

You can use sed, cut and many other unix utilities like in examples. Chose of utility depends on how you need to transform input data. Of course you can change examples as you want. Not the answer you’re looking for?