Sis (smart input source) enables less manual switch for native or OS input source (input method). A global mode: sis-global-respect-mode to respect buffer/mode by proper input source Respect start: start Emacs with specified language. Respect evil: switch to English when leaving evil insert mode.; Respect minibuffer: switch to English when enter minibuffer. Hold the Ctrl key, click your user account’s name in the left pane, and select “Advanced Options.” Click the “Login Shell” dropdown box and select “/bin/bash” to use Bash as your default shell or “/bin/zsh” to use Zsh as your default shell. Click “OK” to save your changes. Bash on macOS Is Still Outdated. All newly created user accounts in macOS Catalina will use zsh by default. Bash will still be available, but Apple is signaling that developers should start moving to zsh on macOS Mojave or earlier.

Macos Bash Prompt For Input With Default Password
Macos Bash Prompt For Input With Default Browser
Macos Bash Prompt For Input With Default Keyboard
Macos Bash Prompt For Input With Default Key
Macos Bash Script
Macos Bash Prompt For Input With Default Password
Macos Bash Prompt For Input With Default Key

1. Introduction

When we create Bash scripts, it can be handy to take user input. In this tutorial, we’ll take a look at how to do this with the read command.

The Bash read command is a powerful built-in utility used for word segmentation of strings under Linux.

Since it is a built-in command, as long as we have Bash available there is no need for additional setup steps.

2. Basic Syntax

Let’s explore the basic syntax including all optional parameters:

The options parameters influence how the read command interacts with the input. We will explore these in the upcoming sections.

The name parameter specifies in which variable(s) to store the actual words resulting from the split operation.

2.1. Default Behavior

A no-argument call of read fetches a single line from the standard input stream and assigns it to the REPLY built-in variable:

Let’s now specify some variables to store the results:

If the number of variables is lower than the words obtained, all the remaining words and their delimiters are crammed in the last variable.

By default the read command splits the input into words, considering the <space>,<tab> and <newline> charactersas word delimiters.

We can pass the input on multiple lines using the special <backslash> character:

Let’s take a closer look at this example. We used <backslash> to escape <newline> characters on each line (2 and 3) except for line 4.

The <newline> character also serves as a default input line delimiter. We’ll see a bit later on how to alter this behavior.

2.2. The Internal Field Separator

The Internal Field Separator (IFS) determines what are the word boundaries in a given line. We can modify it to fit our needs and process a custom line:

Notice the second word is empty as two semicolon characters have nothing in between.

Let’s run the same function again but now let’s use <whitespace> as the Internal Field Separator:

Macos Bash Prompt For Input With Default Password

The output changes this time because word splitting behaves differently with <whitespace> characters. A sequence of <whitespace> characters is considered a delimiter.

2.3. Return Codes

The return code is 0 in case of success. If an error happens or an EOF is encountered, the return code is greater than 0:

In this small snippet, we try to pass an invalid variable name and then we print the exit status.

2.4. Adding Basic Options

Let’s take a look at some of the most basic options we can use:

-a array: stores the results of the word split operation in an array rather than separate variables
–e: use the Bash built-in Readline library to read the input line
-s: does not echo the input line to the standard output stream
–p prompt: print the prompt text before requesting the input from the standard input stream without a <newline> character
–i text: print the text as default input on the standard output stream (can only be used in combination with -e)

Let’s now implement a simple password prompt with hidden characters using the -s and -i options:

In some cases, the number of words varies from input to input so we can take advantage of the array-based variable:

The -i option allows us to specify a default input line. Withthe -e option we can also edit the input easily thanks to the Readline built-in library.

3. Advanced Syntax

Now that we’ve seen read in action, let’s take a look at some more advanced options:

-d delim: specify the delimiter of the input line rather than using the <newline> character
–ufd: read the input line from a given file descriptor
–r: treat the <backslash> character as it is (cannot be used for escaping special characters)
-t timeout: attempt to read the input for a given period of seconds
–N: read exactly N characters from the input unless a timeout occurs or EOF is reached

3.1. Reading from Files

Reading from files can be quite useful when we want to process specific fields inside them.

Let’s take a look at some simple structured data for cars:

Now let’s consider extracting specific fields from this CSV file and printing specific fields out:

In this example, we first call the exec built-in bash command to open a file descriptor on our input. Then, we pass this to the read command in a while loop which allows us to read the file line by line.

Finally, we close the file descriptor by calling again the exec command.

Notice that we defined the IFS as part of the while loop. This ensures that further word split operations outside the loop will use the default IFS.

This gives us the following output: Tunerpro definition files mac.

We mentioned in the beginning that we can alter the default input line delimiter.

Let’s consider the case where we structure the input using lines separated by semicolons rather than <newline> characters:

We now modify our function to take into account the new line delimiter:

This provides the same output as before.

3.2. Reading from Other Commands

We can also use the read command in combination with other Linux commands through pipe redirection.

Let’s redirect the output of the ls command and extract the file names and their access rights from the ⁄ (root) folder:

The output varies for each Linux distribution, however, we can see the truncated output as we would expect it:

Let’s drill down a bit more to understand this example. First, we executed the ls -ll / command to print the files in the root directory.

Then, we pipe the output to the standard input of the command group that calls our read.

In this way, we can iteratively process multiple lines of input and print the first and eighth columns of each line.

We also execute read once before the loop to skip the summary that ls prints at the top. This is quite useful when we want to avoid