Why do you use read and while in bash?

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Carole Hand asked a question: Why do you use read and while in bash?
Asked By: Carole Hand
Date created: Tue, Mar 16, 2021 3:16 PM
Date updated: Mon, May 16, 2022 5:02 PM

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Video answer: Shell scripting: while loop and read command

Shell scripting: while loop and read command

Top best answers to the question «Why do you use read and while in bash»

  • Loops using read allow you to iterate through lines of a file that is to be generated or already exists. We have a command or function (lhs) that can generate lines in a file that can be looped through using read and a while loop. We have a file (rhs) with lines that can be looped through using read and a while loop.

FAQ

Those who are looking for an answer to the question «Why do you use read and while in bash?» often ask the following questions:

💻 Do while in bash?

  • The Bash while loop takes the following form: while [CONDITION] do [COMMANDS] done The while statement starts with the while keyword, followed by the conditional expression. The condition is evaluated before executing the commands.

💻 Do while infinite loop bash?

  • To set an infinite while loop use: Use : command to set an infinite loop: #!/bin/bash # Recommend syntax for setting an infinite while loop while : do echo "Do something; hit [CTRL+C] to stop!" done Use the true command to set an infinite loop: #!/bin/bash while true do echo "Do something; hit [CTRL+C] to stop!"

💻 What is read command in bash?

read is a bash built-in command that reads a line from the standard input (or from the file descriptor) and split the line into words. The first word is assigned to the first name, the second one to the second name, and so on… read and echo are enclosed in parentheses and executed in the same subshell.

Video answer: Bash scripting lesson 5 using while loops

Bash scripting lesson 5 using while loops

Your Answer

We've handpicked 28 related questions for you, similar to «Why do you use read and while in bash?» so you can surely find the answer!

How to break a while loop in bash?
  • The break Command. You can use the break command to exit from any loop, like the while and the until loops. #!/bin/bash for number in 10 11 12 13 14 15; do if [ $number -eq 14 ]; then break fi echo "Number: $number" done. The loop runs until it reaches 14 then the command exits the loop. break.
How to increment timeout in bash while loop?
  • Alternatively we can also use ( (timeout=timeout+1)) which can also give us an option to add a custom value for increment. So now the timeout variable will be incremented by 5 in every loop. Let us now take some examples with while loop.
How to print a variable while using bash?
  • Both the echo and the printf commands can be used to print a variable while using Bash. It entirely depends on your personal preference which of these commands you choose to use.
How to skip the while loop in bash?
  • General break statement inside the while loop is as follows: In this example, the break statement will skip the while loop when user enters -1, otherwise it will keep adding two numbers: To resume the next iteration of the enclosing WHILE loop use the continue statement as follows:
Bash script how to read from a file?
  • Create a bash and add the following script which will pass filename from the command line and read the file line by line. The first argument value is read by the variable $1, which will include the filename for reading. If the file is available in the specified location then while loop will read the file line by line and print the file content.

Video answer: Shell scripting tutorial for beginners 17

Shell scripting tutorial for beginners 17 How do i read a file in bash?
  1. #!/bin/bash.
  2. file='read_file.txt'
  3. i=1.
  4. while read line; do.
  5. #Reading each line.
  6. echo "Line No. $ i : $line"
  7. i=$((i+1))
  8. done < $file.
How do i read a filename in bash?
  1. #!/bin/bash.
  2. file=$1.
  3. while read line; do.
  4. #Readind each line in sequence.
  5. echo $line.
  6. done <read_file.txt.

Video answer: How to read a file line by line in bash

How to read a file line by line in bash How do you read a variable in bash?
  1. #!/bin/bash.
  2. # Read the user input.
  3. echo "Enter the user name: "
  4. read first_name.
  5. echo "The Current User Name is $first_name"
  6. echo.
  7. echo "Enter other users'names: "
  8. read name1 name2 name3.
How does the read command in bash work?
  • Let’s break down what will happen when the above code is submitted. cat /etc/passwd will read the contents of the file and pass it as input through the pipe. read command reads each line passed as input from cat command and stores it in the LREAD variable.
How to read a csv file in bash?
  • For Bash versions 4 and above, we can also populate the array using the readarray command: readarray -t array_csv < input.csv This reads lines from input.csv into an array variable: array_csv. The -t option will remove the trailing newlines from each line.

Video answer: Shell scripting tutorial for beginners 15

Shell scripting tutorial for beginners 15 How to read a file in bash shell?
  • Bash Read File. There are many ways that we can use to read a file in Bash Shell Scripting. Some of the important methods are given below (Assuming, name of the file that we are reading is 'read_file.txt'): Reading File Using 'cat fileName' We can use the following syntax to take a print of the contents of the file to a terminal.
How to read a jar file inside bash?
  • Hi All, I am having 7 jar files in a dir. abc like listed below bash-3.00$ cd abc bash-3.00$ ls 123.jar 23wdawd.jar dfsa23.jar dsa.jar wew234.jar adsd234234.jar dfsda423.jarNow i want to assign all this jar files to a variable in the below format ... 4. Shell Programming and Scripting
How to read a word file in bash?
  • Splits on space tab and newline with # the default value of $IFS. If that words contain punctuactions and punctuations are words don't cause much trouble you could try this way. But, as usual, test.txt has been transformed by tr or sed or etc. in "1 word in line" list by tr or sed or etc. and read line by line.
How to read output of a command bash?
  • To get the output of a command in an array, with one line per element, there are essentially 3 ways: With Bash≥4 use mapfile —it's the most efficient: mapfile -t my_array < < (my_command) Otherwise, a loop reading the output (slower, but safe):
How to read the first line in bash?
  • 75 to read first line using bash, use readstatement. eg read -r firstline
How to read user input from bash script?
  • To read the Bash user input, we use the built-in Bash command called read. It takes input from the user and assigns it to the variable. It reads only a single line from the Bash shell. Below is the syntax for its implementation. Follow the given examples to read user input from the Bash Script:
How to read user input in bash script?
  • Read Command - Prompt User for Input in Bash Scripts The Linux read command is a bash builtin that is typically used to accept user input in a shell script. You can assign that input to a variable to be used for processing. There is however, a lot more to the read command.
How to use read builtin in bash shell?
  • The read builtin command takes the following options: Store the words in an indexed array named array. Numbering of array elements starts at zero. Set the delimiter character to delim. This character signals the end of the line. If -d is not used, the default line delimiter is a newline. Get a line of input from an interactive shell.

Video answer: Shell scripting tutorial for beginners 3

Shell scripting tutorial for beginners 3 What should i read in my bash profile?
  • A typical .bash_profile will contain something like: so .bashrc can contain commands to be executed by either login or non-login shells. If you run bash -l rather than just bash, it should read your .bash_profile.
When to use for and while loops in bash?
  • When you use Bash scripting, sometimes it is useful to perform actions using some form of loops. The basic loop commands in Bash scripts are for and while. for loops are typically used when you have a known, finite list, like a series of numbers, a list of items, or counters.
Why does bash work, while / dev / tcp doesn't exist?
  • Why does it work, while /dev/tcp doesn't exists? It's a special file: If host is a valid hostname or Internet address, and port is an integer port number or service name, bash attempts to open a TCP connection to the corresponding socket. Why 5?
Can a bash script read a command line argument?
  • Bash script can read input from command line argument like other programming language. For example, $1 and $2 variable are used to read first and second command line arguments. Create a file named “ command_line.sh ” and add the following script.
Can you read lines in a file using bash?

How to Read a File Line By Line in Bash. The input file ( $input ) is the name of the file you need use by the read command. The read command reads the file line by line, assigning each line to the $line bash shell variable. Once all lines are read from the file the bash while loop will stop.

How do i read a csv file in bash?
  1. Start calc.
  2. Choose File > Open.
  3. Locate the CSV file that you want to open.
  4. If the file has a *. csv extension, select the file.
  5. Click Open.
  6. The Text Import dialog opens.
  7. Specify the options to divide the text in the file into columns.
  8. Click OK.

Video answer: Shell scripting tutorial-39: the 'while' loop

Shell scripting tutorial-39: the 'while' loop